Phase behavior, photopolymerization, and morphology development in mixtures of eutectic nematic liquid crystal and photocurable monomer

Abstract

Phase behavior and photopolymerization-induced morphology development in mixtures of eutectic nematic liquid crystals (LC) (designated E44) and photocurative monomers (designated NOA65) have been investigated by means of optical microscopy and light scattering. The observed phase diagram of the E44/NOA65 system prior to photopolymerization is of an upper critical solution temperature (UCST) type overlapping with the nematic–isotropic transition of E44. It displayed isotropic liquid, isotropic liquid+isotropic liquid, isotropic liquid+nematic, and pure nematic coexistence regions that were verified experimentally. Using the phase diagram as a guide, photopolymerization-induced phase separation experiments were performed in the isotropic region in order to examine the morphology development in multicomponent LC (E44)-based system in comparison with that of a single component LC (K21)-based system. Of particular interest is that the emerging LC droplets turned out to be unevenly distributed in the E44/NOA65 system as opposed to the K21/NOA65 system where the droplet size was uniform. The non-uniform distribution of the droplets in the E44/NOA65 system may be attributed to compositional fractionation associated with different affinities of the constituent LC in E44 to the NOA65 networks.