Dynamically Switchable Global Chirality in Racemic Polymer Systems.

Abstract

Any polymers composed of racemic segments are obviously optically inactive and lack any chiroptical applications. Here, we present an intriguing method for precisely generating global chirality in racemic copolymer assemblies without any external asymmetrical intervention via step-wise polymerization-induced chiral self-assembly (PICSA). Global supramolecular chirality of the nanoaggregates could be dynamically switched by the two diametrically opposed chiral conflict effects: "first come, first serve" effect and "late-comer lives above" effect, which can be controlled by the precisely specified the number and sequence of enantiomeric segments. Significantly, the supramolecular stacking manners of the racemic mesogenic building units as well as the liquid crystallinity of the solvophobic core play a crucial role for the chiral communication pathway of enantiomeric mesogens. Furthermore, such switchable global chirality in racemic polymers is broadly applicable and well regulable. We propose that this research may challenge the notion that racemic systems lack optical activity while highlighting their potential applications in functional racemic polymer materials and providing insights into the evolution of racemates towards homochirality on early Earth.