Light- and mechanic field controlled dynamic soft matter materials

Abstract

We introduce a cyclic chemical system that can be remotely controlled by two distinct stimuli – light and mechanical force. Blue light at λ_max = 460 nm was used to convert a diazoketone moiety into a reactive ketene that can be caged by Staudinger cycloaddition to form a β-lactam mechanophore. The β-lactam moiety can subsequently undergo mechanochemical cycloelimination to release the reactive ketene, which can react with alcohols or amines to form esters and amides, respectively. Using this chemical system, we establish a reversible transformation of the polymer endgroup that is regulated by light and mechanical stimuli. Critically, we demonstrate the utility of our photo-mechanical chemical system in materials science by crosslinking and subsequently deconstructing polymer networks, controlled by blue light and sonication.