Porous microspheres of polyaniline, poly(o-toluidine), and poly(m-toluidine) prepared from double emulsions stabilized by toluidine isomers as the single surfactant.
HYPOTHESIS
Porous spheres of the conducting polymer polyaniline (PANI) and its derivatives are promising materials for use as functional encapsulants for payload delivery and catalyst supports. Stable water-in-oil-in water (W/O/W) double emulsions can be used to obtain this morphology, but typically require multiple surfactants and stabilizers. A single surfactant system that uses a small amphiphilic molecule is desirable, as it can simplify the method, improve its efficiency, and reduce its cost.


EXPERIMENTS
Granular poly(o-toluidine) (POT) was transformed into porous microspheres when ammonium hydroxide was added to an aqueous acidic dispersion containing the preformed polymer and amphiphilic o-toluidine (OT). The OT, POT, and ammonium hydroxide concentrations were varied to understand the formation mechanism. Conditions were optimized to obtain a narrowed size distribution.


FINDINGS
The rapid change from acidic to alkaline surroundings produces a W/O/W double emulsion from POT and OT over a relatively narrow concentration range. Spheres form when POT dissolves in immiscible OT droplets, and entrapped water droplets form the pores. OT serves as the single amphiphilic surfactant and dissolved POT serves as a hydrophobic co-stabilizer. o-Toluidine, m-toluidine, or p-toluidine could be used as the single surfactant to obtain porous spheres from preformed POT, PANI and poly(m-toluidine).
['Hwang|Jean J|JJ|', 'Soto|Carlos|C|', 'Lafaurie|Daniel|D|', 'Stephen|Moses|M|', 'Sarno|David M|DM|']
Porous microspheres Polyaniline Poly(o-toluidine) Poly(m-toluidine) Toluidine Single surfactant W/O/W double emulsions