SYNTHESIS OF ACRYLIC MACROMONOMERS BY FREE-RADICAL-INITIATED POLYMERIZATION - CONVERSION TO COMBLIKE COPOLYMERS

A versatile procedure was developed for synthesis of acrylic comblike copolymers in three steps: (1) Hydroxyl-terminated oligomers were synthesized from methyl methacrylate, butyl acrylate, and glycidyl (meth)acrylate by free-radical-initiated addition polymerization using a functional chain-transfer agent, 2-mercaptoethanol, and very low initiator levels. (2) The oligomers were converted to macromonomers by reaction with reaction with isocyanatoethyl methacrylate. (3) The macromonomers were polymerized by free-radical initiation. Conditions during the first step must be carefully selected to minimize formation of bifunctional materials, which could cause gelation during the third step. A variety of structures can be made such as comblike copolymers with homopolymer tines or comblike homopolymers with copolymer tines. Functional groups can be introduced by copolymerizing glycidyl (meth)acrylate into the macromonomer. Assignment of comblike structures is not rigorously proven but is strongly supported by the synthetic route and by DSC, FT-IR, and chromatographic data.