Self-Organization of an Amphiphilic Rod−Coil−Rod Block Copolymer into Liquid Crystalline, Substrate-Supported Monolayers and Bilayers

Abstract

We report that the amphiphilic rod−coil−rod triblock copolymer with a coil attractive to the substrate surface self-organize into liquid crystalline monolayers or bilayers of a few nanometers thickness on the substrate surface. The copolymer investigated is a triblock copolymer, poly(n-hexyl isocyanate-b-2-vinylpyridine-b-n-hexyl isocyanate) (PHIC-b-P2VP-b-PHIC). Key processes of self-organization in the thin films, such as adsorption, desorption, diffusion, nematic and smectic ordering, and microphase separation, are tuned by exposing dip- or immersion-coated nanoscale films to the vapor of solvents which are rod (PHIC)-selective, coil (P2VP)-selective, or good to both blocks. Reorganization of the rod−coils in the nanofilms yielded various morphologies in the monolayer or bilayer, including unique long-range-ordered, smectic-on-nematic biphasic sheets. The results offer understanding on the complex morphological evolution in amphiphilic rod−coil block copolymers on the substrate surface.