光和热双重响应性rod-coil两亲分子的合成与溶液自组装行为  

Synthesis and self-assembly behavior of light and thermally responsive rod-coil amphiphile in aqueous solutions

作　　者：胡宗强 卢烁 董金凤[1] 李学丰[1] Zongqiang Hu;Shuo Lu;Jinfeng Dong;Xuefeng Li(College of Chemistry and Molecular Sciences,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学化学与分子科学学院,武汉430072

出　　处：《中国科学：化学》2023年第7期1265-1274,共10页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:22072109,21773174)资助项目。

摘　　要：本文合成了一种单链的非离子型rod-coil两亲分子TriBAzoEO,分子中的偶氮苯基团和聚氧乙烯醚头基分别赋予其对光和热的响应性.TriBAzoEO降低表面张力的能力有限,但在水溶液中会形成蠕虫状胶束.其浓度越高,蠕虫状胶束越长,体系的黏度越大.紫外光激发可将TriBAzoEO中的偶氮苯从反式变为顺式构型,诱导蠕虫状胶束向球形胶束的转变,但可见光激发不能实现逆转变过程,这可能与聚集体中顺式TriBAzoEO分子间存在较强的π-π相互作用及较大的空间位阻有关.TriBAzoEO水溶液具备热增稠现象,这种热可逆转变由聚氧乙烯醚头基与水分子间氢键作用的变化所引起.升温会削弱氢键而降低TriBAzoEO的亲水性,促进更大结构蠕虫状胶束的形成而导致热增稠;降温后TriBAzoEO的亲水性增强,蠕虫状胶束结构恢复,体系的黏度降低.In this work,a novel single-tailed nonionic rod-coil amphiphile TriBAzoEO was synthesized,in which the introduced azobenzene moiety and polyoxyethylene ether headgroup endowed it with light-and thermo-responses,respectively.The surface activity of TriBAzoEO was rather weak,whereas it formed wormlike micelles in the aqueous solutions.The increased concentration of TriBAzoEO resulted in the formation of wormlike micelles with longer length,and thereby endowing the sample with higher viscosity.The trans-to cis-isomerization of azobenzene moiety in TriBAzoEO was occurred under ultraviolet(UV) light irradiation,inducing TriBAzoEO wormlike micelles to spherical micelles transitions.However,the reverse transitions cannot be realized by visible light irradiation,which might be caused by the strong π-π interactions and steric hindrance between cis-isomers of TriBAzoEO molecules in aggregates.Thermo-induced reversible transitions of TriBAzoEO aqueous samples were mainly caused by the temperaturedependent hydrogen bonding interactions between polyoxyethylene ether headgroups and water.The hydrophilicity of TriBAzoEO would be decreased upon heating because of the weakened hydrogen bonding interactions,facilitating the formation of wormlike micelles with larger size and showing corresponding thermo-induced thickening behavior.Once the temperature was decreased,both the hydrophilicity and micellar structure of TriBAzoEO would be recovered,thereby resulting in the decreased viscosity.

关 键 词：rod-coil两亲分子 蠕虫状胶束 球形胶束 光响应性 热响应性 黏度 

分 类 号：O641.3[理学—物理化学]