The Synthesis Of Amphiphilic Copolymer And Cellulose Modification By ATRP

Amphiphilic block copolymers remain the forefront of polymer science research in surface modification for medical materials,targeting drug carrier and other application areas,due to their special properties.The amphiphilic block copolymers with defined structure are usually synthesized by "living"/controllable polymerization,such as anionic polymerization,atom transfer radical polymerization and so on.And the "living"/controllable polymerization has been develop rapidly and it also has made structure controlling,molecular weight controlling and low PDI block copolymer synthesis come true.ATRP is becoming the most possible polymerization method which can be industrialized among all these "living"/controllable polymerizations.ATRP has its special strength in synthesis of block copolymer,since it can control the structure of copolymer more easily with lower PDI copolymer.All in all,ATRP has already become useful when homo-polymer and copolymer are synthesized with low PDI and modification treatment is made on the surface of some polymers.This paper mainly describes a way to synthesize bifunctional initiators by modifing hydroxypropyl dimethyl silicone.With these initiators,structure clear amphiphilic copolymer of PVP-PDMS-PVP and PDMAA-PDMS-PDMAA are obtained by ATRP.Our further purpose is to synthesize structure clear amphiphilic networks(APCNs)in future,which are two-component networks of covalently interconnected hydrophilic/hydrophobic phases of cocontinuous morphology.The study on modifying cellulose membrane by grafting PSt is also achived after binging the ATRP initiator group on the membrane.The main research is described as:1.Bifunctional ATRP initiators were synthesized in which hydroxy propyl polydimethylsiloxane and ethylene glycol were used as reagent,2-bromoisobutyrate and 2-chloropropionyl chloride as modifier.The temperature was controlled below 5? and the reaction time was 4h.The result shows that the initiators are synthesized in the reaction.2.The amphiphilic copolymers were synthesized by ATRP in which the initiator was synthesized as the first step,N,N-dimethylacrylamide and vinyl pyrrolidone were used as monomer.The effects of this reaction were researched in detail,such as solvent kinds,reaction temperature,reaction time and ligand kinds.From the result it is found that NVP can not reach high degree of polymerization when CuBr/Bpy is used as catalyst.For the synthesis of PDMAA-PDMS-PDMAA copolymer,the most important factors are solvent kinds and reaction temperature.As the polarity of solvent increases,the PDI of amphiphilic copolymer becomes lower and lower.As the temperature increases,the molecula weight of amphiphilic copolymer becomes higher,but PDI also becomes higher.DMAA is polymerized well at 70? in THF solvent,when CuBr/Me6TREN is used as catalyst.And the best molar ratio of catalyst is n[Cl-PDMS-Cl]:n[CuBr]:n[Me6TREN]?1:2:2.3.The hydrophobic modification of cellulose membrane was carried out by grafting PSt in which 2-bromoisobutyrate was used to react with the active hydroxyl on the surface of cellulose membrane.The ATRP initiator group was bringed into the membrane.Then styrene was polymerized on the surface of cellulose membrane.After that uniform PSt segments were graft onto cellulose membrane.The result shows that modification makes cellulose membrane,which is water uptake easily before modification,become hydrophobic.