Preparation of mesostructured siloxane-organic hybrid films with ordered macropores by templated self-assembly

Novel hierarchically ordered siloxane-based hybrid films with well-defined macropores and mesostructured pore walls have been prepared by the self-assembly process using oligomeric siloxane precursors bearing alkyl chains (CnH2n+1Si(OSi(OMe)3)3) in the presence of polystyrene opal films as a template. Either a two-dimensional (2D) hexagonal structure or a lamellar structure was formed depending on the alkyl chain length of the precursors (n = 10 and 16, respectively). In both of the films, the mesostructures were oriented along the spherical surface of the template and were retained after removal of the template. Calcination of the 2D hexagonal hybrid produced ordered porous silica with both macro- and microporosities. The lamellar hybrid film exhibited a unique property of accommodating alkyl alcohols with an expansion of the interlayer spacings. These results provide a new concept for designing hierarchical hybrid materials that are potentially applicable as adsorbents, catalysts, sensors, and photonic crystals.