Selectively Regulating Asymmetric Photopolymerization Via Competition Between Circularly Polarized UV and Visible Light

Circularly polarized light (CPL) has attracted considerable interest since it can impart chiral bias into photochemical reactions and open up a novel opportunity for synthesizing chiral polymer materials. Despite numerous reports describing the chiral induction effect with single CPL, the synergistic or competitive effect between two types of CPL-i.e., circularly polarized ultraviolet light (CPUV) for triggering asymmetric polymerization while circularly polarized visible light (CPVL) only for accelerating helical chain propagation-is rarely reported. Here, this work demonstrates that the selective regulation on the asymmetric photopolymerization can be realized by the arbitrarily coupled irradiation with CPUV and CPVL, either constructively or destructively. In the former case, further chirality amplification can be achieved. Remarkably, for the latter case, the opposite handed CPVL can bias the polymer helicity during the chain propagation process and thereby overrule the helical preference inducted by CPUV. This work highlights the importance of chiral induction effect in helical chain propagation process and is highly valuable for deeper understanding of helical preference in CPL-triggered asymmetric photopolymerization.

Automated summary

This study demonstrates that selective regulation on asymmetric photopolymerization can be achieved by the arbitrarily coupled irradiation with CPUV and CPVL, either constructively amplifying chirality or destructively changing the helical preference of polymer chains. The work highlights the importance of the chiral induction effect in the helical chain propagation process and provides a deeper understanding of the helical preference in CPL-triggered asymmetric photopolymerization.