Free-standing and oriented periodic mesoporous organosilica films with variable pore size at the air-water interface

Free-standing and oriented periodic mesoporous organosilica (PMO) films with variable pore size have been synthesized at the air-water interface using cationic alkyltrimethylammonium surfactants (alkyl chain length from 12 to 18 carbon atoms) as the structure-directing agents and 1,2-bis(triethoxysilyl)ethane as the organosilica precursor. After hydrothermal reaction at 95 degrees C for 8 h, C(12)TA-PMO, C(16)TA-PMO, and C(18)TA-PMO films grown at the air-water interface have a uniform thickness of similar to 350, similar to 670, and similar to 400 nm, respectively. From the XRD patterns and TEM images, PMO films with hexagonal symmetry were identified. It was confirmed by Si-29 and C-13 CP MAS NMR experiments that the organic-inorganic moiety (-Si-CH2-CH2-Si-) is the basic structural unit in the films. The pore diameter and the surface area of the surfactant-extracted PMO films, e.g., C(12)TA-, C(16)TA-, and C(18)TA-PMO films, obtained from the N-2 sorption isotherms were to be determined to be 24.3, 26.4, and 32.8 angstrom and 890.3, 917.7, and 811.0 m(2) g(-1), respectively.