The preparation of self-ordered porous polystyrene film using auxiliary of ultrasonic fogging device

One of the methods to fabricate ordered micro-structured film is the usage of water droplets from humid-air flow as template. However, humid-air flow on the surface of polymer solution during cast of porous polymeric film may lead to uneven surface of the porous polymeric film. Moreover, the influence of atmosphere humidity on the average pore size of porous polymeric film is significant. In this study, we developed a novel method to fabricate even surface of porous polymeric film and reduce the influence of atmosphere humidity on the pore size. To achieve this purpose, an ultrasonic fogging device was employed to produce water droplets instead of humid air. The water droplets produced by an ultrasonic fogging device may contain negative ions to prevent the water droplets from aggregation. Therefore, the pore size of water droplets is able to be stabilized. In addition, the water droplets produced by an ultrasonic fogging device are able to fully fill in container in advance, which may avoid large humid-air flow to agitate the surface of polymer solution. Thus the even surface of porous polymeric film can be acquired.