端糖基化聚（N-异丙基丙烯酰胺）的合成及其温敏性表征

摘要

Two kinds of derived carbohydrates（AcCDBr and AcGlABr） were synthesized as the initiators for atom transfer radical polymerization（ATRP） of N-isopropylacrylamide.The polymerizations of end-functionalized poly（N-isopropylacrylamide） with different saccharide groups（CD-PAM and GlA-PAM for short） were carried out using CuBr/tris（2-dimethylaminoethyl）amine（Me6TREN） as the catalyst system with the feed ratio of n[monomer]0∶n[initiator]0∶n0∶n[Me6TREN]0 = 50∶1∶1∶1 in DMF/water at 60℃.The structures of the initiators and the polymers were characterized by means of FT-IR and NMR.Low polydispersity indices（PDI = 1.12-1.20） were obtained by gel permeation chromatography（GPC）.Ultraviolet-visible spectroscopy（UV-vis） and differential scanning calorimetry（DSC） were employed to measure the lower critical solution temperature（LCST） of the end-functionalized PNIPAMs.The results showed the LCSTs of end-functionalized PNIPAM were increased due to the hydrophilicity of the saccharide groups,and the LCST of GlA-PAM was about 3.7℃ higher than that of CD-PAM.Furthermore,the end-functionalized PNIPAM showed an inverse molecular weight dependence of their cloud points.%制备了两种糖基引发剂（AcCDBr和AcG-lABr）,以CuBr/三-（N,N-二甲基氨基乙基）胺（Me6TREN）为催化体系,应用原子转移自由基聚合方法,在60℃下引发N-异丙基丙烯酰胺聚合,脱去乙酰基保护后得到末端分别带有β-环糊精和2-氨基葡萄糖基团的线形聚（N-异丙基丙烯酰胺）（CD-PAM和GlA-PAM）。对产物的结构进行了表征,凝胶渗透色谱（GPC）测得聚合物分子量分布较窄（PDI=1.12～1.20）。采用紫外-可见吸收光谱仪（UV-Vis）和示差扫描量热仪（DSC）对聚合物水溶液的相转变行为进行了测试,结果表明末端引入糖类结构使得PNIPAM的最低临界溶解温度（LCST）升高,并随着分子量的增大而降低,而且相同聚合度的GlA-PAM的LCST比CD-PAM的高3.7℃左右。