Light-Mediated Synthesis of Degradable Polymers With Complex Architectures Using α-Lipoic Acid as a Cleavable Comonomer.

The annual global production of polymeric materials is approaching 500 Mt, and the disposal and recycling of these polymers remains a significant challenge due in large part to the persistence of backbone carbon-carbon bonds, which require extreme conditions to degrade. A potential solution is to design polymers that are robust and stable during normal use but can be degraded on demand and enable new strategies for degradation and recycling. Herein, we present a versatile light-mediated synthetic approach to prepare degradable polymers, including both linear and nonlinear architectures. Our approach involves the controlled radical polymerization via reversible addition-fragmentation chain transfer (RAFT) of various vinyl monomers along with 1,2-dithiolane-based comonomers, which introduce disulfide bonds into the polymer backbone, enabling efficient degradation. Similar to conventional photoiniferter RAFT polymerization, light initiates the copolymerization and simultaneously generates thiyl radicals that react with growing chain radicals to propagate the polymerization. We demonstrate through the use of 1,2-dithiolane-functionalized inimers and selective excitation of CTAs that we can produce nonlinear polymers, including hyperbranched and graft polymers. This mild and versatile approach offers a promising strategy for designing and synthesizing degradable polymers with tailored architectures.