Superhydrophobic silicone microcup array on periodic microswelling structure of silicone rubber formed by 193 nm ArF excimer laser-induced photodissociation

Abstract

Many reports have been made on the study of imparting high functionality to materials surface by micro/nanofabrication of three-dimensional structures. In various three-dimensional structural geometries, the nanocups enable high-sensitivity analysis by combining with localized plasmon resonance. On the other hand, the formation of microcups and their applications have not been found much. In this paper, we found a new formation method of the silicone microcups and suggested its application. Single layer of silica glass microspheres was formed on silicone rubber, then a 193 nm ArF excimer laser irradiated the surface. Main chains of SiOSi bonds of the silicone rubber underneath the microspheres could be photodissociated to lower the molecular weight, resulting in the photochemical formation of periodic microswelling structure of silicone rubber. Concurrently, a hemispherical microcup was also formed on each the microswelling structure. The optimal laser irradiation conditions for their formation as well as the chemical etching time of microspheres were examined. It was also confirmed that the microcups are consisted of silicone. Moreover, the microcups exhibit superhydrophobicity. The results make it possible to confine the microcups in an air gap underwater, and it is expected to be applied as a micropower storage device that functions in seawater.