RAFT合成pH和温度响应的双亲水嵌段共聚物  

Synthesis of pH-and Temperature-responsive Double Hydrophilic Block Copolymer via RAFT

作　　者：彭志平[1,2] 程志毓[2] 漆刚[1] 

机构地区：[1]南昌大学材料科学与工程学院,江西南昌330031 [2]华南理工大学材料研究所,广东广州510640

出　　处：《精细化工》2011年第6期529-534,共6页Fine Chemicals

基　　金：第二批中国博士后科学基金特别资助项目(200902318);江西省教育厅青年科学基金项目(GJJ11028)~~

摘　　要：以S-十二烷基-S-′(2-羧基-异丙基)三硫酯(DDATC)为链转移剂,偶氮二异丁腈(AIBN)为引发剂,通过可逆加成-断裂链转移(RAFT)聚合合成了结构明确,窄相对分子质量分布(Mw/Mn=1.27)的聚(N-异丙基丙烯酰胺)-b-聚(N,N-二甲氨基甲基丙烯酸乙酯)(PNIPAm-b-PDMAEMA)双亲水两嵌段共聚物。共聚物的结构通过红外光谱、核磁共振氢谱和凝胶渗透色谱表征。采用透光率法、稳态荧光光谱法、电位滴定和动态光散射考察了PNIPAm-b-PDMAEMA在水中对温度和pH敏感的胶束化行为。结果表明,PNIPAm-b-PDMAEMA具有温度响应性,其水溶液的低临界溶液温度(LCST)为32.3℃,溶液温度高于LCST后发生温度诱导的胶束化,胶束的流体力学半径(Rh)为50 nm左右,Rh随温度升高而稍微增大;PNIPAm-b-PDMAEMA水溶液表现出明显的pH敏感性,25℃时两嵌段共聚物pH诱导胶束化的临界pH=9.8,溶液pH高于临界pH后发生pH诱导的胶束化,胶束的Rh约为31 nm(pH=11.0)。A double-hydrophilic diblock copolymer of poly（N-isopropyl acrylamide）-b-poly（N,N-dimethylamino-2-ethyl methacrylate）（PNIPAm-b-PDMAEMA） with well-defined structure and narrow molecular weight distribution（Mw/Mn=1.27） was synthesized via reversible addition-fragmentation chain transfer（RAFT） polymerization using S-1-dodecyl-S′-（α,α′-dimethyl-α″-acetic acid）trithiocarbonate（DDATC） and 2,2-azobisisobutyronitrile（AIBN） as chain transfer agent and initiator respectively.The PNIPAm-b-PDMAEMA was characterized by FTIR,1HNMR and gel permeation chromatography（GPC）.The pH and temperature induced micellization of PNIPAm-b-PDMAEMA in the aqueous solution was investigated by transmittance measurement,fluorescence spectroscopy,potentiometric titration and dynamic light scattering（DLS）.The copolymer exhibits temperature-responsive micellization in aqueous solution with a lower critical solution temperature（LCST） of 32.3 ℃.When the temperature was above LCST,the PNIPAm block became hydrophobic which caused formation of global micelle composed of PNIPAm core and PDMAEMA shell.The hydrodynamic radius Rh of the micelle measured with DLS was about 50 nm and increased with increasing temperature.The copolymer exhibited pH-sensitive associate behavior in aqueous solution and the threshold pH value of the pH-induced micellization was about 9.8 at 25 ℃.The Rh of the micelle composed of PDMAEMA core and PNIPAm shell was about 31 nm at pH=11.0.

关 键 词：可逆加成-断裂链转移聚合(RAFT) 双亲水嵌段共聚物 N-异丙基丙烯酰胺 N N-二甲氨基甲基丙烯酸乙酯 温度响应 PH敏感 功能材料 

分 类 号：O631.1[理学—高分子化学]