Organic-Functional Modification Of Mesoporous Materials And Its Application

In this dissertation, mesoporous silicas with the specific organic composition were prepared and their applications in the herbicide of alachlor delivery and as carrier of the catalytic center of chiral Salen-Mn(III) were carried out. The obtained results showed that the introduction of hydrophobic groups on the surface of mesoporous silica was very helpful to prolong the alachlor delivery time, and the immobilized chiral Salen-Mn(III) catalyst could be conveniently recovered for recycled use. The main contents discussed were as follows:(1) The herbicide of alachlor was incorporated into the channels of mesoporous silica M41 by using an impregnation wetness method. Surface hydrophobic modification of the assembly of alachlor-MCM-41 (Ach/M41), via a gas-solid reaction with 1, 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS), gave rise to an efficient sustained-release system (Ach/TMS-M41). The resulting Ach/TMS-M41 not only retained the high alachlor loading capacity but also possessed prolonged alachlor release time. The characterization results of XRD, Nitrogen adsorption/desorption, FT-IR and TG analysis showed that the M41 retained its structural integrity during the alachlor-loading process and that alachlor was dispersed completely in the channels of M41 with a mass fraction of alachlor [m(alachlor)/m(alachlor- M41)] as high as 0.381 g/g (27.6 % wt). The release properties of Ach/M41 and Ach/TMS-M41 in water were investigated. 62 % and 38.1 % of alachlor were released in Ach/M41 and Ach/TMS-M41, respectively, which indicated that hydrophobic modification of M41 is conducive to sustained-release of alachlor. Furthermore, the framework of the mesoporous silica protected the encapsulated alachlor against ultraviolet light irradiation.(2) Chiral Salen-Mn(III) active center was immobilized onto mesoporous silica by chemical linkage method and its performance in the asymmetric epoxidation of styrene was investigated. The effects of axial base, reaction temperature, and solvent on the catalytic performance of the heterogeneous chiral Salen-Mn(III) complex were investigated systematically. It was found that, under optimal reaction conditions, the conversion of the epoxide and the enantioselectivity were as high as 61 % and 42 %, respectively. Furthermore, the heterogeneous chiral salen-Mn(III) complex could be conveniently recovered for recycled use. Indeed the complex could be reused at least three times without significant losses of both activity and enantioselectivity.