Surface Modification Of Inorganic Nanoparticles By Macromolecules

This dissertation deals with surface modification of inorganic nano-particles(nanometer silica, alumina and titania). The surface modifiers used include smallorganic molecules (diisocyanate, silane coupling agent, stearic acid,etc.) andpolymers (polyethylene glycol and polyether dendrimer).Polyethylene glycol (PEG) is successfully grafted onto nano-silica surface usingtoluene diisocyanate (TDI) as the coupling agent through a one-step procedure, underthe presence of catalyst dibutyltin dilaurate (DBTDL). The grafting mechanismsunder different reaction temperatures are also investigated. Compared with thosecommon used two-step procedures to graft polymer alcohol onto nano-particle surfacethrough diisocyanate coupling, this kind of one-step procedure is more simple andeffective.Small organic molecule carboxyl acids (stearic acid, benzoic acid and phenylacetic acid) are successfully grafted onto nano-alumina surface pretreated with3-aminopropyltriethoxysilane, through N, N'-dicyclohexylcarbodiimide (DCC)mediated amidation reaction in dichloromethane and other solvents. Furthermore, theeffects of carboxyl acid amount, carboxyl acid type and solvent type on the graftingare investigated. On that basis, polyether dendrimers with carboxyl group as the endgroup are used to graft nano-alumina surface. The results indicate that first generation(G1), second generation(G2) and third generation(G3)polyether dendrimers canall be grafted onto nano-alumina surface. This research may offer a general methodfor surface modification of nano-alumina.Two types of titania (rutile and anatase) are treated with toluene diisocyanate (TDI)and hexamethylene diisocyanate (HDI) respectively, and the surface property andreactivity of the titanias are analyzed. On that basis, the treatment of anatasenano-titania by HDI was further studied, the effects of HDI amount, reaction time andreaction temperature on grafting are investigated. Furthermore, anatase nano-titaniawas grafted with PEG using HDI as the coupling agent through a one-step procedure,under the effect of catalyst DBTDL. This work may serve as the basis for furtherstudy on surface modification of nano-titania.