Kinetically Controlled Photoinduced Phase Separation for Hybrid Radical/Cationic Systems

Abstract

Controlling phase separation in polymer systems has shown significant promise in combining properties of different components into an integrated polymer system. In this work, we investigate the effect of photoinduced phase separation on polymer morphology and properties in hybrid radical/cationic systems composed of butyl acrylate (BA) and difunctional oxetane (DOX). We show that the irradiation intensity has a significant effect on the formation of phase-separated domains. By increasing the irradiation intensity at fixed co-monomer composition, the morphology changes from one with a continuous soft BA domain to one with co-continuous BA (soft) and DOX (hard) domains. At higher irradiation intensity, the domain size of each phase is decreased because of fast photopolymerization, which significantly limits monomer/polymer diffusion. The smaller domain size enhances the flexibility and strength of the phase-separated polymers. On the other hand, the irradiation intensity has little to no effect on the polym...