Adsorption of a photoresponsive surfactant at the water–quartz interface: The role of UV irradiation and cucurbit[7]uril

Abstract

It is a challenge to develop a method of controlling the adsorption of small molecules at different interfaces. Here, we report the photocontrolled adsorption of a surfactant containing an azobenzene group (AZO) at the aqueous solution–quartz interface. The adsorption of the surfactant decreases at the interface and the corresponding adsorption layer becomes more rigid after UV irradiation. In addition, the adsorption of the surfactant at the interface is also decreased by addition of cucurbit[7]uril (Q[7]) due to the host–guest interaction between Q[7] and the surfactant. Adsorption of surfactant is stronger at the aqueous solution–quartz interface than at the aqueous solution–air one. The aqueous solution–quartz interfacial tension (γsl) of the surfactant is decreased by using UV irradiation or Q[7]. The adsorption mechanisms of the surfactant were investigated. Our study provides the methods to control the adsorption of the small molecules at the aqueous solution–solid interface.