Microstructural Characterization of Polystyrene-<i>block</i>-poly(ethylene oxide)-Templated Silica Films with Cubic-Ordered Spherical Mesopores

Abstract

We report the synthesis and characterization of mesostructured thin silica films derived from methyltriethoxysilane (MTES) and/or tetraethyl orthosilicate (TEOS) silica precursors and polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers via the solvent evaporation-induced self-assembly (EISA) process. It is found that the meso- and microstructure of the calcined films consists of cubic-ordered arrays of spherical mesopores of 5−7 nm in diameter, interconnected with a small number (≤4% by volume) of PEO-induced micropores of ∼1 nm in diameter, as determined by new experimental results of transmission electron microscopy, N2 sorption, gas permeation, and grazing incidence small-angle X-ray scattering studies. The present comprehensive study of these novel closed-pore films should provide a general methodology for microstructural characterization of other related porous films prepared by similar self-assembly processes.