Study On The Surface Properties Of Cationic Surfactants Containing Azobenzene Groups And Their Adsorption At The Solid-liquid Interfac

Two kinds of responsive surfactants were synthesized using 4,4’-dihydroxyazobenzene,p-toluidine and phenol as the main starting material,and their molecular structures were characterized.We studied the effect of the light irritation conditions on the surface properties of the responsive surfactants.After UV irritation,the reactive surfactants（C₈-Azo-C₈and 4-QAS）undergo the photoisomerization,transforming from trans configuration to cis one,and the values of cmc,γ_cmcand A_minare increased,andΓ_maxandπ_cmcare decreased.We studied the effect of irritation conditions on the performance of responsive surfactants.After UV irritation,the contact angle of the surfactants decreases,and the adhesion force and adhesion work increase.When the concentration of the surfactant solution is increased,the foaming performance and the stability of foams are enhanced.When the surfactant reaches a certain concentration,the foaming height and the foam stability remain almost unchanged.After UV irritation,foaming properties and the foam stabilization appears to be decreased.The emulsifying properties of C₈-Azo-C₈and the differences of emulsifying properties before and after UV irritation were studied.The emulsification property is increased first and then is decreased,the emulsification performance is decreased and the demulsification rate of emulsion is increased.The interaction between C₈-Azo-C₈and CB[7]was studied by nuclear magnetic titration and UV-Vis absorption spectrum,and they could have a host-guest interaction with a ratio of 1:2.The hydrophilic group of C₈-Azo-C₈enters the cavity of CB[7].When the concentration of CB[7]remains to be unchanged,the influence of CB[7]on the surface tension and contact angle of C₈-Azo-C₈was studied.After adding CB[7],the surface tension of C₈-Azo-C₈is increased,and the contact angle is decreased,and the adhesion force and adhesion work are increased.The adsorption of C₈-Azo-C₈on quartz was studied using QCM-D and AFM.In the solution of C₈-Azo-C₈,ΔD value is less than 2×10^-6,and the adsorption film is rigid.When the concentration of C₈-Azo-C₈increases,the adsorption of C₈-Azo-C₈on the quartz surface increases.After UV irritation,the adsorption mass of C8-Azo-C8on quartz surface is decreased.UV light can make C₈-Azo-C₈desorb from quartz surafce.The adsorption of C₈-Azo-C₈on kaolin is decreased under UV irritation.The concentration Two-Step adsorption model accords with the kinetic process of adsorption of C₈-Azo-C₈on quartz surface.The adsorption and desorption of C₈-Azo-C₈on quartz surface can be controlled by illumination.According to the results of XPS and infrared spectra,C₈-Azo-C₈and 4-QAS can be adsorbed on quartz.This adsorption is physical adsorption.The flotation performance of C₈-Azo-C₈on quartz and collophanite was studied.C₈-Azo-C₈has strong flotation propertes for quartz,but weak flotation ability for collophanite is low.The flotation ability of C₈-Azo-C₈and 4-QAS to quartz and collophanite are decreased after UV irritation.