Versatile Initiators for Macromonomer Syntheses of Acrylates, Methacrylates, and Styrene by Atom Transfer Radical Polymerization

Novel vinyl-containing initiators 2-vinyloxyethyl 2-bromoisobutyrate (VBIB) and 3-vinyloxylpropyl trichloroacetamide (VTCA) were synthesized for the preparation of vinyl-terminated macromonomers of different monomers by atom transfer radical polymerization (ATRP). Catalyzed by CuBr/hexamethyltriethylenetetramine (CuBr/HMTETA), the ATRP processes initiated by VBIB (for MMA, DMAEMA, and styrene) and VTCA (for MMA and DMAEMA) followed a first-order kinetics with respect to the monomer concentration. The molecular weights of the resulting polymers were very close to their calculated values and increased with the conversion. The GPC traces showed that the vinyl moiety in the initiators did not participate the polymerization at conversions below 80% during the ATRP processes of DMAEMA in bulk and those of MMA and styrene in γ-butyrolactone (γBL). VBIB also initiated methyl acrylate (MA) and butyl acrylate (BA) with first-order kinetics in the early stage of the polymerization; however, the process deviated from the first-order kinetics at high conversions due to reactions of the vinyl moieties. By terminating the ATRP of MA and BA at the early stage, the corresponding macromonomers were also obtained. 1H NMR confirmed that all polymer chains contained vinyl terminal groups derived from initiators.