Photoinitiated RAFT Copolymerization of ?-Lipoic Acid and Acrylates for Degradable Polymers

Plastic pollution has rapidly escalated into a global challenge, with one major cause being the widespread use of traditional vinyl polymers. These polymers, with their entirely carbon-carbon backbones, are resistant to degradation and continue to accumulate in the environment. Our work focuses on sustainable polymer design by utilizing photopolymerization to create copolymers of acrylate-based monomers and α-lipoic acid (LA), a naturally occurring antioxidant. While prior work has explored copolymers of LA with vinyl monomers, LA copolymers have been prepared with a limited set of cleavable comonomers. In our work, we explored photopolymerization as a more versatile route to prepare LA copolymers. Using blue light irradiation, we can simultaneously initiate the ring-opening reaction of LA and controlled polymerization of vinyl monomers via reversible addition-fragmentation chain transfer polymerization, resulting in degradable polymers with controlled molecular weight and architecture. We systematically photoinitiator concentration, monomer feed ratio, reaction concentration, and polymer chain length, to better understand the unexplored mechanisms of LA-based copolymer photopolymerization. With synthesized LA-derivatives, we also achieved complex architectures such as hyperbranched, comb, and network structures via one-step polymerization. This work provides a simple and versatile approach to preparing degradable polymers, offering significant potential to reduce the environmental impact of plastic waste.