(177v) Light-Mediated Synthesis of a-Lipoic Acid (LA)-Based Bottlebrush Polymer

Bottlebrush polymer are comb-like molecules composed of a linear polymeric backbone with densely grafted side-chains. The unique structure of bottlebrush leads to distinctive properties, making them widely used in super soft elastomers, photonic crystals, and drug delivery. However, the expensive reagents, complex synthesis, and lack of degradability impedes further commercialization. To address these challenges, we introduce a versatile polymerization method to synthesize degradable bottlebrush polymer based on lipoic acid (LA). Lipoic acid is a naturally occurring and commercially available molecule with a disulfide bond in its 5-membered ring. We first functionalized LA with an initiator for atom radical transfer polymerization (ATRP), allowing the polymerization of a variety of methacrylates through ATRP. By exposing the macromonomers to ultraviolet (UV) light, the disulfide linkage in LA is subsequently cleaved and undergoes ring opening polymerization and form degradable backbone of bottlebrush polymer. Notably, these bottlebrush polymers can be easily depolymerized in addition of reducing agents. With established mechanism, we further tailor the structure of bottlebrush polymer by investigating the effects of concentration, solvent, and length of macromonomers. To investigate the potential applications, we conducted copolymerization of the bottlebrush with diacrylate linkers, leading to the successful preparation of self-healing materials. These results demonstrate a simple route to synthesize dynamic bottlebrush polymer at ambient temperature, offering prospects for inexpensive and sustainable polymeric materials.