Direct chromophore integration into polymer backbones via rhodanine step-growth chemistry

The precise spatiotemporal control of light-gated reactions makes photodegradable polymers highly attractive for designing materials that disintegrate on demand. Most synthetic strategies for incorporating photodegradable moieties into polymer backbones rely on the synthesis of monomeric building blocks containing photoreactive targets. However, this approach requires considerable effort, as the photochemical target must first be synthesized and then made compatible with the polymerization mechanism. Here, we introduce an efficient step-growth polymerization via the polyaddition reaction of rhodanine and isocyanide, in which photodegradable units arise directly from the polymerization process. The reaction of isocyanide with rhodanine generates enamine-substituted heterocycles with an extended conjugated system, rendering them photodegradable under visible light. As a result, the obtained high molecular weight polymers undergo rapid photodegradation under blue light or natural sunlight, efficiently depolymerizing in the presence of oxygen.