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Abstract: Titania–silica composite nanoparticles were prepared by sol–gel-hydrothermal and sol–gel routes, respectively, and their physico-chemical and photocatalytic properties were compared. The results of XRD, TEM and BET surface areas showed that sol–gel-hydrothermal route led to anatase titania–silica composite nanoparticles with large specific surface area, but the sol–gel route tended to form mixture of anatase and rutile. The composite nanoparticles prepared by sol–gel-hydrothermal route had better thermal stability against phase transformation from anatase to rutile, agglomeration and particle growth than those prepared by sol–gel route. On the basis of XRD, FT-IR, XPS and 29Si MAS-NMR, a strong interaction was found between SiO2 and TiO2, and Ti–O–Si bonds formed during both the two routes. But more Ti–O–Si bonds formed in the composite nanoparticles prepared by sol–gel-hydrothermal route than those prepared by sol–gel route. As a result, the titania–silica composite nanoparticles prepared by sol–gel-hydrothermal route exhibited higher photocatalytic activity in decomposition of methylene blue than that prepared by sol–gel route, and it had excellent photocatalytic activity even after calcined at 1000°C. [Copyright &y& Elsevier]

Abstract: Dimethylsilyl (DMS) modified mesoporous silicas were successfully prepared via co-condensation and post-grafting modification methods. The post-grafting modification was carried out by the reaction of the as-synthesized MCM-41 material (before CTAB removal) with diethoxydimethylsinale (DEDMS). N2 adsorption–desorption and 29Si MAS NMR characterization demonstrated that different amount of DMS groups were successfully incorporated into the co-condensation modified samples, and the functional DMS groups were placed selectively on the pore openings and external pore surfaces in the post-grafting modified samples. Subsequently, the controlled drug delivery properties from the resulting DMS-modified mesoporous silicas were investigated in detail. The drug adsorption experiments showed that the adsorption capacities were mainly depended on the content of silanol group (CSG) in the corresponding carriers. The in vitro tests exhibited that the incorporation of DMS groups greatly retarded the ibuprofen release rate. Moreover, the ibuprofen release profiles could be well modulated by varying DMS modification levels and site-selective distribution of functional groups in mesoporous carriers. [Copyright &y& Elsevier]