Use of Hydrolysis-Robust Cyclic Vinyl Acetals in Radical Ring-Opening Emulsion Copolymerization

Abstract

Cyclic ketene acetals (CKAs) are often used in radical ring-opening polymerization (rROP) in solution and bulk polymerizations for the synthesis of functional degradable copolymers with ester breakpoints. However, CKAs are very sensitive to hydrolysis, which makes them unfavorable for use in aqueous emulsion polymerization. Therefore, monomers with improved hydrolytic stability are required that undergo rROP under emulsion conditions also giving cleavable breakpoints in the polymer backbone enabling degradability. In this study, we present two new cyclic vinyl acetal (CVA) monomers that we investigate in terms of their synthesis and homo-and copolymerization behavior with vinyl acetate (VAc) (a monomer frequently used in emulsion polymerizations) in emulsion polymerization. The rROP of CVA with VAc can provide cleavable functional groups (ketone, ether, and acetal) in the C−C backbone depending on the CVA structure and reaction conditions. The incorporation of such groups into the main chain opens a possible new way to degrade poly(vinyl acetate) (PVAc) in the future.