Laser-assisted micro/nano-porous patterning with blowing agent on the surface of polyimide

Abstract

Porous polymer films have been investigated for various applications. The conventional method forms microporous structures throughout a film. This paper presents a new process for forming micro/nano-porous patterns on a polyimide membrane surface using a laser and a blowing agent only in selected areas. A blowing agent was mixed in a polyimide, and the mixture was then irradiated with a laser to instantaneously heat it to the decomposition temperature of the blowing agent. Subsequently, micro/nano-porous patterns were created only in regions irradiated with the laser owing to the explosion of the blowing agent. The micro/nano-porous patterns were fabricated using 355-nm ultraviolet pulse laser processing. The pores of the porous structures were closed or open, depending on the quantity of blowing agent, laser fluence, and pulse overlap ratio. The experimental results showed that the pore density, pore size, and processing time could be adjusted. In addition, porous patterning was formed selectively and locally. Recently, micro-/nano porous patterned films have been widely used as absorbents, support cells, and sensors in industrial fields and they have considerable application potential in various fields.