Fast sol-gel process

The concept of the fast sol-gel process is to complete the reaction of all the precursors and evacuation of the unnecessary products (alcohol and water)... 

Gvishi, R., Englander, A., and Peleg, G. (2008) Multi-parameter evaluation of fast sol-gel process by terahertz measurements. /. Sol-Gel Sci TechnoL,... 

Fast Sol-Gel Reactions with Monomers other than MTMS. An intriguing question derived from the MTMS fast sol-gel process is whether the principle of "three hydrolyzable substituents applies only to a pure alkyl-trialkoxy monomer or perhaps it can be applied also to a mixture of tetra- and di- alkoxysilanes and may be even to multi-componet mixtures. A series of experiments was carried out with binary mixtures of tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DMDMS), employing exactly the MTMS reaction procedure and casting process. The molar ratio of water to siloxane was kept at 1.5 (substoichiometric, in most cases). The results of these experiments are collected in Table IV. 

Donor-Acceptor type molecules such as p-nitroaniline (PNA) and diamino-diphenylsulfone (DDS) are embodied in the PMSO glasses by the same fast sol-gel process as laser dyes. Higher loadings (10-15%) of these chromophores could be... 

Solar energy, 6, 488 surface modified electrodes, 6, 30 Sol-Gel process fast reactor fuel, 6, 924 Solid state reactions, 1, 463-471 fraction of reaction, 1, 464 geometric, 1, 464 growth, 1, 464 nucleation, 1, 464 rate laws, 1,464 Solochrome black T metallochromic indicators, 1,555 Solubility... 

Either particulate sol or polymeric sol has been used for thin film coatings. The polymeric sol was fabricated by partial hydrolysis of corresponding metal alkoxide. If the rate of hydrolysis or condensation is very fast, then some kinds of organic acids, beta-dicarbonyls, and alkanolamines have been used as chelating agent in sol-gel processes to control the extent and direction of the hydrolysis-condensation reaction by forming a strong complex with alkoxide. [2]. 

For example, the sol-gel process, which grew so fast in the late 1950s and the 1960s and continues to expand and generate new approaches and materials, began not by mere coincidence about 1 year after the publication of Iler s book. The term sol-gel was heard for the first time around 1956. It is believed to have been coined by researchers at the Oakridge National Laboratories (ORNL) (P.H. Emmett, personal communication, 1959). 

A particular versatile method to prepare stable templates and casts is the sol-gel process. In this process an inorganic ester is hydrolyzed to form the free acid. Afterwards the acid condenses to form a three-dimensional network or gel (Scheme 1). Usually it is desirable to have a fast hydrolysis which has a large reaction constant ki followed by a slower polycondensation with a smaller constant A 2- This allows one to homogenize the solution and cast it into the desired form before it solidifies. The values of ki and /C2 can in many cases be adjusted by changing pH and temperature of the solution. 

Pietrass et al also used xenon NMR to examine the porosity of three me-soporous silica materials that were synthesized by sol-gel processing. Xenon did not penetrate the pores of a sample of largely disordered silica. The other two samples showed more typical xenon adsorption and chemical shift behavior. Results from variable temperature and Ti experiments indicated that xenon had a stronger interaction with the surface of smaller pores and that it was in fast exchange with the gas phase. 

The effects of different synthesis parameters on the properties of zirconia aerogels prepared by sol-gel process have been investigated by many research groups. In fact, taking into account that the hydrolysis of zirconium alkoxides is very fast, it has been noted that the rate of the condensation process can be influenced by the concentration of an acid catalyst leading to zirconia aerogels with different textural properties. The amount of added water... 

A simple method was developed (Gao R. et al., 2010) to synthesize core-shell molecularly imprinted polymers for the extraction of tridosan with fast kinetics, high capacity and favorable selectivity by combining a surface molecular impainting technique with a sol-gel process based on carbon nanotubes coated with siUca... 

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