Assembled Surface-Anisotropic Colloids as a Template for a Multistage Catalytic Membrane Reactor

A polymeric catalytic membrane reactor (CMR) is fabricated using alternating assemblies of surface-anisotropic (sa-) and plain (p-) polystyrene (PS) colloids as a template. We report the preparation of TiO2 sa-PS colloids by physical vapor deposition of titanium onto a colloidal monolayer in an oxygen-rich environment and employ the modified colloids as a means to deliver the TiO2 catalyst to the CMR pores. sa-PS and p-PS colloids are assembled into alternating cylindrical sections inside a microcapillary followed by infiltration and curing of a liquid polymer precursor in the interstitial space of the assembly. Subsequent organic solvent treatment results in a cylindrical porous CMR with embedded TiO2 caps. TiO2 cap embedment, composition and surface morphology, surface pore structure, and cross-sectional integrity are analyzed using variable-pressure scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.