Fabrication of submicrometer pores with an outer shell using modified poly(vinyl alcohol) and the molecular or particle collection effect.

ABSTRACT

Pores with an outer shell (POS) are fabricated on the submicrometer scale using modified poly(vinyl alcohol) (PVA). An aqueous solution is mixed with cationic PVA and a water-based colloidal suspension of polystyrene (PS) spheres of submicrometer diameter. The mixture is then spin-coated onto a substrate. The resultant structure is immersed in toluene, which dissolves the PS spheres. As a result, POS are formed by PVA on the substrate. By using PS spheres with 500 nm diameter, the pore openings have a diameter of about 300 nm and are surrounded by the outer shell. This structure exhibits beneficial molecular and particle collection effects, which are attributed to the peripheral shell rising from the surface. In addition, POS can be formed using a photo-cross-linkable PVA that is often used for enzyme-immobilized hydrogel matrices.