Polymer Membranes with Two-Dimensionally Arranged Pores Derived from Monolayers of Silica Particles

This paper describes a simple method to prepare porous polymer membranes with closely packed two-dimensionally arranged pores ranging from approximately 20 to 1000 nm diameter. Mixtures of hydrophobized silica colloids and a polymerizable organic liquid, trimethylolpropane trimethacrylate (TMPTMA), were spread onto the surface of water-filled containers to form a wetting layer, in which two-dimensionally closed packed silica particles are embedded in a layer of the organic liquid in such a way that they penetrate through both the upper and lower interfaces. Photochemical cross-linking of the organic monomer and subsequent removal of the colloids give rise to a polymer membrane with pores of uniform size. The crucial factor of this method is to spread exactly the amount of silica particles necessary for the formation of a closely packed two-dimensional monolayer.