Organically modified silanes

Markowitz et al. developed a different approach, again in an attempt to overcome some of the inherent difficulties that arise when imprinted bulk materials are used as catalysts [82], Here, the authors used a template-directed method to imprint an a-chymotrypsin TSA at the surface of silica nanoparticles, prepared with a number of organically modified silanes as functional monomers. Silica particle formation was performed in a microemulsion, where a mixture of a non-ionic surfactant and... 

It is known that the advantages of imprinted ormosils (organically modified silanes) over acrylic-based MIPs are their chemical stability, the high thermal stability of sol-gel materials, synthesis in mild temperature conditions, optical transparency, photo-, electro- and chemical stability, all properties that made these materials ideal for use in optical sensing approaches, particularly in aqueous samples.48 50 Although... 

Recently, Reetz and others have published a number of studies showing that adding organically modified silanes (precursors), such as methyltrimethoxysilane or poly (dimethylsiloxane), to tetraethoxysilane (TEOS) during hydrolysis can produce a protein-doped organicinorganic hybrid material that is hydrophobic [1-7]. Systems already tested... 

Another issue posed by silica capsules has to do with the brittle nature of the glass shell that often requires (see the following text for encapsulated waxes) the use of organically modified silanes in the precursor mixture along or in place of TEOS. 

Que W., Zhou Y., Lam Y.L., Pita K., Chan Y.C., Kam C.H. Luminescence properties from erbium oxide nanocrystals dispersed in titania/organically modified silane composite sol-gel thin films. Appl. Phys. A 2001b 73 209-213... 

Que et al. have reported the fabrication of optical channel wavegides and gratings made from composites of titania and organically modified silane (Que et al., 2002). The composite is prepared using 3-glycidoxypropyltrimethoxysilane and titanium tetrapropoxide stabilized with acetylacetone as precursors. Dense and porosity-free waveguide film is obtained... 

In monolith febrication it is required to take into account the influence of the precursor gradient chemical composition on the sol-gel process. Parameters that affect the process are metal alkoxide precursor types, pH effect - type of catalyst used, H2O Si molar ratio (/ ), steric effect of precursor ligand groups, and functionality of organically modified silanes (ORMOSIL). 

The functionality of organically modified silanes influences the fabrication of the monolith in several ways. As already mentioned in Section (10.2.3.4), the size of the organic ligand can induce steric effects and slower reaction time. In addition, less polymerized silanol groups (due to the functional ligand groups) ako lead to slower reaction time. When the reaction time is slower, a monolith can be fabricated more easily. 

Lavrencic Stangar, U., Orel, B., Vince, J., Jovanovski, V., Spreizer, H., Surca Vuk, A. Hocevar, S. J. (2005). Silicotungstic acid/organically modified silane proton-conducting memhrmes. Journal of Solid State Electrochemistry, 9, 106-113. 

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