Synthesis Of Branched Block Copolymer Via Vinyl Self-Condensing Polymerization (SCVP)

In this dissertation, a novel macroinimer, poiy(ethylene glycol)methacrylate-block-α-bromoisobutyryl poly(ε-caprolactone)(PEGMA-b-PCL-Br), was prepared by lipase-catalyzed ring-opening polymerization ofε-caprolactone and chemical modification of end groups. Self-condensing vinyl polymerization (SCVP) of this macroinimer via ATRP would generate branched block copolymer.First, Poly(ethyleneglycol)methacrylate-block-((ω-hydroxyl)poly(ε-caprolactone) (PEGMA-b-PCL-OH) was prepared by lipase-catalyzed ring-opening polymerization ofε-caprolactone with Poly(ethylene glycol)methacrylate (PEGMA) as the initiator and Novozyme-435 (lipase B from Candida Antarctica fixed by polyacrylate) as the catalyst. The effects of reaction time and initiator/monomer ratio on the structure of the obtained polymers were studied.Second, Poly(ethylene glycol)methacrylate-block-α-bromoisobutyryl poly(ε-caprolactone) (PEGMA-b-PCL-Br) was obtained by esterification ofω-hydroxyl group of PEGMA-b-PCL-OH withα-bromoisobutyrylbromide.At last, branched block copolymers were obtained via self-condensing atom transfer radical polymerization of PEGMA-b-PCL-Br in the presence of CuBr/2,2'-bipyridyl complex or CuBr/PMDETA complex. Adding methyl methacrylate (MMA) to the polymerization system resulted in branched triblock copolymers.