Spin-Coated Periodic Mesoporous Organosilica Thin Films with Molecular-Scale Order within the Organosilica Wall

Abstract

Periodic mesoporous organosilica (PMO) thin films with long-range molecular order within the organosilica framework have been successfully prepared by spin-coating a solution of 1,4-bis(triethoxysilyl)benzene (BTEB), water, ethanol, HCl, and cetyltrimethylammonium bromide (CTAB) on silicon substrates. Powder XRD patterns of these thin films reveal the presence of a hexagonal phase mesostructure as well as ordered molecular-scale structure. The strong high-angle diffraction peaks indicate the long-range molecular order within the organosilica framework. The degree of organosilica condensation is relatively low, and hydroxyl groups formed in the hydrolysis reaction link the BTEB precursor molecules together in an end-to-end fashion via hydrogen bonding. Infrared spectra of these thin films suggest that the PMO films contain a significant number of hydroxyl groups in a hydrogen bonding environment with a peak at 3200 cm−1. Results from the 29Si magic-angle spinning (MAS) NMR spectroscopy provide additional e...