Photochemical formation of hollow silicone microcapsule arrays on periodic microswelling structures of silicone rubber using 193 nm ArF excimer laser for microencapsulation of electrolytes

Microencapsulation for developing energy storage devices has been widely reported recently. In heat storage, many studies have been conducted to microencapsulate phase change materials with various shell materials. In contrast, there are still few studies on microencapsulation in power storage. In this paper, we found a new method to form hollow silicone microcapsule arrays for microencapsulation of electrolytes and suggested a new micropower storage application. Single layer of silica microspheres was formed on silicone rubber, then an ArF excimer laser irradiated the surface. Main chains of Si–O–Si bonds of silicone rubber underneath the microspheres could be photodissociated to lower the molecular weight, resulting in the formation of periodic microswelling structure of silicone rubber. Concurrently, a spherical microcapsule was also photochemically formed on each the microswelling structure. We systematically investigated the optimal conditions for chemical pre-etching to tune the gaps between microspheres to form spherical microcapsules and for chemical post-etching to completely remove the enclosed microspheres to form hollow microcapsules. The microcapsules formed consisted of silicone and were porous. Moreover, micro/nanoholes on the side/top of each microcapsule to encapsulate various electrolytes were successfully formed. The present results are expected to be applied as a micropower storage device that functions underwater. [Display omitted] •・A novel method for forming uniform hollow spherical silicone microcapsule array.•・Microcapsules with porous structure by deposition of low molecular weight silicones.•・Nanoholes for encapsulation formed at the top of each microcapsule.•・Microholes for encapsulation/connection formed on the side of each microcapsule.•・Suggestion of micro-electric double layer capacitors based on the present work.