Gemini表面活性剂18-3-18/trans-ACA光敏胶束紫外光照过程流变动力学及界面流变性研究

UV Irradiation Rheo-kinetics and Interfacial Dilatational Properties of Gemini Surfactant 18-3-18 and trans-4-Phenylazo Benzoic Acid Composed Photo-Sensitive Micelle

研究了由Gemini阳离子表面活性剂丙撑基双(十八烷基二甲基氯化铵)(18-3-18)和反式偶氮苯-4-苯甲酸(trans-ACA)复配形成的光敏胶束新体系紫外光照过程的流变性质和界面流变性质,分别考察了光敏胶束浓度、紫外光照时间对胶束体系紫外光照过程流变性质的影响并建立流变动力学方程。结果表明:对18-3-18/trans-ACA(8mmol·L^(-1)/10 mmol·L^(-1))体系,随365 nm的紫外(UV)光照,光敏胶束体系黏弹性明显减弱,紫外光照500 s后体系复黏度减小92%;胶束浓度越大,体系黏弹性越强,紫外光照过程中体系黏弹性下降越慢;获得了流变动力学方程可表征光敏胶束弹性模量和复黏度随紫外光照过程的变化。进一步考察了稀释20000倍的18-3-18/trans-ACA(8 mmol·L^(-1)/10mmol·L^(-1))胶束溶液在不同光照条件下的界面扩张流变性。结果表明,该溶液经1 h UV照射后表面张力增大45%,界面扩张模量减小约32%,再经可见光照8 h后溶液界面流变性质可以恢复,首次证明其为界面流变性可逆的光敏表面活性剂溶液。

Rheo-kinetics during UV irradiation and interfacial dilatational properties of a novel photorheological(PR)micelle system was investigated.The photorheological micelle system was composed of a cationic Gemini surfactant propylene-(dimethyldioctadecylammonium chloride)(18-3-18)and a photo responsive counter ion,trans-4-phenylazo benzoic acid(trans-ACA).Effects of micelle concentration and UV irradiation time on rheo-kinetics during UV irradiation were studied,and rheo-kinetics equation was established.The results show that the viscoelasticity of the Gemini18-3-18/trans-ACA micelle system decreases with UV irradiation(365nm).The complex viscosity of the Gemini18-3-18/trans-ACA(8mmol?L?1/10mmol?L?1)micelle decreases by92%after500s UV irradiation.Moreover,the system has stronger viscoelasticity and slower viscoelasticity decrease rate when it contains higher micelle concentrations.A rheo-kinetics equation was obtained to characterize the change of elastic modulus and complex viscosity.Furthermore,the micelle concentration was diluted by20000times to study its interfacial dilatational properties under different irradiation conditions,and the results show that the surface tension increases by45%while the interface dilatational modulus decreases by nearly32%after1h UV irradiation.The interfacial properties can be recovered after8h visible light irradiation,which reveals that the solution is a photo-sensitive surfactant solution with reversible interfacial rheological properties.