Porous organically modified

Chemistry and Properties of Porous, Organically Modified Silica... 

Sol-gel techniques were used to prepare porous, organically modified silica materials. The introduction of organic groupings was carried out with alkoxysilanes as precursors methyl and propyl amino groups were used. The results show that high-porosity materials can be synthesized the microstructure strongly depends on reaction conditions such as composition, solvent, catalyst type, and concentration. Microstructure tailoring affects mechanical as well as adsorption properties, and custom-made materials such as abrasives and adsorbents with special properties were synthesized. 

Organically modified porous silicates have been prepared under acidic conditions, by direct reaction of a mixture of phenyltriethoxysilane (PTES) and tetraethoxysilane (TEOS), and an aqueous solution of cetyltrimethylammonium bromide (CTAB). For a 1 4 molar ratio between PTES and TEOS, the hexagonal (2d, p6m) phase, but also a cubic phase analogous to the already reported SBA-1 phase (Pm3n), can be prepared. The surfactant can then be efficiently removed by calcination at 350°C, leading to phenyl-functionalized microporous silicates with two types of architecture. The influence of several parameters (PTES/TEOS ratio ethanol content) that affect the organization of the samples, will be discussed. 

Slow rerarrangement of molecules can be due to long diffusional paths, constricted diffusion channels in a solid matrix or diffusion through a dense or highly viscous material. Diffusion of KCl and chlorinated benzenes through immobile fluid for the unmodified versus organic-modified porous... 

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