Polymorphic Phase Formation of Liquid Crystals Distributed in Semicrystalline Polymers: An Indicator of Interlamellar and Interspherulitic Segregation

Amorphous and melted components can segregate into the interlamellar or interspherulitic regions of polymer crystals in their blends/mixtures; this phase behavior strongly influences the physical properties and functions of materials. However, it is experimentally difficult to evaluate the spatial distributions of the other components in polymer crystals. Herein, we use a small-molecule liquid crystal (LC) as a probe and find that it forms different solid phases when mixed with the semicrystalline polymer poly(L-lactic acid) (PLLA). The LC can form the metastable phase at the lower PLLA crystallization temperature but the stable phase at the higher PLLA crystallization temperature in the PLLA/LC mixture. The formation of LC metastable and stable phases is attributed to the segregation of the LC material in the interlamellar and interspherulitic regions of polymer crystals, respectively. This study provides a potential way to evaluate the spatial segregation in the crystallization-induced microphase separation of polymer blends/mixtures.