Synthesis Of Mesoporous Silica Nanomaterials And Their Applications In Catalysis And Drug Delivery

We synthesized a series of functional mesoporous silica nanoparticles (MSNs) by thegrafting method and the co-condensation method. All the mesoporous silica nanoparticlesremain the spherical morphology and are highly monodisperse.(1) The transition metal complexes on mesoporous silica nanoparticles possess excellentcatalytic efficiency in epoxidation of styrene when using tert-BuOOH (TBHP) as oxidant.Styrene shows a high conversion (⁹9%) as well as epoxide selectivity (⁸0%) over Cu-MSNcatalyst, and high conversion (⁹9%) and moderate epoxide selectivity (⁶5%) overMn-MSN and Co-MSN catalysts. The recycling experiment results indicate that thesecatalysts maintain catalytic activity even after being used for3cycles. Our results indicatethat MSNs can serve as better catalyst supports for the epoxidation of styrene.(2) We also synthesized nanocatalysts with different sizes (50-200nm) forpolymerization of1,3-butadiene (Bd) by immobilizing salicylaldimine cobalt complexes onthe mesoporous silica nanoparticles. The nanocatalysts in combination withmethylaluminoxane (MAO) show excellent catalytic efficiency in polymerization of 1,3-butadiene. The results reveal that these nanocatalysts also show higher activity than thehomogeneous analogue of cobalt complexes and the same catalyst on bulky mesoporoussilica supporting materials. The yield and the molecular weight of the poly-butadiene productdepend on the particle size of the catalyst support. This catalysis process is also a facile wayto directly synthesize the polymer/silica composite materials.(3) We synthesized a bifunctional mesoporous nanocatalyst. The nanocatalyst showshigh strong green photoluminescence upon irradiation with ultraviolet light. The catalyst alsoshows high activity for the polymerization of isoprene. This can produce a novel luminescentpolymer/silica composite, and this polymer/silica composite shows the samephotoluminescence as the nanocatalyst.(4) Functional mesoporous silica nanoparticles were synthesized by means of a one-stepsimple synthesis approach involving co-condensation of tetraethoxysilane andsalicylaldiminato complex (Sal-Si). We varied the size of the materials to obtain thenanoparticles with different sizes (50nm,100nm, and200nm, respectively). Furthermore, theCa²⁺cations also were introduced into the MSNs. The release of IBU from the MSNsfunctionalized by Ca²⁺cations is found to be effectively controlled as compared to that fromthe MSNs without functionalization of Ca²⁺cations.