Monodisperse Liquid Crystalline Polymer Shells with Programmable Alignment and Shape Prepared by Seeded Dispersion Polymerization.

Abstract

Monodisperse, micrometer-sized liquid crystalline (LC) shells are prepared by seeded dispersion polymerization. After polymerizing LC monomer mixtures in the presence of non-crosslinked polymer seeds, hollow LC polymer shells with programmable alignment and shape are prepared by removing the seeds. The LC alignment in the LC polymer shells can be easily manipulated by the polymer seeds, as a radial alignment is observed with amorphous poly(phenyl methacrylate) seeds and a bipolar alignment is observed with bipolar LC polymer seeds. After removal of the seeds, the radially aligned samples give radially aligned shells with small dimples. The resulting bipolar LC polymer shells collapse into a biconcave shape. Polarized optical microscopy and transmission electron microscopy indicate that the collapse occurs at the defect points in the shell. In the case of a lower crosslink density, LC polymer hollow shells with larger dimples are obtained, resulting in cup-shaped polymer particles. Biconcave LC polymer shells based on other LC mixtures have also been prepared, showing the versatility of the seeded dispersion polymerization method.