Study Of Controlled Molecular Weight Size Of Polymers By ATRP In Ionic Liquid([AMIM]Cl)

Cellulose,as green natural polymer materials of the best application,has extensively used in biological and medical fields own to its advantage of excellent biocompatibility and biodegradability.It is possible to synthesize functional cellulose materials with designable molecular structure,adjustable molecular chain length and uniform molecular weight distribution（PDI,Mw/Mn）by atom transfer radical polymerization（ATRP）.Which has good application prospects in pharmaceutical chemicals and biological environment protection and so on.So in this papper,the ionic liquids that had strong dissolving ability of green solvent were used as reaction medium.The process of regulatory which the molecular weight size and its distribution of cellulose grafting molecular brush were explore by ATRP.The precise adjustment can be achieved which the molecular brush and molecular weight distribution of functional cellulose molecules,To fulfill the requirement in different fields.In this study,the narrow molecular weight distribution of poly methyl methacrylate（PMMA）was synthesized by atom transfer radical polymerization（ATRP）in the ionic liquid 1-allyl-3-methylimidazolium chloride（[AMIM]Cl）.Dibromo ethyl isobutyrate（2-Ebib）was used as the Initiator and CuBr/ethanediamine was the catalytic system.The chemical structure of PMMA was confirmed by the results of FT-IR.Polymerization conditions were explored on molecular weight and distribution of PMMA.Molecular weight size and molecular weight size distribution of PMMA were determined by GPC.The results showed that the molecular weight size of PMMA was mainly controlled by reaction time and concentration of initiator,The Mn of PMMA was 42380 and had a narrow PDI of 1.35 when the MMA/2-Ebib ratio was 10:0.35.However,the molecular weight size distribution of PMMA was controlled by solvent and catalyst system.Design of the molecular weight size and distribution of PMMA could carry out by optimizing the reaction conditions to achieve precise control of polymers molecular weight.The cellulose-graft-poly（ethylene glycol dimethacrylate）（cellulose-g-PEGDMA）molecule brush was synthesized by atom transfer radical polymerization（ATRP）using coordination ionic liquid[N₂C₂MIM]Cl/CuBr as a catalytic system in the ionic liquid 1-allyl-3-methylimidazolium chloride.The controlled mechanism of the graft polymer brush size and technology factors were investigated.The structure,molecular weight and molecular weight distribution of the polymer molecule brush were characterized by FTIR,¹HNMR and GPC.The results indicate that the reaction time,concentration of initiator and concentration of ligand were the main factors to control the length of the cellulose-g-PEGDMA molecule brush.The regulatory mechanism was preliminarily explored:the MCC-g-PEGDMA side chain molecular brush increase due to reducing of initiation point with reducing of the concentration of initiator;The ligand was the decisive factors in controlling the PDI of the molecule brush.The reaction mechanism of regulating molecular weight distribution was investigated.The[N2C2MIM]Cl/Cu Br as the catalytic system which can accurate regulate the length and distribution of functional cellulose polymer brush were achieved.The PDI of PEGDMA was precisely controlled at 1.1-1.4by using[N₂C₂MIM]Cl/Cu Br as the catalytic system.In addition,the MCC-g-PEGDMA self-assembly micelles were prepared in selective solvents N,N-dimethylformamide（DMF）.The self-assembly behavior of MCC-g-PEGDMA with different molecular weight and molecular weight distribution were investigatived by scanning electron microscopy（SEM）.The results show that the cellulose-g-PEGDMA copolymer with narrow PDI could aggregate and self-assemble into a sphere-like polymeric structure in solution.The size of polymer micelles increases with the increase of PEGDMA chain under the same PDI and side chain density,indicating that the obtained grafting copolymer has a promising potential in the drug delivery system.