Siliceous mesocellular foams modified via a partitioned cooperative self-assembly process using hexane as pore swelling agent

Siliceous mesocellular foams (S-MCFs), a series of mesoporous silicas with large and 3D-interconnected mesopores, have drawn great attention as a versatile support for various applications. In this work, we for the first time demonstrated that hexane can be an ideal pore swelling agent for the preparation of modified S-MCFs (designated as MS-MCFs) via a previously reported partitioned cooperative self-assembly (PCSA) process based on cheap silica precursor, i.e., sodium silicate (SS). The MCF structures can actually be achieved by simply adjusting the addition order of the hexane with respect to the first addition of SS under certain partitioning conditions. As a result, conventional MCF structures can be modified by either disordered (PCSA-I route, hexane being added before the 1st addition of SS) or ordered SBA-15 (PCSA-II route, hexane being added some interval time after the 1st addition of SS) mesophases, forming two series of bimodal mesopore systems, without resorting to additives or complicated synthetic process. The specific surface areas up to 600 m2 g− 1, pore volumes up to 0.84 cm3 g− 1, and bimodal pore sizes (1st series measuring 8-12 nm and the 2nd series of 12-24 nm) can be obtained. The control over interval time, in particular in the PCSA-II route, during which the condensation of the silicate species was allowed to proceed was found to be crucial for the evolution of bimodal pore system other than the normal MCF structures, i.e., the formation of MS-MCFs. The silicate synthesis strategy thus reported opens new pathways to the preparation and tuning of MCF structured silicas and will further promote their applications.