Chirality Hierarchical Transfer in Homochiral Polymer Crystallization Under High-pressure CO2

Abstract

Abstract Ordered phase transitions are commonly correlated to the phenomenon of symmetry breaking, while disordered phase transitions are characterized by symmetry restoration. Nevertheless, this study demonstrates that the correlation between these factors is not always applicable in chiral polymers subjected to high-pressure CO2. In the absence of racemization, homochiral Poly(lactide acid) exhibits the formation of two dendritic crystals with opposite spiral chirality, resembling vortex shapes, as well as achiral crystals that resemble snowflakes. The transition from homochirality to achirality signifies the chiral symmetry restoration during the ordering process. The primary elements responsible for the hierarchical transfer of chirality from molecule to macroscopic crystal of chiral polymer are surface crowding and frustrated structures. The entropy impact of CO2 can be utilized to programmatically regulate the morphological chirality and crystal structure of two-dimensional crystal assemblies composed of chiral polymer.