Sol silica coatings

ALUMDIUMCOMPOUNDS - ALUMINIUMOXIDE(ALUMINA) - HYDRATED] (Vol 2) Alumina-coated silica sols... 

PercoU is a polyvinylpyrrolidone-coated silica sol with very low osmolarity. For cell separations therefore the osmolarity is adjusted to isotonic conditions by mixing 9 vol. Percoll stock suspension with 1vol. of 2.5 M sucrose, 1.5 M sodium chloride, or tenfold concentrated cell culture medium (e.g., 10 x RPMl). 

The industrial development of silica sol manufacturing methods is reviewed. Primary attention is focused on the preparation of monodispersed sols from water glass by the ion-exchange method. Details are given for variations of manufacturing process and for the characteristics of both the processes and sols obtained. Furthermore, the following surface modifications of particles are demonstrated silica sols stabilized with ammonia, amine, and quaternary ammonium hydroxide aluminum-modified or cation-coated silica sol and lithium silicate. Finally, future trends in silica sol manufacturing are discussed from the viewpoint of not only raw materials and improvement of the procedures but also the function of the silica sols and their particle shape. 

Figure 7. Flow chart of production of cation-coated silica sol.

The catalytic performance of Pt on silica, applied by direct impregnation or using Pt-coated silica sol, is as high as that of Pt on alumina, applied by adsorption or direct impregnation. 

Patents have been issued covering spraying the wax pattern with silica sol and acid (519), coating with a concentrated acidic alcohol-water sol (520). using a dye in the coating slurry that indicates when the coating has dried (521), and use of alumina-coated silica sol (522). 

Wear resistant coatings silica sol gd reinforced with carbon nanotubes. Thin Solid Films, 519 (22), 7904 7910. 

American scientists prepared the organo-silica sol-gel membranes60 and demonstrated in a single layer format for pH measurement and multiple-layer format for both C02 and NH3. The sensors used a hydroxypyrenetrisulfonic acid (HPTS) as the indicator immobilizes in a base-catalyzed sol-gel containing poly(dimethyl)siloxane, aminopropyl-triethoxysilane (APTES) and tetraethylorthosilicate (TEOS). This indicator gel was over coated with a hydrophobic sol-gel to reduce cross reactivity to pH when either carbon dioxide or ammonia were examined. 

The introduction of 2-[4-(dimethylamino)phenylazo]benzoic acid into a silica sol allows the preparation of pH-sensitive doped coatings upon glass substrates. The behavior of this system was evaluated as the function of pH changes in liquid and gas media68. Optical absorption and sensitivity against pH were monitored by Vis spectroscopy. Chemical and mechanical stability tests carried out with coatings demonstrated that they were resistant enough to be use in sensor devices for pH measurements in laboratories. 

A thin film dissolved oxygen sensor was fabricated by entrapping erythrosin B in a sol-gel matrix95. The silica sol-gel doped with the dye was deposited onto the cleaned glass slides by the spin-coating method. The sensor was linear in the most useful range of dissolved oxygen concentrations, up to 9.1 mg l 1 concentration obtained in air saturated water at 20 °C. 

B. Mahltig and H. Bottcher, Modified Silica Sol Coatings for Water-Repellent Textiles, J. Sol-Gel Sci. Technol., 2003, 27, 43. 

Fig. 15. Electrochromatograms obtained in columns coated with sol-gel composites (A) TEOS and (B) C8-TEOS/TEOS. (Reprinted with permission from [80]. Copyright 1999 American Chemical Society). Separation conditions fused silica capillary, 12 pm i.d., 60 cm total length, 40 cm active length, mobile phase 60/40 methanol/1 mmol/1 phosphate buffer, voltage 30 kV, electrokinetic injection 5 s at 6 kV, UV detection at 214 nm. Peaks toluene (1), naphthalene (2), and biphenyl (3)...

Antireflective (AR) coatings are required on optics to reduce the reflective surface losses. Vitreous silica coatings in the form of porous or multilayer films are used extensively in this application. Antireflective coatings have been developed which employ colloidal fused silica sol—gel particles made from organometallic materials (253). 

Sol-gel coatings -silica gels as [SILICA - AMORPHOUS SILICA] (Vol 21)... 

Ascorbic acid Mediated oxidation at a silica sol-gel glass coated ferricyanide-doped Tosflex-modified SPCE FIA +0.3 V 46 nM to 300 nM 46 nM Zen et al. [66]... 

Control of pore sizes of known catalysts like zeolites has been known for some time although the use of chemical vapor deposition (CVD) of organosilanes to control pore sizes has been the focus of recent research.7 Other catalysts like silica have been treated with methods like CVD and sol-gel in order to deposit thin films. Monolayer coatings of titanium oxide prepared by sol-gel methods have been recently used to coat silica and such films are active in alcohol dehydrogenation reactions.8... 

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