Through Fourier Transform Ioncyclotron Resonance (FTIR) and X-ray Photoelectron Spectroscopy (XPS) characterization of nano fillers before and after modification, it was found that plasma fluorination can graft a large number of fluorinated groups on the surface of SiO2. The introduction of fluorinated SiO2 (FSiO2) can significantly enhance the interfacial bonding strength of the fiber, matrix and filler in GFRP. The DC surface flashover voltage of modified GFRP was further tested. The results show that both SiO2 and FSiO2 can improve the flashover voltage of GFRP. When the concentration of FSiO2 is 3%, the flashover voltage increases most significantly to 14.71 kV, which is 38.77% higher than that of unmodified GFRP. The charge dissipation test results show that the addition of FSiO2 can inhibit the surface charge migration. By the calculation of Density functional theory (DFT) and charge trap, it is found that grafting fluorine-containing groups on SiO2 can increase its band gap and enhance its electron binding ability. Furthermore, a large number of deep trap levels are introduced into the nanointerface inside GFRP to enhance the inhibition of secondary electron collapse, thus increasing the flashover voltage.With the extensive application of glass fiber reinforced polymer (GFRP) in the field of high voltage insulation, its operating environment is becoming more and more complex, and the surface insulation failure has gradually become a pivotal problem affecting the safety of equipment. In this paper, nano-SiO GFRP is a high-performance composite material with high toughness fiber as the skeleton, polymer as the filling matrix. Because of its excellent insulation, mechanical properties, heat resistance and corrosion resistance, it has been widely used in the field of high-voltage transmission. GFRP is not only the key material of composite insulator, composite cross arm, dry reactor and other equipment, but also shows broad application prospects in fully insulated tower and superconducting cable terminals ,2. HowevGFRP will deteriorate and crack under the action of strong electric field during long—term charged operation, and the influence of external environment will cause the material to be affected by moisture, oxidation, pyrolysis and other problems. Finally, the defects such as fiber interface debonding and polymer matrix aging are caused ,6. These2@rubber core-shell structure, which significantly improved the toughness and electrical insulation properties of the composite. Meisak et al. [With the continuous innovation of nano modification technology, the doping of functional nano fillers has become an important means of optimization and upgrading of composite materials ,13. The k et al.  designedk et al.  dispersek et al.  proposed2O as reactive gas, which improved the AC breakdown strength and thermal conductivity of BNNS/EP composites. Xie et al. [x on the surface of GFRP, which improved the shear strength between GFRP layers. This series of studies prove that plasma modification technology has a significant advantage in improving the performance of epoxy composites. At the same time, the use of plasma to achieve the functional modification of nano-filler, then to regulate the nanointerface structure inside the composite material has also aroused great interest of researchers. Plasma fluorination is an important and effective method to modify composite insulating materials. By using the strong electronegativity of fluorine, the trap property inside the material can be regulated, and the surface of the material can be given a very low secondary electron emission coefficient, which significantly improves the surface insulation strength of the composite. Ruan et al. [2O3 by DBD fluoridation and doped it with epoxy resin, increasing the surface flashover voltage of epoxy composite material by 34.7%. Shao et al. [In recent years, plasma technology has been gradually applied to the research on the modification of insulating materials. By bombarding the reactive substance into particles of high energy state, the grafting method is realized on the surface of the material, which has the advantages of high efficiency, low energy consumption and environmental protection. Yan et al.  modifiede et al.  treated e et al.  used lown et al.  modifiedo et al. ,24 graft2 by DBD plasma fluorination and doping it into GFRP. The surface insulation properties of modified GFRP is further investigated, and the influence of nano-particles on the internal interface of GFRP is analyzed by microscopic characterization. In addition, the mechanism of flashover voltage increase is revealed by measuring the surface charge dissipation rate, surface conductivity, trap distribution and DFT calculation of nanoparticles.Considering the advantages of nano-modification and plasma technology, this paper proposes to modify nano-SiO2, 50 nm, purchased from Shanghai Macklin Biochemical Technology Co., Ltd., Shanghai, China. 1H, 1H, 2H, 2H perfluorodecyltrimethoxysilane (fluorinated organic matter) (FAS-17), 97%, produced by Shanghai Macklin Biochemical Technology Co., Ltd., Shanghai China. CF4 and Ar, 99.99% purity, provided by North Special Gas Co., Ltd., Baoding, China.Bisphenol A epoxy resin , methyltetrahydrophthalic anhydride (MTHPA) and 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30) are produced by Shanghai Resin Factory, Shanghai, China. E-class alkalifree glass fber provided by Langfang Anlang Sealing Materials Co., Ltd., Langfang, China. Nano SiO2 under atmospheric pressure, the platform as shown in 2 was pretreated with fluorine-containing organic matter. Appropriate amount of SiO2 filler was placed in a beaker, and a solution containing 2% FAS-17, 3% deionized water and 95% ethanol was added and fully stirred for 30 min. The mass ratio of SiO2 to FAS-17 was 1:0.5. Then it was placed in an incubator at 40 °C for full reaction for 24 h. The pretreated nano- SiO2 was placed in a quartz reactor and the reactor was placed between two round metal electrodes. Then, mixed gas of CF4 and Ar were fed into the reactor, and the flow rate of Ar was controlled by the flowmeter to be 2.5 slm and the flow rate of CF4 to be 0.4 slm. The plasma generator was turned on after the flow was stabilized. The voltage was adjusted to 7 kV and the center frequency was 50 kHz. It could be observed that orange filamentary spark appears in the reactor, and the fluorination treatment time was controlled within 15 min. After plasma fluorination, the filler was calcined in a tubular furnace at high temperature to make the residual FAS-17 fully volatilized. The calcination temperature was 280 °C and the treatment time was 4 h. The calcined powder was fully ground to obtain fluorinated SiO2 (FSiO2), and the fluorination effect was characterized by FTIR and XPS.Filler fluorination: DBD plasma method was used to fluorinate nano-SiO2 before and after fluoride modification was added, and the doping concentration gradient of the filler was controlled to be 1%, 2%, 3%, 4% and 5%. Continue stirring for 30 min after adding the filler to make it evenly dispersed. Then the accelerator DMP-30 was added. The mass ratio of each component is DGEBA:MTHPA:DMP-30 = 100:80:1. The fully mixed material was soaked in glass fiber cloth layer by layer [2 before and after fluorination were labeled as SiO2-GFRP and FSiO2-GFRP respectively, and their cross sections were characterized by SEM.Preparation of composites: First, appropriate amounts of DGEBA and MTHPA were placed in a beaker and heated in a 60 °C oil bath for 30 min to blend well. Then nano- SiOby layer ,27, and The GFRP samples were tested for negative DC flashover along the surface under atmospheric conditions using the uniform pressure rise method . The expIn order to analyze the charge dispersion behavior and trap distribution characteristics on the surface of GFRP materials before and after modification, isothermal surface potential attenuation (ISPD) method was adopted in this paper to measure the surface charge of samples . To ensusI was read through the Gillespie 6517 B electrometer, and the surface resistivity of the material could be calculated according to the following formula.d is the distance between the inner electrode and the protection electrode, D1 is the diameter of the inner electrode, D2 is the inner diameter of the protection electrode, and U is the test voltage. Each sample was tested 10 times. The sample was depolarized for 30 s before each measurement, and then the average value was calculated as the surface resistivity of the sampleIn the study of surface flashover of epoxy composite insulation materials, the surface resistivity of the material is also a crutial parameter that affects its surface insulation strength. In this paper, the three-electrode method was adopted to measure the surface resistivity of the sample . During 2 before and after fluoridation are shown in −1 for SiO2 before and after fluorination. In addition, symmetrical stretching vibration peaks of Si-O-Si groups appear near 800 cm−1 and 475 cm−1 [2 filler has an asymmetric stretching peak at 1152.7 cm−1 that can be attributed to -CF2 [2 active groups in the ionized product of CF4 and FAS-17, which are grafted on the surface of the filler by adsorption or direct bonding. In addition, there is a stretching vibration peak that can be attributed to C-F bond near 1216 cm−1 [x groups are grafted on the surface of the nano filler, the strong binding effect of fluorine on electrons will reduce the surface polarizability of the filler, which is conducive to improving the insulation performance of the material. The above characterization results showed that the -CFx group was successfully grafted on the filler surface during the plasma fluorination process. It can be seen from the full spectrum of XPS that FSiO2 has a strong F 1 s peak at 689 eV compared with unfluorinated SiO2. In order to explore the existing form of fluorinated groups on the surface of SiO2, we have carried out peak-splitting treatment for element C, as shown in 3, -CF2, C-F and C-O peaks, which appear around 293.2 eV, 291.0 eV, 287.9 eV and 285.4 eV respectively, and the intensity relationship is -CF2 > C-O > -CF3 > C-F. It can be seen that CF4 and part of FAS-17 as fluorine sources are ionized step by step in the plasma discharge process, mainly to CF22+ and CF3+, and combined with the active groups on the surface of nano SiO2, in the form of -CFx grafted on the surface of filler.The FTIR spectroscopy and XPS test results of SiO475 cm−1 ,30. Whil to -CF2 . The ele216 cm−1 . C-F is 2 before and after fluoridation is shown in 2 reaches 40.66%, while the proportion of Si element and O element decreases about 20% compared with SiO2. It can be seen that fluorine-containing groups can be grafted onto the surface of nanoparticles well after being infiltrated by FAS-17 and treated by plasma fluorination. This makes the original polar groups such as hydroxyl group covered on the surface of the filler, or bombarded in the process of plasma discharge, resulting in fracture. The introduction of fluorine-containing groups can reduce the surface energy of the nano-filler and inhibit the agglomeration effect of the filler in the process of composite synthesis. At the same time, fluorine-containing groups introduced by plasma fluorination can bond with epoxy resin matrix to form fluorine-containing nanointerface, which can better regulate the degree of interfacial binding between epoxy resin, glass fiber and nano-SiO2, and introduce charge traps with higher energy levels at the interface.The content ratio of main elements of SiO2 and FSiO2 on fiber interface were analyzed. It can be seen from 2 can fill the pores between fiber and resin matrix to a certain extent, and the existence of active groups such as hydroxyl and carboxyl groups of silica can also enhance the degree of binding between epoxy matrix and glass fiber. However, as can be seen from 2 filler will have agglomeration effect, which also becomes the reason restricting the further optimization of the microstructure of GFRP materials. Therefore, there are still pores in the modified GFRP. As can be seen from 2 can make the binding between the epoxy resin and glass fiber compactness. There are no obvious pores in FSiO2-GFRP, which reduces the interface defects between epoxy matrix and glass fiber. According to the characterization results in 2 shows good dispersion in GFRP, its agglomeration effect is significantly weakened, and the particle size of the aggregates is also much smaller than that of the unmodified system. The analysis shows that the etching roughness of FSiO2 surface treated by plasma fluorination will be significantly improved, which makes it form a mechanical action of occluding with fiber and matrix, and enhances the interface bonding strength. At the same time, the fluorine-containing groups on the surface of FSiO2 can also act as adhesives, which effectively improves the bonding degree between nano filler, glass fiber and epoxy resin.The cross sections of GFRP materials of different systems were characterized, and the effects of SiO2-GFRP and FSiO2-GFRP is higher than that of unmodified GFRP, and shows a trend of “first rising and then decreasing” with the increase of filler concentration. When the filler concentration of SiO2-GFRP was 2%, the flashover voltage was 12.59 kV, 18.77% higher than that of GFRP, and then the flashover voltage began to decrease. For FSiO2-GFRP, when the packing concentration is 3%, the maximum flashover voltage is 14.71 kV, which is 38.77% higher than that of GFRP, and the subsequent flashover voltage improvement effect is not obvious.The surface flashover voltage of modified GFRP with different formulations was tested 50 times in atmospheric environment. After eliminating the bad points through the boxplot, the trend diagram of flashover voltage changing with different packing concentrations was made, as shown in 2-GFRP and FSiO2-GFRP, it can be found that the flashover voltage improvement effect of the fluorinated material is more obvious. At the same time, it can be seen that the concentration of the optimal modification value of FSiO2-GFRP lags behind that of SiO2-GFRP. We believe that the introduction of fluorine-containing groups regulates the internal interface of GFRP, which further improves the insulation strength of the materials. When the filling concentration of unmodified nano-SiO2 increases gradually, the agglomeration will be serious, which will lead to the modification limited or even reduced. While the fluorination of SiO2 improves the dispersion of nanoparticles, so the range of its action concentration is also widened.By comparing SiO2-GFRP and FSiO2-GFRP with different concentrations. As can be seen from the figure, doping nano-SiO2 into GFRP can accelerate the surface charge dissipation rate of the composite. When the packing concentration is 2%, the dissipation rate increases the highest, and the final potential decreases about 36% compared with the initial potential. When the concentration of SiO2 increases further, the surface charge dissipation rate of GFRP becomes stable. After the fluorination of SiO2, the charge dissipation rate of FSiO2-GFRP is lower than that of GFRP. The charge dissipation ratio is about 2~7%, the higher the packing concentration, the slower the charge dissipation. This is because a large number of deep traps are formed inside modified GFRP by the introduction of fluorine containing groups. When charges migrate on the surface of the material under the action of external electric field, charges will be captured by the trap of high energy level and it is difficult to escape, thus suppressing the carrier migration rate on the surface of the material.2 model with a diameter of 7 Å was intercepted from the structure of the amorphous SiO2 model by using Materials Studio software, which contains 147 atoms. This is enough to reflect the nature of the material itself and meet the requirements of calculation. Combined with the characterization results of FTIR and XPS, part of the H atoms on its surface were replaced with -CF2 and -CF3 fluorinated groups to simulate the FSiO2, as shown in The trap energy distribution of composites is closely related to the properties of filler and nanointerface. Ding and Du et al. ,34 propoDuring the calculation, the quality is set to fine, and the maximum number of iterative steps and cycles is 1000. In order to speed up the convergence, the smudge method is used, with a value of 0.005.2 and FSiO2, it can be seen that the energy of SiO2 and FSiO2 is mainly distributed in the range of −20~10 eV and reaches the maximum peak value at −18 eV and −5 eV, respectively. The bandgap width of SiO2 is about 4.986 eV, while that of FSiO2 is about 5.250 eV. The gap width, also known as the band gap, can reflect the transition ability of electrons. In the study of insulating materials, gapE is considered as a form of trap. The results show that the fluorinated grafting of SiO2 can increase the band gap width and make valence band electrons more difficult to transition into conduction band electrons, which is equivalent to introducing high level deep charge trap into the material and improving the insulation performance of FSiO2-GFRP.U and dissipation time t. Matlab software was used for curve fitting of surface potential and dissipation time, and the expression was:a, b, x, and y represent the density peaks of different trap energy levels. By solving the fitted curve through Equations (3) and (4), the relationship between trap energy level D and trap density I can be obtained:T is the ambient temperature during the test, Unit K; Bk is Boltzmann constant; ATEν is the electron escape rate, and the calculation formula is as follows:Based on ISPD method, the surface trap distribution characteristics of GFRP with different systems were calculated . By proc2-GFRP and FSiO2-GFRP with different concentrations, the corresponding surface trap distribution is calculated, as shown in 2 and FSiO2 affect the charge dissipation behavior of the composites mainly by changing the trap energy level of GFRP. For SiO2-GFRP, when the packing concentration is higher than 2%, the shallow trap density increases obviously, and the deep trap energy level also decreases to a certain extent, which is the main reason for the acceleration of the surface charge dissipation rate. When the filling concentration is 1%, the introduction of a small amount of nano-filler will affect the crosslinking structure of the original epoxy resin. This will lead to the destruction of the original charge transmission channel, so the acceleration effect of nano SiO2 on charge is difficult to reflect. When the packing concentration increases, a large number of nanointerfaces formed inside GFRP bring more shallow trap levels, so the carrier migration ability is enhanced. The trap energy level of FSiO2-GFRP shows an obvious upward trend with the increase of filler concentration. This indicates that the ability of trapping and binding charge on the surface of FSiO2-GFRP material is enhanced, which is basically consistent with the dissipation of charge. The analysis shows that the grafted fluorine-containing groups on the surface of FSiO2 form a large number of fluorine-containing interface regions in GFRP. And the strong electron binding ability of fluorine makes it easy to capture charges, while the captured charges are difficult to be excited again. At the same time, the charge center formed by the captured carriers also has strong binding ability, which is reflected in the enhancement of trap energy level on the surface of FSiO2-GFRP.According to the measured surface potential of SiO2, it is found that grafting fluorine on the surface of SiO2 can increase its band gap and enhance its electron binding ability, which is consistent with the above analysis. It is also observed that when the filling concentration of FSiO2 increases to 5%, the trap energy level decreases. This is because the filling limit of nano-filler in epoxy resin is basically about 5%, and excessive doping leads to agglomeration and stacking of filler, thus forming more physical defects, namely shallow traps. Therefore, the binding ability of the composite to the surface charge is slightly weakened, and the ability to inhibit the occurrence of flashover along the surface is weakened, and the flashover voltage begins to drop.Combined with the calculation results of the state density of SiO2 before and after fluorination on GFRP flashover voltage, the surface resistivity of GFRP was tested, and the results are shown in 2-GFRP shows an inverted “N” type change trend with the increase of filler concentration, while the surface resistivity of FSiO2-GFRP shows a trend of “first increasing then decreasing”. When the concentration of SiO2 is 1%, the resistivity of GFRP is relatively high, about 19 × 1015 Ω·cm, which is consistent with the analysis conclusion of the above trap. With the further increase of packing concentration, the surface resistivity of GFRP decreases significantly, which is related to the introduction of active groups and interface regions. With the further increase of filler concentration, the insulating property of nano-SiO2 itself began to play a role, so the resistivity rose to a certain extent. However, when the packing concentration continues to increase, the agglomeration and packing stacking effect enhance the carrier transport ability, so that the surface resistivity of GFRP increases slightly. When using FSiO2 as filler, the surface resistivity of FSiO2-GFRP is higher than that of SiO2-GFRP. When the concentration of FSiO2 increases to 3%, the resistivity of FSiO2-GFRP increases to about 23 × 1015 Ω·cm, which is mainly dependent on the introduction of a large number of fluorine-containing nanointerfaces in the material. This effect is highly consistent with the above analysis. With the further increase of filler concentration, F-SiO2 also appeared agglomeration phenomenon, resulting in a slight decrease in surface resistivity, the surface resistivity is about 9 × 1015 Ω·cm when the concentration is 5%.In order to further analyze the influence of nano-SiOAccording to literature , the cha2-GFRP, nano-filler and fiber form a network conducive to charge dissipation inside the composite. At the same time, the deep traps introduced by the nano-interface are low in energy level, and more shallow traps are introduced. The trapped charges are easier to detrap, and it is not easy to restrain the occurrence of surface discharge by binding the charges. In addition, the surface resistivity of the composite is low, which is conducive to the surface charge migration, avoiding a large amount of charge accumulation on the surface in a short time, and increasing flashover voltage to a certain extent. The flashover voltage increase of FSiO2-GFRP is more significant. The analysis shows that after plasma fluorination, FSiO2 promotes the bonding strength between nano particles, fibers and resin matrix, which optimizes the microstructure of the material and improves the comprehensive property. On the other hand, the grafted fluorine-containing groups on the surface of FSiO2 increase the band gap and deepen the trap energy level on the surface. The energy required for charge detrapping increases, which inhibits the secondary electron emission and electron avalanche process in the development of flashover. Therefore, the DC flashover voltage along the surface of the material is significantly increased.For SiO2, and the filler was modified by DBD plasma fluorination. The influence of nano- SiO2 before and after fluorination on the surface insulation performance of GFRP was further studied. The results show that fluorine is mainly grafted on the surface of nano-SiO2 in the form of -CFx. After plasma fluorination, FSiO2 can enhance the binding degree of epoxy resin matrix and glass fiber, which is conducive to improve the comprehensive performance of GFRP materials. The DC flashover voltage of GFRP can be improved by nano-SiO2 before and after modification. Among them, the flashover voltage of GFRP modified by FSiO2 doping increases more significantly. When the filling concentration of FSiO2 is 3%, the flashover voltage of GFRP reaches 14.71 kV, which is 38.77% higher than that of unmodified GFRP. The surface charge dissipation rate of GFRP samples was tested. It was found that SiO2 can accelerate the charge dissipation rate of GFRP surface, while FSiO2 can inhibit the charge dissipation of the material surface. By calculating the state density of nano-SiO2 and the trap distribution of composites before and after modification, it is found that grafting fluorine on SiO2 surface can increase its band gap and enhance its electron binding ability. This is equivalent to increasing the energy level of deep trap inside GFRP, improving the ability to inhibit secondary electron emission during the development of flashover discharge, and thus increasing the surface flashover voltage of GFRP. The research in this paper provides a new idea for improving the surface insulation performance of GFRP in the field of high voltage insulation, expands the application prospect of high performance GFRP, and promotes the application of plasma technology in the modification of composite insulation materials.In this paper, FAS-17 was used to pretreat nano-SiO


In this paper, rice husk ash (RHA) with different average pore diameters and specific surface areas was used to replace 10% slag in the preparation of alkali-activated slag (AAS) pastes. The effect of RHA addition on the shrinkage, hydration, and strength of AAS pastes was studied. The results show that RHA with a porous structure will pre-absorb part of the mixing water during paste preparation, resulting in a decrease in the fluidity of AAS pastes by 5–20 mm. RHA has a significant inhibitory effect on the shrinkage of AAS pastes. The autogenous shrinkage of AAS pastes decreases by 18–55% at 7 days, and the drying shrinkage decreases by 7–18% at 28 days. This shrinkage reduction effect weakens with the decrease in RHA particle size. RHA has no obvious effect on the type of hydration products of AAS pastes, whereas RHA after proper grinding treatment can significantly improve the hydration degree. Therefore, more hydration products are generated and fills the internal pores of the pastes, which significantly improves the mechanical properties of the AAS pastes. The 28 day compressive strength of sample R10M30  is 13 MPa higher than that of blank sample. Therefore, the cumulative hydration heat is higher than Ref. However, due to internal porous structure of RHA, it can absorb part of the pore solution [From solution . TherefoThe XRD patterns of AAS products cured for 28 days are demonstrated in The pore structures of samples are analyzed cured for 7 days a,b and 229Si MAS NMR spectra of mixture of slag and RHA, slag and SF, and AAS pastes cured for 28 days are shown in 1-a and Q1-b peaks are at around −77.1 ppm and −78.7 ppm, which mainly represent chain-end Si-O tetrahedron without specifically assigning each to a particular chemical environment. The Q2(1Al) peak is at −88.5 ppm, which mainly represents a middle-chain Si-O tetrahedron in which an adjacent Si in C-(A) -S-H gels is replaced by an Al [2-b and Q2-p mainly represent the middle-chain Si-O tetrahedron, located at −84.2 ppm and −86.8 ppm, respectively [4-a) and −111 ppm (Q4-b), respectively [4-a peak in hydration products of RHA disappeared, whereas the peak intensity of Q4-b in hydration products of SF10 decreases. The reason is that the active silicon in RHA and SF is consumed by the hydration reaction.The by an Al . Q2-b anectively . As showectively ,48. This2(1Al) peak and Rs increase gradually. The Rs of R10M0 is 5.28% lower than Ref. The Rs of R10M15 and R10M30 are 69.31% and 69.97%, respectively. The difference between them is only 0.66%. The reason is that the activity of RHA can be significantly increased by proper milling, whereas the activity of RHA can be decreased by excessive milling, and even the activity of pozzolanic ash may even become lower. Compared with the SF10, the Rs of R10M15 and R10M30 are higher. The reason is that not only due to the effect of mechanical activation on RHA, but also related to the internal curing effect of its internal porous structure. Therefore, RHA after proper grinding is better than SF in promoting hydration reaction, being consistent with the results of isothermal calorimetry.In addition, integrated intensities of Si-O tetrahedron can reflect the degree of hydration (Rs) of the slag, and can be obtained according to the corresponding calculation formula , the cal1H low field NMR technique was applied, so as to further explore the effect of RHA on the shrinkage mitigation mechanisms. The effects of RHA on T2 relaxation time distribution and signal intensity changes in free water inside AAS samples  the internal specific surface area of raw ash is small, which leads to the reduction of the pozzolanic activity, the intensity of hydration reaction and the consumption of internal free water. (ⅱ) RHA has internal curing effect . The incCompared with the Ref, the drying shrinkage value of SF10 was slightly reduced by only 1.6%. The phenomenon can be ascribed to two reasons: (ⅰ) dilution effect. The addition of SF will cause dilution effect to the reaction system , and theAdditionally, the drying shrinkage of R10M0 decreases most obviously. The drying shrinkage of the AAS pastes is mainly provided by the autogenous shrinkage in the first 7 d, and the 7 d–28 d is mainly related to the volatilization of the internal water into the dry environment. Therefore, the reason why the raw ash reduces the drying shrinkage of the sample most obviously is precisely because it has a great alleviating and inhibiting effect on the early autogenous shrinkage of the sample, which is closely related to the mitigating effect, low pozzolanic activity and internal curing effect. The pozzolanic activity of RHA increased gradually with the decrease of particle size. The effect of alleviating the early autogenous shrinkage of the sample becomes poor. As a result, the drying shrinkage values of R10M15 and R10M30 samples are larger than R10M0. This is consistent with the autogenous shrinkage result.The compressive strength of the Ref is 94 MPa at 3 days, while the compressive strength of SF10 is always slightly higher (1–3 MPa) than Ref and R10M0 is lower than Ref in 29Si MAS NMR and pore structure analyses also show that the hydration degree of R10M15 and R10M30 is higher than that of Ref, whereas the total porosity is the opposite. The reason is that the pozzolanic activity of RHA increases with the decrease of specific surface area, which greatly promotes the internal hydration reaction of the samples. Thus, the cumulative heat release of hydration and the total hydration degree increases. At the same time, the pores inside the samples are also filled with more hydration products, therefore the pore structure inside the matrix is relatively compact. However, the RHA pozzolanic activity of R10M0 is still low and the cumulative heat release decrease due to the reduction of slag content in the reaction system. Therefore, the internal hydration degree is also lower than Ref, and the pores in the matrix cannot be filled with hydration products, therefore, the total porosity is higher than Ref significantly. In addition, the increase of hydration product content in R10M15 is higher than R10M30. The reason is that the excessive grinding will destroy the porous structure inside RHA, and the inner curing effect will degrade. The result confirms that with proper milling treatment, RHA can not only play the role of internal curing agent, so that its shrinkage performance has been improved, but also promote the internal hydration and optimize the internal pore structure, thus improving the mechanical properties. However, the compressive strength of AAS pastes is greatly affected by the specific surface area of RHA. The compressive strength of R10M15 and R10M0 at a later hydration stage was lower than that of blank group. This is due to the low pozzolanic activity of RHA with larger particle size. Meanwhile, some of the water stored in the pores of the porous structure of RHA is not fully released.The addition of RHA will delay the exothermic peak of hydration. The reason is that RHA will absorb some of the pore solution in the AAS pastes and reduce the hydration reaction rate. With the progress of hydration reaction, the cumulative hydration heat of R10M15 and R10M30 is higher than that of Ref. In addition, solid state 1H NMR. With the decrease of the average pore diameter of RHA, the pozzolanic activity of RHA increases, which can promote the hydration reaction inside the samples. However, the internal pore structure of RHA is destroyed by milling, and its effect on alleviating the relative humidity reduction is weakened. As a result, the autogenous shrinkage of R10M30 and R10M15 samples is increased, but still lower than SF10 and Ref samples.The incorporation of RHA in R10M15 and R10M30 promotes the development of chemical shrinkage of AAS pastes at 14 days. The reason is that the particle size of rice husk ash becomes smaller after grinding, and the specific surface area increases, which is more conducive to providing active silicon for the hydration reaction, which is consistent with the NMR. At the same time, its internal porous structure can also absorb part of the pore solution and further increases the hydration degree in the later age of hydration. This promotion is even stronger than SF. RHA can also alleviate the early autogenous shrinkage of AAS pastes, and the alleviating effect of raw ash is the most significant. The reason is that the pozzolanic activity of raw ash is poor, and it has little effect on the hydration reaction. And just like the incorporation of SF, there is a dilution effect on the whole reaction system due to the reduction of slag content. Another reason might be that the pore structure inside the raw ash is relatively intact and has a good curing effect, which can alleviate the reduction of the relative humidity inside the samples, being consistent with the results of After the hydration of 28 days, RHA can reduce the drying shrinkage significantly. The reason is that RHA can inhibit the autogenous shrinkage of AAS pastes. Another reason might be that RHA can promote the hydration of AAS pastes, and generate more hydration products to fill the pores inside the matrix, which can reduce the degree of water loss of AAS pastes in dry environment, so that the drying shrinkage of AAS pastes is reduced by about 5–10% compared with SF10. The result confirms that after proper milling treatment, RHA will perform high pozzolanic activity and internal curing effect, which is stronger than SF10 in promoting hydration and reducing shrinkage of AAS pastes.The incorporation of RHA will cause the fluidity loss of AAS pastes, and the loss degree decreases with the decrease of RHA average pore diameter. Fluidity loss is induced by water uptake of internal pores. In addition, RHA can prolong the setting time of AAS pastes, and the setting time is shortened with the decrease of the average pore diameter;RHA retards the arrival time of hydration reaction peak of AAS pastes, while this retarding effect is mitigated with the decreased average pore diameter of RHA. However, RHA increases the cumulative hydration heat of AAS pastes. In addition, the hydration degree of AAS pastes is also promoted by adding RHA;The incorporation of RHA increases the chemical shrinkage of AAS pastes. However, RHA can alleviate autogenous shrinkage at 7 days and drying shrinkage at 28 days of AAS pastes. The alleviating effect deteriorated with the decrease of the average pore diameter of RHA;The incorporation of RHA coarsens the early pore structure of AAS pastes and increased the total porosity of samples. However, with the progress of hydration reaction, the internal pore structure is refined at later age, and the total porosity decreases;The incorporation of RHA can significantly enhance the compressive strength of AAS pastes at later age. For example, by adding 10% RHA with a D50 of 8.3 μm, the compressive strength of AAS pastes can reach 155 MPa at 28 days, increasing by 13 MPa compared with that of AAS pastes without RHA.In this paper, the shrinkage-mitigating mechanism of RHA and hydration kinetics of AAS pastes containing RHA was studied, as well as the strength development. Based on the research above, the main conclusions can be drawn as follows:


Fires not only cause air pollution, but also disrupt ecosystems. Knowledge of the flammability parameters and proper flame-retardant modification of materials hinders the origin and spread of a fire, while also protecting against air pollution. The aim of this study was to obtain fire-retardant modifications of the epoxy resin, and then to analyse the effect of the introduced additives on the rate of heat release, the thermokinetic properties and the toxicity of volatile combustible products. The modifiers of the epoxy resin were organophosphorus compounds and aluminium and magnesium hydroxides, with a grain size of 10 nm. The introduced additives were found to be effective flame retardants as they reduced the rate of heat release and the amounts of toxic products of thermal decomposition and combustion. The HRR Negative environmental impacts of fires range from adverse to inappropriate, depending on their extent. These impacts can be divided into three categories: immediate (fire brigade intervention), long-term (months and years after the fire) and inapplicable. The initial assessment considers the atmosphere and corresponds to a classification of the severity of the impacts based on the different phases of the fire. Polymeric materials such as cured epoxy resins are often found in construction, transport, electronics and electrical engineering, medicine and households. Very good mechanical resistance, high chemical resistance, moisture resistance, ease of processing and colouring makes them suitable for a wide range of applications ,2,3,4. UTo date, halogen compounds have been effective and popular flame retardants for epoxies. Regrettably, their use is limited or banned due to the toxic effects of thermal decomposition and combustion products on humans and the environment, because of the release of large quantities of irritant and toxic gaseous substances during combustion, including bromine, hydrogen chloride, dibenzodioxins and dibenzofurans ,6. TheseCurrently, one of the most effective methods of fire-retardant modification of polymers is the introduction of nano-additives to the polymer matrix . The nanThus far, there is no extensive analysis of the flammable, smoke-generating and toxicity properties of this resin selected for testing—Epidian 5, with the applied additives and mixed modifications. Therefore, the main aim of this work was to solve the flammability problem of epoxy resin by obtaining an effective series of fire-retardant modifications of this material, and then to perform a comprehensive flammability analysis, including the explanation of the mechanism of action of the fire retardants used.The subject of this study was the preparation of a series of cross-linked, modified epoxy resin materials, and the subsequent analysis of their thermal decomposition products in the combustion process.The polymer base was an epoxy resin from the “Organika-Sarzyna” Chemical Plant in Nowa Sarzyna called Epidian 5 . It has a broad range of applications, e.g., in construction, electronics, as well as in everyday life. Among other things, it is used in the production of flooring compounds, concrete primers and as a component of adhesives and varnishes. Additionally, it serves as a binder for epoxy-glass laminates and in electronics for flooding electrical and electronic components. It is a viscous liquid characterised, among others, by minimal shrinkage while curing, the possibility of curing at room temperature and good adhesion to most materials, such as metals, glass, ceramics and wood. Additional features include good mechanical properties and resistance to a wide range of chemical agents, such as oils, greases, diluted lyes and acids, resistance to short-term exposure to temperatures up to 80 °C and excellent dielectric properties . Conside2 99% and Al(OH)3 99.9%, whose distributor was Alchem Grupa Sp. z o.o. The grading of the hydroxides used was 10 nm. To cure the mixture, use was made of the hardener Z-1 TECZA (triethylenetetramine), with the chemical formula C6H18N4.Halogen-free mixtures were used, such as organophosphorus ones, i.e., Roflam B7 and Roflam F5 (description below), and nano-additives serving as nanofillers, Mg(OH)Roflam F5—A phosphoric flame retardant, phenyl-isopropyl-phenyl phosphate, which provides a high flame retardancy profile to plastics. During the combustion process, the product acts in the solid phase, forming a charred layer on the surface of the plastic, inhibiting the spread of the flame. Roflam F5 is a halogen-free flame retardant, and therefore, no toxic gases are released during combustion in the gas phase, such as HCl or HBr .Roflam B7—A tert-butylphenyl phosphate, a halogen-free phosphoric flame retardant in the form of a colourless liquid with low dynamic viscosity. Considering its very good compatibility with many liquid raw materials, it is successfully used in polyurethane plastics, epoxy resins, vinyl ester resins and unsaturated polyester resins. It is a fire-protection agent that belongs to the group of phosphorus aryl esters . Accordi2 or Al(OH)3 in the range of 5–10% by weight, were introduced to the epoxy base—Epidian 5—in appropriate amounts, while simultaneously stirring on a mechanical stirrer at a speed of V = 300 rpm. Once all the ingredients had been added, stirring continued for a further 20 min, after which the entire mixture was placed in an ultrasonic bath for 1 h with continuous stirring on a stirrer. In the next step, the uncured mixture was degassed using a mechanical pump. The unmodified, as well as the modified epoxy resin, was cured in a further step with the addition of the hardener Z-1 at a rate of 12 to 100 parts by weight of resin and poured into the moulded parts. The curing process was carried out at room temperature, and the gelation time was approximately 15 min. Initial curing was achieved after about 3 h, with a cure rate of about 80–90% after 24 h, so the samples were then post-cured by placing in an oven for a further 2 h at 120 °C. The composition and determination of the samples produced are shown in The flame-retardant modifications analysed for the materials formed from Epidian 5 were obtained by adding the individual flame-retardant components in the appropriate concentrations. The halogen-free admixtures Roflam B7 or Roflam F5 in the range of 5–10% by weight, as well as the nanofillers Mg(OH)2. The applied thermal radiation power simulated phase I of the fire according to the standard curve “fire temperature–combustion time”.The fire characteristics of the analysed epoxy resin modifications were carried out using the cone calorimeter method in accordance with the standard . With thA thermal analysis of both unmodified and modified epoxy resin was performed by the dynamic technique according to . On the 2, the concentrations of CO2 and CO using an FTIR analyser at a combustion time of 600 s were recorded. A schematic of the station is shown in In accordance with the standard  at a theSelected fire parameters of the resulting epoxy modifications are summarised in 2 of the epoxy materials tested are shown in 2 increased the time to ignition of the sample to 38 s.The heat release rate curves at a thermal exposure of 50 kW/mmax and HRRav values of all epoxy resin modifications of Epidian 5 . The highest values of HRRmax of 1318 kW/m2 and HRRav of 603 kW/m2 were recorded for Epidian 5. The single-component modification of 5 wt.% Al(OH)3 was the most effective at lowering HRRmax, to 748 kW/m2, among the tested resins as a result of water vapour release and the formation of a glassy film during the combustion process, protecting the material from heat and oxygen access. In turn, HRRav was reduced to a value equal to 310 kW/m2 after the introduction of 10 wt.% of Roflam B7 and 5 wt.% of Al(OH)3. When only one component was used for the modification, the lowest HRRav value of 364 kW/m2 was obtained after the introduction of 5 wt.% Mg(OH)2. A decrease in SEAav (mean specific extinction coefficient) was observed for all analysed modifications. The lowest value of 158 m2/kg (81% lower than Ep5) was recorded for the sample 5M. In contrast, the simultaneous introduction of 5 wt.% Roflam F5 and 10 wt.% Al(OH)3 caused the opposite effect and an increase in this parameter. It can be concluded that Roflam F5 accelerated the decomposition of the polymer by forming decomposition products together with aluminium hydroxide, increasing the light attenuation surface area of the smoke particles. After analysing the wt.% of sample residue after combustion, it can be concluded that the effect of the phosphorus-based flame-retardant additives in the combustion of Epidian 5 is mainly related to the gas phase. In the analysed thermal exposure, the introduction of Roflam B7 with aluminium or magnesium hydroxide into the epoxy matrix increased the time to ignition of the sample and the time to reach HRRmax for sample 5F + 10A by 20 s and 58 s, respectively. The amount of CO released from 1 kg of modified Epidian 5 material was typically at an average level of 2.3 kg/kg compared to unmodified cured Epidian 5. In contrast, when only hydroxides were used for modification, the amount of CO per 1 kg of material decreased. The amount of CO2 released per 1 kg of material, in the case of the 5F + 10A sample, was the lowest, at 10.0 kg/kg (12% lower compared to Ep5). The mechanism of action of the mixed flame retardants was through a synergistic effect. Phosphorus compounds acted as radical scavengers in the gas phase, scavenging free radicals at elevated temperatures in the combustion process, while inorganic compounds, i.e., Mg(OH)2 or Al(OH)3, caused the release of water vapour, effectively lowering the value of HRRmax.All the introduced flame retardants were effective at lowering the HRROn the basis of the TG and DTG thermogravimetric curves, the values of selected parameters describing the thermal decomposition process of the epoxy materials tested were obtained, which are summarised in 2 (sample 5M) or 5 wt.% organophosphorus compounds and 10 wt.% magnesium hydroxide (samples 5B + 10M and 5F + 10M) were higher compared to cured Epidian 5 . The temperatures of the maximum sample weight loss rate in phase I of the transformation were highest for the 5M sample. The difference in values between Ep5 and 5M was 22 °C.Data presented in 2, as the half-life was most effectively lowered compared to the unmodified sample.Analysing the epoxy modifications, it can be seen that a synergistic effect was achieved by the addition of 5 wt.% to the epoxy resin Roflam F5 and 5 wt.% Mg(OH)2. 3. 2, as a function of time in the process of combustion of flame-retardant epoxy resin modifications.All analysed samples were found to release CO and CO2 concentration, the time to reach this value was different for each modification. For example, sample 5F obtained the highest value of 35,389 ppm at the end of the analysis time. In contrast, the shortest time of 275 s was characteristic of the 10F + 5M sample, which at the same time had the highest CO value during analysis. For the cured unmodified epoxy resin, the highest CO2 concentration value of 47,271 ppm was recorded in the analysed volume of the test chamber.On the basis of the maximum values obtained for the concentration of the toxic gases emitted, it is clear that for all the samples analysed, the maximum value of the CO concentration was obtained at 600 s, the final time of analysis. The lowest CO value was recorded for sample 5M—at 1721 ppm. In the case of CO2 volumetric concentration during the analysis, the exact time at which the increase in the CO2 concentration occurred can be observed, which was also the time at which combustion of the sample began. In the initial phase, the increase in the CO2 concentration for most of the samples analysed was almost identical, with the exception of 5M + 10B and the unmodified Epidian 5 sample. In the case of the 10F + 5M sample, by 275 s, the CO2 concentration of this sample had risen to a value of 34,783 ppm, and then it gradually decreased, reaching its lowest value of 467 ppm at 600 s. The CO2 concentration of the Epidian 5 sample continued to increase for most of the measured time, reaching the highest value of all the samples analysed, equal to 47,271 ppm at 405 s, and then it decreased to a value equal to 43,614 ppm at 600 s. The CO2 volumetric concentration values of the other samples analysed up to 600 s ranged from 6346 to 35,367 ppm.From 3 at a combustion time of 600 s, the maximum concentration of CO2 released from the samples of fire-modified Epidian 5 was lower than the corresponding maximum concentration for Epidian 5. This difference—depending on the additive used—ranged from 56,447 to 23,240 ppm.Taking On the basis of the study, it can be concluded that the introduction of flame-retardant additives consisting of aluminium hydroxide, magnesium hydroxide and organophosphorus compounds into the Epidian 5 epoxy resin reduced its flammability and ignitability, as well as the toxicity of thermal decomposition and combustion products. Increasing the concentration of hydroxides and organophosphorus compounds in the epoxy material tested improved the fire safety. This finding was confirmed by, among other things, a reduction in the maximum rate of heat released from the burning epoxy modification (by 9–59%), which translates into a reduction in the power of the actual fire in which they were burned, similar to that reported in the literature ,38,39,40On the basis of the analysed modifications of the epoxy resin, it is possible to confirm the inhibitory effect of the applied flame retardants: magnesium hydroxide, aluminium hydroxide, Roflam B7 and Roflam F5, and their mixtures.max) and the average value of the heat release rate (HRRav) of the modification of Epidian 5 through the introduction of single flame retardants as well as the flame-retardant system were found to be lower than the values of the same parameters for the cured unmodified epoxy material. This demonstrates that the flame retardants used are effective combustion modifiers for epoxy materials obtained on the basis of Epidian 5. The most effective modification of Epidian 5, taking into account the average and maximum heat release rates, was the introduction of 5 wt.% Mg(OH)2 in the case of single-component additives or, for mixed compositions, 10 wt.% Roflam F5 and 5 wt.% Al(OH)3.The maximum value of the heat release rate  hydroxide or magnesium (II) hydroxide) resulted in the evolution of water vapor, which effectively reduced the HRRlication .3 showed a higher susceptibility to form a charred layer on the surface of the epoxy resin compared to the cured unmodified epoxy resin and the other two-component modifications. Flame retardants containing a phosphorus atom or atoms in the particular polymer arrangements usually belong to the ecological anti-pyrenes [The onset temperature of thermal decomposition of compositions mixed simultaneously with hydroxides and organophosphorus compounds is for the most part lower than that of compositions modified with hydroxides alone or with Epidian 5. The simultaneous introduction of 5 wt.% Roflam F5 and 10 wt.% magnesium hydroxide into the epoxy resin most effectively increased the onset temperature of thermal decomposition of phase I (this temperature is 340 °C). The opposite results were obtained when 10 wt.% was used for the modification of Roflam F5 and 5 wt.% for aluminium hydroxide . The mass of ash (%) obtained from the combustion of the cured modified epoxy resin samples during thermogravimetric analysis for most of the epoxy modifications analysed was higher in relation to Epidian 5. The exception was sample 5F . Sample 5M was characterised by the highest value of ash mass (%) in relation to the single-component modifications, equal to 7.30%. Among the samples consisting of two additives, materials containing 5 wt.%. Roflam B7 + 10 wt.% Al(OH)-pyrenes . Anti-py-pyrenes ,44.2 were released. The CO concentration value increased over the test time of 600 s. The lowest CO value of 1721 ppm was recorded for sample 5M. This was 54% lower than Epidian 5. At the same time, the same sample had the lowest CO2 value of 30,751 ppm. After analysing the CO2 concentration, the time to the highest value for each modification differed. For example, sample 5F obtained the highest CO2 value of 35,389 ppm at the end of the analysis time. In contrast, the fastest maximum CO2 value, at 275 s, was recorded for the 10F + 5M sample, for which, at the same time, the CO value at the time of analysis was the highest. The lowest CO2 value of 22,931 ppm was characterised by sample 5B + 10A, while the highest CO2 value of 47,271 ppm was recorded for the cured unmodified epoxy resin.On the basis of the toxicity analysis of all the tested samples, CO and COmax and HRRav values of all fire-retardant modifications were lower compared to the corresponding HRR values of the unmodified Epidian 5 material .All the applied fire-retardant additives to the epoxy resin Epidian 5 effectively changed the fire properties of the epoxy materials tested. The heat release rate was reduced compared to the non-fire-modified material. The HRRThe solid-phase inhibitory effect of the applied flame retardants and their mixtures has been confirmed by the formation of layers of char.Applied anti-pyrenes containing phosphorus were found to be less thermally stable and have lower starting temperatures of thermal decomposition, but they exhibited multilevel thermal decomposition with higher efficiency of the carbonised residue.For samples 5F and 5B + 10M, the highest value of time to ignition of the gas phase was obtained (38 s). The main action of the additives took place in the solid phase. This was also evidenced by the higher residue values after thermal decomposition and combustion (by 76–790%) compared to the unmodified sample.The blended compositions had a lower onset temperature of thermal decomposition of the first phase compared to Epidian 5.The introduction of 5 wt.% magnesium hydroxide into Epidian 5 increased the initial temperature of thermal decomposition of phase I by 7 °C.Majority of the fire-retardant modifications of the epoxy resin were characterised by a higher ash weight (%) in relation to Epidian 5. The exception was sample 5F .The introduction of 5 wt.% magnesium hydroxide caused an increase in ash weight (%) in the thermogravimetric analysis to the highest differential level of 7.30%, as compared to all single-component flame-retardant modifications.2 were identified in the toxic gases included in the smoke from the combustion of the samples analysed, according to the research methodology selected for the study.CO and COThe concentration of CO (ppm) in thermal decomposition and combustion increased throughout the analysis lasting 600 s.From the research carried out and from the literature review, it was concluded that:


Hemoglobin is the main protein of red blood cells that provides oxygen transport to all cells of the human body. The ability of hemoglobin to bind the main low-molecular-weight thiol of the cell glutathione, both covalently and noncovalently, is not only an important part of the antioxidant protection of red blood cells, but also affects its affinity for oxygen in both cases. In this study, the properties of oxyhemoglobin in complex with reduced glutathione (GSH) and properties of glutathionylated hemoglobin bound to glutathione via an SS bond were characterized. For this purpose, the methods of circular dichroism, Raman spectroscopy, infrared spectroscopy, tryptophan fluorescence, differential scanning fluorimetry, and molecular modeling were used. It was found that the glutathionylation of oxyhemoglobin caused changes in the secondary structure of the protein, reducing the alpha helicity, but did not affect the heme environment, tryptophan fluorescence, and the thermostability of the protein. In the noncovalent complex of oxyhemoglobin with reduced glutathione, the secondary structure of hemoglobin remained almost unchanged; however, changes in the heme environment and the microenvironment of tryptophans, as well as a decrease in the protein’s thermal stability, were observed. Thus, the formation of a noncovalent complex of hemoglobin with glutathione makes a more significant effect on the tertiary and quaternary structure of hemoglobin than glutathionylation, which mainly affects the secondary structure of the protein. The obtained data are important for understanding the functioning of glutathionylated hemoglobin, which is a marker of oxidative stress, and hemoglobin in complex with GSH, which appears to deposit GSH and release it during deoxygenation to increase the antioxidant protection of cells. Oxyhemoglobin, an oxygen-bound form (HbFe2+-O2), and deoxyhemoglobin, an oxygen-free form (HbFe2+), contain iron in the reduced form (Fe2+). The structure of hemoglobin was first resolved and described by Perutz in 1970 [Red blood cells transport oxygen to body tissues with the help of hemoglobin, an oxygen-binding protein. Hemoglobin is a tetramer which consists of two alpha and two beta subunits, each containing a heme that binds one oxygen molecule. The hemoglobin molecule can be in three different states. The first one, methemoglobin, is characterized by its inability to bind oxygen and the oxidized form of FeThe hemoglobin concentration in erythrocytes is very high at about 5.5 mM, which is close to the solubility limit of this protein. Red blood cells have a limited supply of proteins, as they cannot synthesize proteins and are constantly exposed to various stress factors; therefore, a well-functioning antioxidant defense system appears to be crucial for this cell type. The significant part of this system is glutathione, the main low-molecular-weight thiol of erythrocytes, which protects proteins from irreversible oxidation. The redox potential of the reduced glutathione (GSH)/oxidized glutathione (GSSG) pair determines the redox potential of the cell . The conGlutathione is also able to covalently bind to the thiol groups of proteins, leading to glutathionylation, i.e., to the formation of an SS bridge between the glutathione molecule and the protein molecule. S-glutathionylation can be realized through different mechanisms , one of In this study, the effects of the formation of a noncovalent complex of hemoglobin with glutathione and glutathionylation of hemoglobin on the secondary structure of hemoglobin, the heme environment, conformation of the hemoporphyrin macrocycle, tryptophan fluorescence, and protein thermal stability were determined. The data obtained are important for understanding the mechanisms underlying the change in hemoglobin function during its covalent and noncovalent binding to glutathione.2—oxygen saturation, %) approaches 100% at an oxygen partial pressure above 17 kPa (128 mmHg) [2+ with O2) [The oxygen saturation of hemoglobin (SaOe 17 kPa 8 mmHg [1with O2) . The reswith O2) .Absorption and circular dichroism of hemoglobin in the Soret band region are caused by electronic transitions of hemes. It was found that glutathionylation did not affect the hemoglobin circular dichroism (CD) spectrum and the absorption spectrum in the Soret band region , indicatCircular dichroism spectra in the ultraviolet region reveal general changes in the secondary structure of globin. It was found that glutathionylation decreased in the proportion of alpha-helicity of the protein by almost 25%, increasing the percentage of disordered structures .The formation of the noncovalent complex of hemoglobin with GSH did not affect the secondary structure of the protein .The intrinsic fluorescence of hemoglobin is due to the presence of tryptophans and tyrosines in protein core ,15 or heThe intensity of tryptophan fluorescence of hemoglobin remained unchanged after the glutathionylation; consequently, the impact of glutathionylation on the intramolecular positions of tryptophans and the tryptophan environment is negligible .On the contrary, the formation of a noncovalent complex with GSH increased the intensity of tryptophan fluorescence , which eIn the previous work, we found that only Trp37.β was involved in the interaction with glutathione [Using differential scanning fluorimetry, we found that glutathionylation did not change the parameter characterizing the globin structure—the melting point of the protein. The formation of a noncovalent complex of hemoglobin with GSH led to a decrease in the melting point and, consequently, the thermal stability of the protein .The presented Raman spectra do not correspond to the spectrum of hemoglobin in solution, but in crystalline form when Raman is excited by a laser with a wavelength of 633 nm. Crystalline hemoglobin, that exhibits a resonant enhancement of a number of bands under 633 nm laser excitation, significantly affected the shape of the spectrum ,19.−1 (−1 (ν7)—symmetric deformation vibrations of pyrrole rings, and 745 cm−1(ν15)—“breathing” vibrations (symmetric stretching vibrations) of pyrrole rings [In these series of experiments with a noncovalent Hb + GSH complex, significant changes in the conformation of the porphyrin macrocycle were observed in the ratio of the bands of the CR spectrum: 665 and 745 cm−1 b, which le rings .−1 was smaller than for the other samples. This effect probably depends on the nature of crystal packing of the protein, since the resonance amplification is characteristic only for the dense packing of molecules in a crystalline sample [In the Hb + GSH samples, this ratio was less than in the control and in the Hb-SSG samples. Thus, in the samples with noncovalently bound glutathione, the resonance enhancement for band 665 cme sample ,19.−1 bands (−1 (ν46) corresponds to asymmetric stretching vibrations of CbC1 . The change in the conformation of the heme macrocycle is evident from the band 998 cm−1 (ν47) corresponding to asymmetric deformation vibrations of pyrrole rings. Both of these bands, according to the data of [In addition, differences were observed in the ratio of the 975 and 998 cm−1 bands c. The ba data of ,19, reso−1–2961 cm−1) [In these series of experiments, Fourier-Transform InfraRed (FTIR) spectra of hemoglobin were recorded  for the 61 cm−1) .−1–1243cm−1 (−1 corresponds to group vibrations of the amide bond in the protein molecule (Amide I); the greatest contribution to this type of vibrations was made by C=O vibrations. The maximum of the band is characteristic of the α-helical structure [−1 band corresponds to the group vibrations of peptide bonds of Amide II, including deformational N-H vibrations and valence C-N vibrations [−1 and 1393 cm−1 characterize the bending of CH2 groups and the symmetric stretching of CH3 groups, respectively [−1 –1312 cm−1, there was a lower-intensity region corresponding to the group vibrations of Amide III [Significant changes in the FTIR spectra during the formation of the Hb + GSH complex and Hb-SSG were detected in the region 1650 cm1243cm−1 . The bantructure ,22,23. Tbrations . The banmide III ,23, whic−1 [It is known that the position of the Amide I band changes with a change in the secondary structure of the protein. Usually, for a protein molecule, the shape of the Amide I band is determined by the superposition of the bands of all secondary structure elements included in the protein. For the alpha helix structure, the maximum usually localizes in the region of 1650 cm−1 . Hemoglo−1 . A decre−1  to estimp < 0.001) in the I1650/I1541 ratio for Hb-SSG relative to the control, indicating a decrease in the proportion of alpha helices in the protein molecule (−1 in the control to 1294 cm−1 in the Hb + GSH and Hb-SSG samples was observed. The I1294/I1243 ratio increased (p < 0.001) in the spectrum of the Hb + GSH complex and, to an even greater extent, in the spectrum of Hb-SSG  is located in an even shorter wavelength region compared to oxyHb. The absorption spectra of various forms of hemoglobin in the Soret region are characterized by the same maximum distribution as in the case of circular dichroism spectra.An increase in the affinity of hemoglobin for oxygen can be caused by a change in the position of the heme, since it is iron in the composition of the heme that directly coordinates oxygen during binding . ChangesWe found that a noncovalent complex of hemoglobin with GSH leads to a shift in the peak and a decrease in the amplitude of the peak in the spectra of circular dichroism and absorption in the region of the Soret band. This demonstrates a change in the heme environment due to conformational rearrangements during the formation of the complex. According to the literature data, a decrease in the amplitude of these peaks indicates contact with the ligand, and the shift in the peak to the short-wavelength region may be due to the exposition of the heme group from the crevices to the exterior part of the subunit ,31. RamaPreviously, we found  the bindUnlike the noncovalent complex of hemoglobin with GSH, which can be formed under normal conditions, Hb glutathionylation increases under conditions of oxidative  and metaThe quaternary structure of the deoxy form Hb contains salt bridges at the subunit interface, which were first identified by Perutz . In thisHemoglobin contains six cysteine residues, one each in the alpha subunits (Cys104) and two each in the beta subunits (Cys93 and Cys112). Currently, glutathionylation at Cys93β , and CysThe hemoglobin region containing Cys93 was studied in  using thCurrently, there is no comprehensive information on structural changes in the region of glutathionylated hemoglobin containing Trp37. However, according to the data obtained by the hydrogen/deuterium exchange method, glutathionylation of the oxy form of hemoglobin leads to an increase in conformational flexibility in this region of the molecule . At the Since the information on the possible glutathionylation of Cys104 is controversial and, according to our modeling data, Cys104 is not available for the solvent, for glutathionylation , the maiThe glutathionylation of hemoglobin increases in a number of pathologies . NormallThe obtained data are important for understanding the functioning of hemoglobin in erythrocytes, since the level of glutathionylated hemoglobin is significantly increased in various pathologies associated with the development of oxidative stress ,6, and tThus, it was found that the glutathionylation of oxyhemoglobin leads to a change in the secondary structure of the protein, reducing the proportion of alpha-helicity, but does not affect the heme environment, tryptophan fluorescence, or the thermal stability of the protein. During the formation of a noncovalent complex of hemoglobin with glutathione, the secondary structure remains almost unchanged; however, changes in the heme environment and the microenvironment of tryptophans, as well as a decrease in the protein’s thermal stability, are observed. Thus, covalent and noncovalent binding of glutathione to hemoglobin lead to various conformational changes. During the glutathionylation of oxyhemoglobin, despite the change in the secondary structure, there are no signs of a change in the tertiary and quaternary structure of hemoglobin, while the formation of a noncovalent complex has a significant effect on these structures.2HPO4, 15.2 mM KH2PO4, 2 mM MgCl2, pH 7.4) and reduced using 5 mM sodium dithionite for 10 min. The solution with reduced Hb was passed through a gel filtration column . Elution was performed using 50 mM K-phosphate buffer.Purified Hb solution was prepared as follows. Human metHb  (0.1 mM) was dissolved in 50 mM K-phosphate buffer  (4 mM) was allowed to interact with oxyHb to form a noncovalent complex, as described in . Oxy-Hb CD spectra were recorded on a Jasco J715 spectropolarimeter (Japan) at 20 °C. Two sets of wavelength ranges, 190–250 nm and 300–500 nm, were chosen for these studies. The 190–250 nm range was used to monitor the secondary structure. Hb samples at a concentration of 0.45 mg/mL were placed in quartz cuvettes of path length 1mm. The other range (300–500 nm), that spans the Soret region, was used for the detection of the structural alterations caused by heme. Quartz cuvettes of path length 1cm were used and the protein concentration was 0.3 mg/mL. All spectra shown are averages of 2 scans recorded at a scan rate of 100 nm/min. The spectra were corrected by subtracting appropriate buffer blanks. The measured UV spectra were resolved into components representing different types of secondary structure and their relative percentages were calculated using the program CDNN [Absorption spectra were recorded on Jasco v-550 spectrophotometer (Japan) in the range of 400–620 nm to detect the Hb states . Quartz cuvettes of path length 1cm were used and the scan rate was 100 nm/min. We estimated the efficiency of metHb reduction with sodium dithionite (Na₂S₂O₄) using the algorithm first proposed by . The metThe spectra of Hb-SSG and the noncovalent Hb + GSH complex, at a concentration of 14 μM, were recorded from 305 to 450 nm on a Cary Eclipse fluorometer (USA) with quartz cuvettes (path length 1 cm). Trp fluorescence was measured using 298 nm excitation [Nanotemper Tycho NT.6 (Germany) was used to measure the thermal stability of Hb-SSG and the noncovalent Hb + GSH complex. Hb at a concentration of 0.07 mM was placed in a volume of 10 µL in capillaries for measurements.The effectiveness of hemoglobin S-glutathionylation was assessed using Western blot analysis. After the incubation of hemoglobin with GSSG, a Tris-Glycine SDS sample buffer  was added without mercaptoethanol. Tris-glycine electrophoresis was performed in 14% of PAAG. Before incubation in a blocking buffer (5% milk), the membranes were fixed with a 5% formalin solution for 40 min to reduce the loss of alpha and beta Hb subunits (12–13 kDa). Primary mouse Anti-Glutathione antibody  was used for the detection of S-glutathionylated proteins and rabbit anti-human Recombinant Anti-Hemoglobin subunit beta/ba1 antibody  for the detection of Hb.The Raman scattering spectra of the sample were recorded using a combined confocal microscope–Integra Spectrum spectrometer . The registration parameters were as follows: laser, 633; power attenuation, 0.4ND; grating, 600; pre-exposure time to reduce fluorescence, 20 s; and spectrum registration time, 10 or 20 s. The Hb samples were dried as a drop on a mirror glass, and the spectra were recorded from the edge of the drop.The spectra were processed in the Spectragraph v program.1.2. The spectra were corrected by subtracting the baseline using the built-in algorithm; then, we normalized the spectra for the total area under the curve and determined the intensities of the exact bands.−1 with a scanning rate of 4 cm−1 4 times, and 4 spectra were measured from each drop. The obtained spectra were processed in Spectragraph 1.2. The spectra were represented as a dependence of absorption on the wave number.The infrared spectra of the IR Hb sample were recorded with a Spectrum Two FT-IR  IR spectrometer with attenuated total internal reflection infrared spectroscopy and internal reflection (ATR-FTIR). A drop of sample solutions in a buffer was dried on a slide and pressed against a zinc selenide window. The signal was recorded in the range of 550–4000 cmhttps://curie.utmb.edu/getarea.html (accessed on 22 August 2023)). SASA was calculated per individual residue using a probe with radius of 1.4 Å.The model of oxyhemoglobin in complex with 4 glutathione molecules construction was described in a previously published paper . The strp < 0.05. Values are shown either as means ± standard deviations or as boxplots with the minimum, the maximum, the sample median, and the first and third quartiles. The difference between the peaks of CD and absorption spectra in three groups was investigated with the Kruskal–Wallis test and Dunn’s test for multiple comparisons. The number of experiments and the p-values for each experiment are shown in the figures and in their captions.Statistical analysis was performed using GraphPad Prism. The Shapiro–Wilk test was used for checking if the data were normally distributed. An analysis of variance (ANOVA) was performed with the Tukey test for multiple comparisons to investigate the differences in several groups. Statistical significance was established as a value of It was established that the covalent attachment of glutathione to oxyhemoglobin—glutathionylation, which is increased under oxidative stress—causes changes in the secondary structure of the protein, but does not lead to significant alterations in its tertiary and quaternary structure. The formation of a noncovalent complex of hemoglobin with GSH, which occurs under normal conditions, on the contrary, has almost no effect on the secondary structure, but causes changes in the heme environment, tryptophan fluorescence, and melting temperature, indicating significant changes in its tertiary and quaternary structure.


The first case of virtual polymerization based on the concept of digital twins (DTs) is presented. The free-radical polymerization of vinyl monomers is considered to be a chain reaction consisting of a set of elementary ones. Those three types, related to the polymerization initiation and propagation as well as to the termination of polymer chain growth, are discussed. Special sets of DTs, whose total number approaches 60, distinguish each reaction type. The calculations are carried out using a semi-empirical version of the unrestricted Hartree–Fock approximation. The main energy and spin-density parameters of the ground state of the DTs are determined. The barrier profiles of two pairs of DTs are calculated, based on which two Evans–Polanyi–Semenov relations, attributed to elementary reactions of type (1) and (2), are constructed. These provide a quite reliable evaluation of the activation energy for the initiation and propagation of the free-radical polymerization of vinyl monomers in all the cases. The decisive role of spins in the formation of the elementary reaction transition states is established. Computational chemistry studies of polymers started as classical modeling more than 60 years ago and the field is currently considered as one of the most developed areas of chemical virtuality. Over the years, much progress has been made in polymer modeling, from a microscale view of the topic to intermediate-scale, mesoscale, and macroscopic-scale ones that were basic models for polymers’ quantum chemistry (QC) ,14,15,16Despite a deep contribution of computational chemistry to polymer science, there are not so many truly resolved issues. The high cost of calculations for models comparable to real systems, the limited capabilities of the available computational software and the lack of complex programs, providing simultaneous consideration of deterministic approaches such as thermodynamics, kinetics, and fluid mechanics, are all undoubtedly reasons for this. However, the exceptional complexity of polymers, which are the final products of multifaceted and multivariate intermolecular interactions, including a large number of participants, is also influential. The fate of a monomer that has fallen into the field of interaction of numerous participants can be figuratively represented as the state of a pineapple on a plant surrounded by sword-like leaves see . Each leThe polymer, as a material product, is the result of a choice made among the possible leaves around the fruit and the scales on its bark. Modern computational chemistry is unable to predict this choice. At best, the totality of all approaches, from micro-sized to macro-sized ones, makes it possible to explain the choice made either by Nature or by chemists thanks to their vast experience and intuition. In light of this, the two new concepts of the virtual approach to polymerization have attracted special attention. Actually, as it turns out, the DT concept has allowed the solving of a number of virtual chemistry problems that had not been solved before ,22. ThisFRP of vinyl monomers ,24 is atolecules .Real polymer products are produced in the conditions of the simultaneous implementation of all these events. Evidently, the virtual consideration of the total interactive community seems to be possible within the paradigm of quantum computing, satisfying the largest number of ‘given rules’, only . NeverthNaturally, this elementary-reaction-chain (ERC) approximation does not fully describe the complete polarization process. However, as history has shown, it is a reliable base for the QC analysis of the process, which makes it possible to reveal the mechanisms underlying it. The next steps towards the description of the final product s ReaxFF ,30, haveTraditionally, the thermodynamics of chemical reactions is quite fully described in the framework of transition state theory ,31 by a Here,  reviews ,13,14,15Numerous studies of the kinetics of various reactions have made it possible to reveal a significant simplification of the problem concerning reactions of the same type . As shown energy ,7,13, onHere products . Howevern method .In the current paper, the virtual FRP of vinyl monomers is considered in terms of the ERC approximation. The FRP thermodynamics will be presented with standard energy graphs related to sets (1)–(3) of the elementary reactions. The virtual FPR kinetics will be discussed in term of the activation energy A general paradigm of the DT concept can be presented schematically in  as 21,2,221,22.Here, DTs are the molecular models under study, the virtual device is a carrier of a selected software, and the IT product covers a large set of computational results related to the DTs under different actions in the light of the software explored by the virtual device. The quality of the IT product highly depends on how broadly and deeply the designed DTs cover the knowledge concerning the object under consideration and how adequate is the virtual device to peculiarities of this object. The first requirement can be met by a large set of relevant DTs. As for the virtual device, it should not contradict with the object’s nature and should perform calculations that provide reliable IT. Digital twins are completely free from the statistical and random errors that accompany real experiments, and are thus easy to modify. Came into the possession of a virtual device, DTs lay the foundation of a free independent virtual experiment in terms of the process of interest. As for the final IT product, an essential part of which is a comparative analysis of a large number of data produced under the same conditions, it mainly determines trends in the behavior of the object of interest.N-isopropylacrylamide—NIPA), n-butylacrylate—nBA), and •. The virtual device in the current study is the CLUSTER-Z1 software [In the current study, the DTs represent the reagents and final products of the elementary reactions shown in software ,34 implesoftware ,36. The software , graphensoftware , and stasoftware . A shortsoftware ,16,17,18software ,41,42. Nsoftware ,44,45). software , lays thThe IT product in the current study represents structural, thermodynamic, and kinetic parameters that, in terms of the universal energy graph, accompany the free-radical initiation of polymerization, a gradual transformation of the formed monomer radicals into oligomer ones in due course of the polymerization propagation followed by the growth of polymer chains, and the termination of the latter. The kinetic parameters are presented with the activation energy • in sp3C-C covalent bond.We begin our experiment on virtual the FRP of vinyl monomers by considering its first elementary reaction (1) related to the initiation. The largest systematic success in this area has been achieved when considering small molecules such as ethylene monomers and their derivatives in view of CI QC techniques ,7. When •, this algorithm reveals the central carbon atom, marked by red in the figure, as the most active, characterizing it by the fractional number of unpaired electrons e. The rest of the total number of radical unpaired electrons e is distributed over other carbon atoms  group of vinyls in both cases. These atoms, marked by red in sp2C-C bonds. The position of the vinyl bond over the benzene ring greatly stimulates the generation of the unpaired electrons at the sp2C-C bonds. The largest e is located on the carbon atom of the methylene (CH2) group of the vinyl bond. The rest of the total number of e is distributed over the carbon atoms of the benzene ring by e in average and over the rest one of the vinyl bond by e. The attachment of radical AIBN• to the benzene ring atom is highly unfavorable because of steric hindrance. Accordingly, the carbon atom of the vinyl CH2 group becomes the main target of the monomer for the radical initiation. • and the monomers.To solve this part of the problem, we use a unique spin-density algorithm of atomic chemical susceptibility (ACS), the ACS algorithm below, which makes it possible to visualize the distribution of effectively unpaired electrons of radicalized species over their atoms . Appliedtoms see . In monoicalized . AttachiRM1• to RM3•, generated by the attachment of radical AIBN• to the target atoms of the discussed monomers, are presented in e in both case) and on the bond of the methine unit in the case of e). The corresponding carbon atoms are shown in the figure in red and additionally marked with small black balls. Accordingly, the obtained Equilibrium structures of the intermolecular complexes related to the monomer radicals from n ND see . The maibond see c are att1 atoms refer to the target atom of the radical, C2—to the target atom of the vinyl group of monomers, and C3—to the remaining atom of the group. Thus, we obtain a possibility to present uniformly the atomic structure of the related intermolecular junctions as a combination of a single intermolecular sp3C1-C2 bond and double intramolecular sp2C2-C3 one. The unified first bond makes it possible to use it as a reaction coordinate when considering the barrier profile of the monomer radicals. In its turn, the second bond clearly reflects the positions of the previous and newly formed target atoms related to the vinyl bonds of the monomers. In contrast to the situation of the free monomers, the length of this bond is well above 3, as listed in CH2 or CH) around new targets only. As seen in the figure, the latter does not markedly affect the bond structure. In contrast, energy graphs are quite sensitive to the junction’s configuration.To simplify further the description, we denote the carbon atoms, which form intermolecular junctions between the radical and monomers, such that Csp2C-C vinyl bond from those with a set of the bonds. As will be shown later, this division on single-group and set-group monomers is fully approved concerning the FRP kinetics.ulations ,13,14,15The next four columns are related to activation energies, among which sp3C1-C2 bonds of the studied monomer radicals  point , indicating that the junction consists of a standard sp3C-C bond and elongated sp2C-C one. Because of the elongation, the double bond is radicalized [e, which causes the generation of the junction target atom C3 with e. The sp2C-C bonds, presented as an inset in sp3C-C bonds, the start of the sp2C-C bond radicalization occurs at sp3- and sp2-bonds, respectively.An attentive analysis of the transition states in both cases reveals a particular common behavior in spite of drastically different kinetics. First, attention is drawn to the value of the reaction coordinate corresponding to the maximum of the barrier profile. As seen in n ethane . As it ting bond  and prov 1.535,1.1, indicasp2C-C bond is only at the very beginning of its long way to breaking, while the started radicalization of the sp3C-C bond means the beginning of its breaking. The sharp threshold-like transition of the energy graphs around sp3C-C bond, will always occur at the bond length of 2.10 The reaction . It is o1 to C3 and playing the governing role in the case of the monomer radicals, are now extended to involving atoms C4 and C5. This part, discussed in the previous section, is changed because of the transformation of the sp2C2-C3 bond into a standard sp3C2-C3 one. The newly formed intermolecular sp3C3-C4 bond provides the connection of the monomer with the relevant monomer radical, while the intramolecular sp2C4-C5 bond takes the baton of the transfer of radical properties. The corresponding spin-density parameters of the dimer radicals are listed in 5 carbon atoms play the role of newly formed targets, aimed at holding a further polymerization. As for the energy parameters, in contrast to the monomer radicals, The first-step in the FRP propagation, the first elementary reaction of type (2) in sp3C3-C4 bond. Similarly to the previous case, the energy graphs are completed with equilibrium structures of the species and with their structures in the transition state as well as with a dissociated structure in the case of Repeating the consideration of activation energies, performed previously for the monomer radicals ite well ,49, as wite well ,50.sp2C4-C5 and sp3C3-C4 bonds. Since, as will be shown in the next section, the intermolecular junction at each subsequent step of polymerization is governed by the same combination of covalent bonds, the data listed in The main characteristics of the transition states of both dimer radicals are given in The presence of pairs of barrier profiles, related to the monomer and dimer radicals of monomers As it turns out, parameters n = 1, 2, 3, 4, … up to n = 8, 6, 7 for monomers n = 3, 6, and 8 are presented in n = 4, 5, and 7 are shown in sp3C-C bonds each, while the last one involves a pair of sp3- and sp2-bonds, the latter holding the newly formed target atoms. The line of atoms is accompanied by alternate methine and methylene groups. Attention is drawn to the bizarre weaving pattern of the oligomeric chain that differs drastically from regular chains straightened into one line, which abound in the presentation of linear polymers in articles and monographs. This circumstance is caused by the fact that each new addition of a monomer to the chain is accompanied by a change in the electronic configuration of the target carbon atom of the previous intermolecular junction, leading to the sp2sp3 transformation of the corresponding bond. The dramatic change in the valence angles under conditions of the obligatory avoidance of steric hindrance is extremely unfavorable for the rectilinear configuration of the clothesline, thus twisting it in such a complicated way. Let us continue the generation of oligomer radicals following the subsequent steps of the reaction n = 4 and 6 alongside with the relevant clothesline are presented in n = 2, 3, and 5 are shown in sp2C-C bonds also obey this algorithm. Thus, oligomeric radicals, presented in The radicals A full collection of the main spin-density and energy parameters of the designed oligomer radicals, starting from trimer ones, are presented in 2 (a) and C-CH (d) junctions, when presented with a standard sp3C-C bond, respectively. Two red-marked carbon atoms match the junctions in each case. The same junctions are observed if the radical 60 fullerene, and the monomer is substituted with an oligomer The third stage of linear polymerization, concerning the termination of the polymer chain growth and related to elementary reactions of type (3), proved to be the most complex. As previously, termination is governed by intermolecular interactions that couple the growing chain with other available species from the polymerization reactor. Evidently, the reactor content is very rich and is gradually replenished as polymerization progresses, starting with free radicals and extending over monomer, dimer, and other oligomer radicals. All these species can be coupled with the current chain, thus terminating its growth. Examples of stopping of this kind are widely described in a large number of monographs. Starting to analyze this stage virtually, we are faced with two serious problems. The first is the already mentioned richness of molecular participants in the reactor. The second concerns the great role of steric aspects. It is obvious that one should speak of a chain at the level of oligomer radicals with a sufficiently large sp3C-C bond between either two methylene (b) or methine (c) groups for single- and set-group monomers, respectively. The same contact structure is retained when one of the monomer radicals is replaced by an oligomer one, such as The second type of intermolecular contact occurs when monomer and oligomer radicals, belonging to the same monomer, are coupled to each other. As can be seen from the example of the two monomer radicals in the first row, the atomic structure of the intermolecular junction is an The intermolecular complexes shown in the figure reflect only a small number of the potential structures in the reactor. They are characterized by a significant scatter in the 60, as a replacement for the free radical 60 and C70 have been often considered as perfect templates for the chemical adsorption of large molecules [60 if steric hindrance is to be avoided.Fullerene Colecules ,52. Exciolecules ,53. Thesolecules ,56,57,58The discussion of virtual FRP proposed in this article rests on the presentation of polymerization as a chain reaction subdivided into successive elementary reactions. This vision allows the thermodynamics and kinetics of the reaction to be considered in the format of standard energy graphs. The implementation of the concept in the current study is based on the following conceptual grounds. First, the concept of digital twins, which is most suitable not only for the consideration of each such reaction, but also provides for their comparative analysis, highlighting reactions of the same type carried out under identical conditions. With a self-consistent approach to the choice of research objects (DTs), the virtual device, and the desired virtual intellectual product, a virtual experiment becomes a legitimized analogue of a real one, endowed with broad power. Over 60 DTs were considered in the current study. With such possibilities, we have carried out a rather full review of the entire cycle of the FRP of vinyl polymers related to its nanoscale aspect.The second conceptual issue concerns the dominant role of intermolecular interactions, which determine the inevitability of the all-with-all interaction between participants in the multicomponent basin of a polymerization reactor. Polymer formation is seen as a way to win the competition. The uniqueness of the controlling interaction gives rise to the uniqueness of the general algorithm of the polymerization process, based on the universal energy graphs that describe the energy component of the process at all stages.The spin-density algorithm of the UHF approximation, which makes it possible to obtain a numerical description of effectively unpaired electrons, is the third conceptual basis of the above consideration. This algorithm application first solves the problem of the adequate consideration of the open electronic shells of the radical reaction participants, and then confidently determines the positions of target carbon atoms within the initial and intermediate reagents, and establishes the governing role of spins in the localization of the transition state in the reaction coordinate system.The fourth conceptual element of the consideration results from the universality of the energy graphs mentioned above, which makes it possible to use barrier profiles, or the dependences of the total energy of the current polymer fragment on the reaction coordinate, for direct determination of the activation energy The close relationship between Following these principles, the virtual FRP of vinyl monomers can be described as follows. The field of competence of quantum-chemical consideration extends to linear chains of sequential oligomeric radicals with the number of chain links sp2C-C bonds in the monomer. So, alkene monomers The considered polymer chains represent oligomer radicals Oligomer radicals RM• is produced in the stage of the polymerization initiation, while all the rest occur in due course during the gradual polymerization propagation;The first link All the studied vinyl monomers form stable oligomer radicals characterized with a significant Spin-density and energy parameters can distinguish monomers by the number of the involved vinyl groups, thus dividing them into single-group and set-group monomers;sp3C-C bond, accompanied by methine and methylene units, while the remaining currently working one involves an elongated intramolecular sp2C-C bond, thus providing a target for radical attack;The structural composition of all the sp2sp3 transformation of the covalent C-C bonds, accompanying the clothesline elongation, combined with the resistance to emerging steric hindrances, has resulted in a bizarre, non-straight line image of the clothesline.A consequent The obtained thermodynamic characteristics of the considered DTs, which cover structural data and energy parameters concerning the ground state of the molecules, revealed the following common characteristics related to polymer chains and their members.Characterizing the transition state by RM1• and RM3• as well as The obtained profiles clearly distinguish single-group and set-group monomers, thus pointing to a different kinetics of the latter;sp3C-C bond of the current junction, at On the background of this difference, the transition state reveals a particular common feature related to the identical position of the profile maximum on the reaction coordinate, which is the intermolecular sp3 bond, the length of the junction intramolecular sp2C-C bond takes a value of 1.378 Å, which is sp2 bonds under elongation; Simultaneously, with a critical behavior of this sp3 and sp2 bonds, simultaneously indicates the spin-determining nature of the transition state of the vinyl oligomer radicals;Framing the energy parameter The obtained The obtained EPS relation, concerning the elementary reaction of type (2), laid the foundations for obtaining The The discussed trends are related to the initiation and propagation stages of free-radical polymerization, while revealing similar trends for the termination of polymer chains is still waiting for a particular algorithm.The kinetics of the oligomer radicals’ generation is considered in terms of the activation energy To summarize this part on activation energy in radical addition reactions, we can compare the obtained data with the following important factors which were reported to play a governing role in the barrier formation ,59.Reaction Exothermicity. The larger the The Singlet–Triplet Energy Gap, , of the Alkene. The smaller the Polar Effects. These effects lower