Baylis-Hillman Reaction as a Versatile Platform for the Synthesis of Diverse Functionalized Polymers by Chain and Step Polymerization

The Baylis-Hillman reaction, which is a carbon-carbon bond forming reaction between an aldehyde and an activated alkene, was utilized to prepare densely functionalized monomers suitable for chain and step polymerization. By reacting formaldehyde with various alkyl acrylates, a series of alkyl alpha-hydroxymethyl acrylate monomers were synthesized. These monomers efficiently underwent RAFT polymerization to provide alpha-hydroxymethyl-substituted polyacrylates with well controlled molecular weight and low polydispersity. The resulting homopolymers were also efficient macro-chain transfer agents for further RAFT polymerization. The Baylis-Hillman reaction was also utilized to synthesize alkene functionalized diols which underwent step-growth polymerization to provide polyesters and poly(ester urethane)s. Furthermore, it was demonstrated that the alkene group can be quantitatively functionalized by thiol-ene click chemistry to provide a series of polymers with diverse physical properties.