Optical and morphological pattern formation of in situ created reactive polymer nanoparticles: Photopolymerization-induced phase separation and spatial reconfiguration

Configuring functional materials at nano- and micron-scales is pivotal, with liquid crystals (LCs) playing a crucial role in imparting molecular orientational order to these materials. This study explores the formation process of hierarchical polymer patterns with optical and morphological anisotropy through comparative analysis of patterning forces. Initially, a low-concentration reactive mesogen (RM) undergoes spinodal decomposition within the liquid crystal (LC), resulting in reactive polymer nanoparticles. Polymerization-induced phase separation further leads to the formation of intermediate polymeric nanoparticles. Subsequently, the randomly distributed reactive polymer nanoparticles undergo spatial and orientational reorganization based on the director configuration of the LC host, predominantly influenced by director distortion rather than dielectrophoretic forces or interfacial adsorption. This phenomenon is akin to the Pickering effect, with particles accumulating in high-strain regions to minimize system elastic energy. Importantly, the hierarchical pattern arises from reactive polymer nanoparticles generated during polymerization, rather than from individual RM molecules before polymerization. This innovative approach offers deeper insights into hierarchical pattern formation in functional materials, with potential applications in electronics and photonics.