Microstructuring of Polystyrene Films by Template-Leaching Technique

Abstract

In this study, porous polystyrene membranes were prepared by a template-leaching technique. A suspension was first prepared by dispersing both polystyrene and starch in toluene, in which starch was used as leachable component. The weight ratio of starch/polystyrene ranged from 1:1, 1:2 to 1:3, whereas the concentration of the suspensions altered from 1%, 3%, to 5% by weight of polystyrene/toluene. After spin-coating the prepared suspension on the glass substrate, polystyrene/starch thin-film was produced, and then was treated with inorganic acid to remove starch components. The porous films with ordered and homogeneous structures were resulted. Analysis by contact angle measurement, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy analysis (FTIR) show that the microstructures on the porous films were affected by many experimental factors during the formation of thin-film and the following leaching process. Especially the type of the inorganic acid such as HCl, H2SO4, or HNO3, and the concentration of the specific acid selected in the leaching process have dramatic influences on the formation of the porous polystyrene membrane. The results further demonstrated that starch particles can be maximally removed when the films were immersed into the aqueous solution of HNO3.