Self-assembled anionic micellar template for polypyrrole, polyaniline, and their random copolymer nanomaterials

Abstract

We report an anionic surfactant approach for size and shape control in polyaniline, polypyrrole, and their polyaniline-co-polypyrrole random copolymer nanomaterials. A renewable resource azobenzenesulfonic acid anionic surfactant was developed for template-assisted synthesis of these classes of nanomaterials. The surfactant exists as 4.3 nm micelle in water and self-organizes with pyrrole to produce spherical aggregates. The sizes of the spherical aggregates were controlled by water dilution and subsequent oxidation of these templates, produced polypyrrole nanospheres of 0.5 mu M to 50 rum dimensions. The anionic surfactant interacts differently with aniline and forms cylindrical aggregates, which exclusively produce nanofibers of similar to 180 mn in diameter with length up to 3-5 mu M. The template selectivity of surfactant toward aniline and pyrrole was used to tune the nanostructure of the anilinepyrrole random copolymers from nanofiber-to-nanorod-to-nanospheres. Dynamic light scattering technique and electron microscopes were used to study the mechanistic aspects of the template-assisted polymerization. The four probe conductivity of the copolymers showed a nonlinear trend and the conductivity passes through minimum at 60-80% of pyrrole in the feed. The amphiphilic dopant effectively penetrates into the crystal lattices of the polymer chain and induces high solid state ordering in the homopolymer nanomaterials.