Synthesis Of Block Copolymers Via Reversible Addition-Fragmentation Chain Transfer (RAFT) Living Radical Polymerization

The research interest of this thesis is concentrated on the two parts: (1) synthesis and characterization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) homopolymers via aqueous RAFT polymerization and their application in miniemulsion polymerization of methyl methacrylate (MMA) and styrene (St), respectively; (2) synthesis and characterization of 2-(dimethylamino)ethyl methacrylate homopolymers via organic solution RAFT polymerization, and their block copolymerization of stearyl methacrylate (SMA) in organic solution.(1) Synthesis of 2-(DimethyIamino)ethyl Methacrylate Homopolymers via Aqueous RAFT PolymerizationFor RAFT polymerization system, the effects of variations on the rate of polymerization, first-order kinetics, molecular weight and molecular weight distribution have been investigated. These variations included the concentrations of chain transfer agents (CTAs), concentrations of initiators, reaction time.The results of aqueous GPC analyses have confirmed that the molecular weights of the polymers produced were increased linearly with the conversions of the monomer. And the molecular weight distributions were in the range of 1.04 to 1.35, which was smaller than that of the theoretical limit of 1.5 for classical free-radical polymerization.On the base of upwards studies, poly(DMAEMA) as macro-RAFT agent, the block copolymerizations of DMAEMA and methyl methacrylate (or St ) were investigated in miniemulsion polymerization. Their structures were confirmed by ~1H NMR. Their latices morphology were tested by Hitachi H-600 transmission electron microscope, obvious core-shell were observed. And the latices diameter and distributions were determined by a dynamic laser scatter instrument.(2) Synthesis of 2-(dimethylamino)ethyl methacrylate homopolymers via an organic solution RAFT polymerizationHomopolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) have been synthesized directly in an organic solution by reversible addition-fragmentation chaintransfer polymerization (RAFT) using AIBN as the initiator and 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the chain transfer agent. The resulting polymers were controlled in the range of narrow molecular weight distributions and the molecular weights of the polymers produced were increased linearly with the conversions of the monomer.In addition, the produced dithioester-capped DMAEMA homopolymer using as a macro chain transfer agent, RAFT/solutions copolymerization of SMA were carried out. ~1H NMR analysis showed that the diblock copolymer PDMAEMA-Z?-PSMA was obtained as expected. Their molecular weights and molecular weight distributions were analyzed byGPC. It shows that both the Mn and PDI change before and after polymerization.