Periodic mesoporous organosilicas with helical and concentric circular pore architectures

This study systematically investigates periodic mesoporous organosilicas (PMOs) with controlled helical and concentric circular (CC) pore architectures prepared through a basic-catalyzed sol-gel process by using an achiral cationic surfactant trimethyloctadecylammonium bromide (C(18)TAB) as a structure-directing agent, perfluorooctanoic acid (PFOA) as an additive, and 1,2-bis(triethoxysilyl)ethane (BTEE) as a hybrid silica precursor. By increasing the weight ratio of PFOA/C(18)TAB, a pore architecture transition of PMO materials from hexagonal-arrayed, straight longitudinal channels to helical and CC mesostructures is achieved; such a transition has not been observed before in PMO materials. Our discovery is helpful in understanding the supramolecular cooperative assembly of hybrid materials and their structural and morphological evolution, which are important in the future applications of PMO materials.