Effects of the Hydrophobicity of Substrate on Inverse Opal Structures of Poly(pyrrole) Fabricated by Colloidal Templating

Abstract

A colloidal templating method with vapor-phase oxidative polymerization was used to fabricate conducting poly(pyrrole) (Ppy) inverse opal patterns over a wide area. We fabricated 2- and 3-D Ppy inverse opal patterns from two kinds of 2- and 3-D colloidal templates of poly(St/NaSS) latex particle, which were prepared on bare glass and 3-aminopropyl trimethoxysilane (APTMS)-modified glass substrates, respectively. With two different 2-D colloidal templates, different Ppy inverse opal monolayer patterns, i.e., ordered 2-D rings, hexagonal or honeycomb monolayer, were obtained. With 3-D colloidal templates, Ppy inverse opal multilayers were obtained and their time-evolution growths were observed by SEM analysis. Differences in inverse opal structure and volume fraction were elucidated in terms of the array pattern of sacrificial poly(St/NaSS) latex particles and its packing density. Shrinkage of the inverse opal structure, which might be a serious problem in optical and physical properties, was reduced to almost zero with this method. Mechanical and electrical properties of the Ppy inverse opal multilayer films were analyzed by nanoindentation and four-point probe conductivity methods, respectively. It was found that narrow interparticle interstices of colloidal templates led to honeycomblike 2- and 3-D patterns, higher modulus and hardness, and lower electrical conductivity. In contrast, a spacious colloidal pattern resulted in 2-D ring patterns, hexagonal 2- and 3-D patterns, lower modulus and hardness, and higher electrical conductivity.