Degradable Vinyl Copolymers via Photocontrolled Radical Ring-Opening Cascade Copolymerization

Abstract

This dissertation discusses two main projects focusing on synthesizing degradable vinyl copolymers. The first project describes the development of a general approach to synthesizing degradable vinyl random copolymers through photocontrolled radical ring-opening cascade copolymerization (rROCCP). The rROCCP of a macrocyclic allylic sulfone with acrylates or acrylamides mediated by visible light at ambient temperature achieved near-unity comonomer reactivity ratios over the entire range of feed compositions. Such a powerful approach provides degradable vinyl random copolymers with comparable material properties to their non-degradable counterparts. Experimental and computational evidence also revealed an unusual reversible inhibition of chain propagation by in situ generated sulfur dioxide (SO2), which was successfully overcome by reducing the solubility of SO2 during polymerization. The second project depicts a general method for organocatalyzed photocontrolled radical copolymerization of a macrocyclic allylic sulfone and various types of vinyl monomers, including acrylates, acrylamides, styrene, and methacrylate. Catalyzed by Eosin Y under visible light irradiation, copolymerization of the macrocyclic allylic sulfone and acrylic monomers displayed near unity comonomer reactivity ratios by fitting the copolymer composition to the Beckingham-Sanoya-Lynd integrated model. The macrocyclic allylic sulfone was also successfully copolymerized with styrene or methyl methacrylate to generate degradable polystyrene and poly(methyl methacrylate). These degradable vinyl copolymers exhibited tunable thermal properties correlated with the incorporation of degradable main-chain diester motif.