PVAc-b-PMMA Copolymers Prepared By Living Radical Polymerization

A novel method for preparation of PVAc-b-PMMA was studied. This thesis consists of two steps: 1. I2 was added to conventional polymerization system of VAc, the resulted PVAc chains were terminated with living–I group (PVAc-I); 2.PVAc-I was used as macroinitiator of ATRP in the polymerization of MMA to form block copolymer.1. Reversible Iodine Transfer Polymerization (RITP) of VAc with presence of I2:Polymerization system consists of three components: VAc,I2 and AIBN. I2 firstly reacted with AIBN under heat and generated a new iodide:α-iodoisobutyronitrile, which worked as transfer agent in the system and subsequently the polymerization process was well controlled, the polydispersities of produced PVAc were narrow. Molecular weights of PVAc tested by GPC were close to the calculated ones and with living–I end group, these macromolecules can be potentially used as initiators of ATRP.2. ATRP of MMA initiated by PVAc-IATRP of MMA with PVAc-I as macro initiator, three catalyst/ligand systems were studied: CuCl/PMDETA, CuCl/MA5-DETA and FeCl2?4H2O/PPh3 .The linear proportionality of the molecular weights to the conversions and straight lines observed in Ln (M0/Mt) (where M0 and Mt represent the monomer concentration at beginning and at any time respectively) versus time plots indicated typical controlled living polymerization characteristics. ATRP of MMA using PVAc-I with different molecular weight as initiators were studied, with the increase of molecular weight of PVAc-I, both the monomer conversion of MMA and initiator efficiency decreased.The polydispersities of the obtained block copolymer were around 1.4 to 1.8. The analysis of 1H NMR and GPC traces of obtained polymer confirmed PVAc-I was a fine initiator for ATRP, and this method was a successful way to prepare PVAc-b-PMMA block copolymer. 3. Degenerative Polymerization of MMA with PVAc-I as macro transfer agentAIBN, MMA and PVAc-I was added in a tube and reacted under RITP mechanism, in which PVAc-I was designed as macro transfer agent. We tried to synthesis PVAc-b-PMMA copolymer through the transfer of PVAc·to PMMA·. The experiment results indicated that it was difficult to form PVAc-b-PMMA by this way.4. Star shaped PVAc prepared by the reaction between PVAc-I and multifunctional aminePVAc-I prepared by RITP method were with active–I end group, we designed to synthesis star-shaped PVAc by the reaction between PVAc-I and multifunctional amine. After the RITP of VAc, amine was injected into the tube directly under stirring. Experiment results indicated that star-shaped PVAc could not synthesize by this method, it may because the reaction between–I and amine was difficult to happen or the star-shaped PVAc were easy to decompose.