The Properties Of The Ionic Surfactant At The Solid/liquid Interface

A photosensitive surfactant is a special amphiphilic compound in response to the light stimulation.This kind of surfactants generally have an azobenzene group in their structure,and show different properties under the different light conditions.The surfactants have the potential application values in the molecular switch design,intelligent material preparation,drug release,material modification,etc.The adsorption behavior of the photosensitive surfactant in the quartz/water interface was studied.Firstly,thc surfactant,Azo,was prepared and characterized.The surface activity parameters of Azo were measured.Its wetting properties on the quartz surface was studied.The variation of the adsorption parameters was was explored,whch are the contact angle,adhesion force,adhesion work,solid-liquid interfacial tension and Zeta potential,etc.The adsorption behaviors of Azo at the gas/liquid and quartz/solution interfaces were studied.The isothermal calorimetric titrationand the nuclear magnetic resonance were used to study how a supramolecular form is formed between Azo and the cucurbit Q[7].The results show that they can enwrap each other at a 1:1 ratio,and a part of azobenzene group enters the cavity of Q[7].After UV irradiation,the azophenyl group breaks away from the cavity of Q[7].The effect of Q[7]on the cmc,A_min,Г_maxax was studied.The effect of Q[7]on the adsorption behavior of Azo on the quartz surface was discussed.The results show that after Q[7]is added,the contact angle decreases and the adhesion force increases and the interfacial tension decreases.The adsorption mechanism of Azo on the quartz surface was studied by QCM-D.In Azo solution,ΔF decreases with increasing time.After UV irradiation,ΔF andΔD decrease,and the adsorption membrane enhances its rigidity and its quality and thickness decrease.When the molar ratio of Q[7]and Azo is 1:1,azo-molecules cannot effectively adsorb on the quartz surface,and UV irradiation has no effect on the adsorption.When the molar ratio of Q[7]and Azo is 1:10,the values ofΔF andΔD exhibit to increase and the adsorption membrane enhances its rigidity and the quality and thickness of the adsorption film decrease after UV irradiation.