Spontaneous Chiral Symmetry Breaking in Polydisperse Achiral Near-Rigid Nematogens

Understanding chirality transfer from the molecular to the macroscopic scale poses a significant challenge in soft and biological condensed matter physics. Many nanorods of biological origin not only have chiral molecular features but also exhibit a spread in contour length leading to considerable size dispersity. On top of this, random backbone fluctuations are ubiquitous for nonrigid particles but their role in chirality transfer remains difficult to disentangle from that of their native chirality imparted by their effective shape or surface architecture. We report spontaneous entropy-driven chiral symmetry breaking from molecular simulations of cholesteric liquid crystals formed from achiral bead-spring rods with a continuous spread in contour length and marginal chain bending. The symmetry breaking is caused by long-lived chiral conformations of long rods undergoing chiral synchronization leading to a homochiral twisted nematic. A simple theory demonstrates that even without chiral synchronization, the presence of shape-persistent configurational fluctuations of nonchiral objects with inherent size dispersity can be harnessed to bootstrap chiral synchronization.