Silica compositions

POLYELECTROLYTE-SILICA COMPOSITE FILMS USING SURFACTANT FEATURE ... 

J. N. Kinkel, Optically active polyacrylamide/silica composites and related packings and their application to chiral separations in A practical approach to chiral separations by liquid chro-matogratphy, G. Subramanian, VCH, Weinheim (1994) Chapter 8. 

Preparation of chitosan-zeolite composites by zeolitisation of a chitosan-silica composite... 

A preformed chitosan-silica composite with 60% weight inorganic part [7] is used as the source of silica for the zeolite synthesis. An alkaline solution of sodium aluminate (Na 2.1 M, Al 1 M) was used in three methods of preparation (A) beads of the chitosan-silica composite were stirred overnight in the aluminate solution, extracted and submitted to a hydrothermal treatment at 80 °C during 48h (B) beads of the chitosan-silica composite were immersed in the aluminate solution and the system underwent a hydrothermal treatment at 80 °C for 48h (C) beads of the chitosan-silica composite were stirred overnight in the aluminate solution, extracted, dried at 80 °C and exposed to water vapour at 80°C during 48h. 

S. Sampath and O. Lev, Renewable, reagentless glucose sensor based on a redox-modified enzyme and carbon-silica composite. Electroanalysis 8, 1112-1116 (1996). 

If one examines the evolution of new zeolite structures over the past decade the most interesting discoveries have been made with high silica compositions. Many of these phases can be prepared in essentially all silica forms. Purists would prefer to classify such molecular sieves as organosilicates or porosils (1), in part because the physical properties differ from more classical low Si/Al ratio zeolites. In particular, the high silica zeolites tend to be more thermally stable and chemically robust. Additionally, the higher the Si/Al ratio the more hydrophobic the zeolite. These features are desirable for catalysts that may be used in catalytic processes such as cracking (3). 

Nguyen T-Q, Wu J, Doan V, Schwartz BJ, Tolbert SH (2000) Control of energy transfer in oriented conjugated polymer-mesoporous silica composites. Science 288 652-656... 

Inorganic Hybrid Materials Based on Mesoporous Silica Composites for Humidity Sensing Applications... 

Figure 20. Electro-osmotic drag coefficients of diverse membranes based on perfluorinated polymers (Dow - and Nafion/silica composites ) and polyarylenes (S—PEK/ PSU blends, ionically cross-linked S—PEK/PBP ), as a function of the solvent (water/methanol) volume fraction Xy (see text for references). Lines represent data for Nafion and S—PEK (given for comparison) for data points, see Figure 15. Dashed lines correspond to the maximum possible electro-osmotic drag coefficients for water and methanol, as indicated (see text).

Makote, R. D., Luo, H. M., Dai, S., Synthesis of ionic liquid and silica composites doped with dicyclohexyl-18-crown-6 for sequestration of metal ions. In Clean Solvents, ACS Symposium Series 819, 26-33, 2002. 

Fe203 and 55 weight % silica, as support, with 1% sodium silicate as a binder. In the preliminary work fly ash was considered as a support material but the maximum amount of iron oxide which could be incorporated with it was 25 weight % Based on this and the other criteria discussed above, the iron oxide-silica composition was found to be the most suitable sorbent for bulk H2S removal,... 

Figure 2.12. Photograph of silicon nanocluster-mesoporous silica composite film under UV irradiation at 77 K, showing bright visible nanosecond lifetime luminescence. Reproduced with permission from [90],...

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