Templated synthesis of porous particles with tunable pore structures from nanoscale building blocks
Description
Porous silica, carbon, titania and carbon/silica composite micro- or nano-materials have been synthesized by the templated self-assembly approaches through an aerosol-assisted process or hydrothermal technique Porous silica particles with controllable hierarchical pore structure (from hexagonal to lamellar or hierarchical) have been prepared through tuning the hydrophilic and hydrophobic balance among silicate, cetyltrimethylammonium bromide (CTAB), and hydrophobic poly(propylene oxide) (PPO, H[OCH(CH 3)CH2nOH) additives during a dynamic aerosol-assisted process Aerosol-assisted self-assembly of hollow silica microspheres with microporous shell (HSMMS) are prepared by utilizing the block copolymer F127's aggregating behavior in basic solution and the self-assembly between silicate and amphiphilic tetrapropylammonium hydroxide (TPAOH) molecules. Interactions of TPAOH with both F127 and silicate are necessary for avoiding the phase separation between silicate and F127 aggregates because of the lack of hydrogen bonding interactions. Therefore, F127 aggregates with various sizes act as the core template while TPAOH molecules or TPAOH aggregates formed by excessive TPAOH molecules stay in the silica shell. Removal of F127 and TPAOH by solvent extraction results in the HSMMS materials Mesoporous carbon/silica composite with both meso- and molecular ordering has been synthesized by carbonization of as-synthesized phenylene/silica/surfactant hybrid by co-assembly of BTEB and Pluronic surfactant P123. Removal of silica from carbon/silica composite results in the mesoporous carbon which retains some of the meso-ordering and has many worm-like pores due to silica dissolution. This mesoporous carbon has potential applications in such field as hydrogen storage, catalysis, and other areas Hollow carbon microspheres with micropores in the shell and carbon nanotubes on the outer surface have been prepared using resols as the carbon precursor and hydrophobic PPO additives as template. An aerosol process with the heating temperature of 1000°C and an intermediate carbonization process result in the carbon material with the aforementioned structure Mesoporous titania materials with anatase wall are synthesized templated by nano-sized colloidal silica in an aerosol-assisted process. And titanate nanosheets are also obtained by treating materials with concentrated NaOH solution