Synthesis Of Poly[2-(n,n-dimethylamino)ethyl Methacrylate]-b-Poly(Acrylamide-Azobenzene)Copolymer By Raft Polymerization

In this thesis,poly[2-(N,N-dimethylamino)ethyl methacrylate]-b-poly-(acrylamide-azobenzene)(PDMAEMA-b-PAAAB)block copolymers were synthesized via reversible addition-fragmentation chain transfer(RAFT)polymerization,using 2-(N,N-dimethylamino)ethyl methacrylate(DMAEMA)and acrylamido-azobenzene(AAAB)as monomers,cumyl dithiobenzoate(CDB)as a chain transfer agent.The structures and performances of these polymers were characterized and determined.Firstly,CDB was synthesized by electrophilic addition reaction of?-methylstyrene and dithiobenzoic acid,which obtained from the acidification of dithiobenzoic acid brominated magnesium salt by hydrochloric acid.The dithiobenzoic acid brominated magnesium salt was prepared by the reaction of carbon disulfide and Grignard reagent formed from the reaction of bromobenzene and magnesium powder.The resulting CDB was characterized by 1H-NMR,FT-IR,and elementary analysis.The effects of solvent,temperature,dropping rate of bromobenzene,eluent and adsorbent used in column separation on yield of CDB were discussed.The results showed that the yield of CDB was up to 35.7%higher than that of literature reported(31.0%)and have high purity.Secondly,AAAB was prepared by the reaction of p-aminoazobenzene with acryloyl chloride.PAAAB was synthesized by RAFT polymerization of AAAB,using CDB as a chain transfer agent,AIBN as initiator,and DMF as solvent.The effects of reaction temperature,initiator and chain transfer agent concentration on the polymerization of AAAB were investigated.The resulting PAAAB was characterized by FT-IR,1H NMR,and GPC,and the thermal performence of PAAAB were determined by DSC amd TG The results showed that the kinetic curves of the polymerization reveal good linear relationship,and the molecular weight distributions were narrower;the polymerization rate,molecular weight and its distribution decreased with the[CDB]/[AIBN]ratio increases.The onset temperature of the thermal decomposition and the glass transition temperature(Tg)of PAAAB were 319.9? and 110.1?,respectively,which indicated that PAAAB has good thermal stability.Thirdly,PDMAEMA was synthesized by RAFT polymerization of DMAEMA,using CDB as a chain transfer agent,AIBN as initiator,and toluene as solvent.The effects of reaction time,temperature,initiator and chain transfer agent concentration on the polymerization of DMAEMA were investigated.The resulting PDMAEMA was characterized by FT-IR,1H-NMR,and GPC.The thermal performance of PDMAEMA was determined by TG.The results showed that the kinetic curves of the polymerization reveal good linear relationship,and the molecular weight distributions were narrower;the polymerization rate,molecular weight and its distribution decreased with the[CDB]/[AIBN]ratio increases.The onset temperature of the thermal decomposition of PDMAEMA was 309.1?,which indicated that PDMAEMA has good thermal stability.Finally,PDMAEMA was synthesized by RAFT polymerization of DMAEMA,using CDB as a chain transfer agent and AIBN as initiator.Then,resulting PDMAEMA was used as a macromolecular chain transfer agent for the systhesis of PDMAEMA-b-PAAAB copolymer using AAAB as monomer and AIBN as initiator by RAFT polymerization.The kinetics of AAAB polymerization was investigated,and the resulting PDMAEMA-b-PAAAB was characterized by GPC,1H-NMR and FT-IR.And the thermal performance and photoresponsive behavior of the block copolymer were determined by TG and UV.The results showed that the kinetic curves of AAAB polymerization reveal good linear relationship,and the molecular weight distributions were narrower;the onset temperature of the thermal decomposition of PDMAEMA-b-PAAAB were 262.3?,which indicated that PDMAEMA-b-PAAAB has good thermal stability.Photo-induced isomerization occurs for PDMAEMA-b-PAAAB,and the rate of isomerization and the recovery after equilibrium were slowly down with the increase of the molecular weight of PAAAB.