Self-Assembly Synthesis of Mesoscopically Ordered Biphenyl-Bridged Organosilica Films with Molecular Periodicity in the Pore Walls

Abstract

Mild acidic one-step self-assembled synthesis of periodic mesoporous biphenyl-bridged organosilica films having hydrogen-bonded large molecular-scale periodicity in the pore walls from 4,4-bis(triethoxysilyl)biphenyl (BTSBp) and cetyltrimethylammonium bromide (CTAB) is successfully described for the first time. High resolution X-ray diffraction analysis (HRXRD) along with transmission electron microscope observation (TEM) revealed the formation of periodic mesophase with molecular periodicity in the pore walls. The nitrogen adsorption-desorption isotherm shows a type-IV isotherm with a pore diameter of 3.1 nm and a Brunauer-Emmett-Teller surface area of 714 m2g(-1). FT-IR and NMR spectroscopic data confirmed that biphenyl fragment is covalently linked with silicon atoms in final acidic-ethanol washed material. The obtained molecular-scale periodicity by structural model (1.389 nm) is consistent with experimental HRXRD value 1.40 nm. Nanoindentation hardness of biphenyl-bridged PMO films was found to be dependant on experimental conditions.