中文摘要：

通过可控/活性离子聚合方法设计合成一系列不同共聚组成的聚谷氨酸苄酯-g-（聚四氢呋喃-b-聚异丁烯）的新型嵌段接枝共聚物,即PBLG-g-（PTHF-b-PIB）,研究共聚物中支链（PTHF-b-PIB）长度及接枝密度对主链PBLG玻璃化转变温度、α-螺旋二级结构及其转变的影响,研究支链中PTHF链段长度对其双端受限的玻璃化转变及凝聚态结构的影响.结果表明：PBLG-g-（PTHF-b-PIB）共聚物中刚性主链保持α-螺旋二级结构;随着支链长度增加或接枝密度增加,主链PBLG的α-螺旋二级结构特征峰逐渐减弱,玻璃化转变温度逐渐提高,α-螺旋结构发生转变的焓值逐渐增大;在确定接枝密度的情况下,随着支链中PTHF链段长度增加,共聚物中双端受限的PTHF链段结晶逐渐增强,结晶熔融温度及熔融焓均增加;在确定支链中PTHF链段长度的情况下,随着接枝密度增大,支链间链段相互排斥,PTHF链段结晶逐渐减弱.

英文摘要：

A series of novel poly（γ-benzyl-L-glutamate）-g-（polytetrahydrofuran-b-polyisobutylene） graft-block copolymers, PBLG-g-（PTHF-b-PIB）, have been successfully synthesized via combination of living anionic polymerization with living cationic polymerization. The grafting density（GD） along PBLG backbone in PBLG-g-（PTHF-b-PIB） graft-block copolymers was mediated by changing the molar ratio of living-PTHF-b-PIB chains to ―NH― functional groups in PBLG backbone. The well-defined PBLG-g-（PTHF-b-PIB） copolymers with different grafting densities（GD）（9% ～65%） and different chain lengths（polymerization degree, DPb）（71.43～93.65） of-PTHF-b-PIB block segment branches were achieved. The chemical structure of the PBLG-g-（PTHF-b-PIB） copolymers was confirmed by FTIR, 1H-NMR and TGA characterization with grafting densities（GD） ranging from 9% to 65%. Circular dichroism（CD） and FTIR spectra showed that some of the PBLG-g-（PTHF-b-PIB） copolymers maintained α-helical structure from PBLG. The effects of GD and DPb of the-PTHF-b-PIB branches on the Tg, PBLG, α-helical secondary structure and enthalpy of α-helical transition of PBLG backbone were investigated by DSC. It has been found that the signal strength of α-helical secondary structure from the PBLG backbone gradually decreased while both Tg, PBLG and enthalpy of α-helical transition of PBLG backbone gradually increased with increasing GD or DPb in the branches. The effect of DPb on confined crystallization of PTHF segments in the PBLG-g-（PTHF-b-PIB） copolymers was also investigated by changing molecular weight of PTHF segments while keeping the same molecular weights of the PBLG backbone and PIB segments in branches. It was observed that both the melting point of the crystalline from PTHF segments（Tm,PTHF） and its melting enthalpy increased with increasing the molecular weight of PTHF segments in branches. Moreover, it is also shown that the crystallization of PTHF segments in PBLG-g-（PTHF-b-PIB） copoly