ORGS3-0039
Microscopic Origins for Solid-State Vibrational Circular Dichroism of Chiral Polylactide Crystals
When and Where
Nov 30, -0001
12:00am - 12:00am
Presenter(s)
Sheng Wei Shao (National Tsing Hua University)
Co-Author(s)
Abstract
Chirality transfer across multiple length scales (that is referred to as homochiral evolution) is an intriguing phenomenon widely observed in self-assembled systems including peptides, lipids, surfactants, liquid crystals, polymers and block copolymers. Herein, we aim to employ chiral polylactide as a representative system for the examination of the homochiral evolution from self-assembly at which chirality in self-assembled chiral polymers is classified into four levels: building unit of polymer with specific optical activity, polymer chain with preferred handedness, superstructure with exclusive helicity, and ordered phase with specific chirality. Herein, this work aims to examine the relationship between chiroptical responses and complex packing of helical polymer chains through simulation of first-principle molecular dynamics and experimental results of vibrational circular dichroism (VCD). An orthorhombic crystal structure of chiral polylactide is used to examine how interchain packing of helical polymer chain with specific handedness and collective vibrational coupling contribute to the VCD signals in the solid state. Ab initio molecular dynamics simulations can be performed under periodic boundary conditions, followed by VCD calculations based on nuclear velocity perturbation theory and time-correlation function analysis. By separating local and non-local correlation contributions, the observed VCD response originates not only from helical polymer chain with preferred handedness but also from cooperative interchain chiral interaction within the crystal lattice. The results provide molecular-level insight into chirality amplification in crystalline polymers and establish a computational framework for understanding hierarchical chirality in self-assembled soft materials.
