Hydrophobic silane solution

Liquid evaporation was employed for liquid pumping in Si-glass microchannels. With hydrophobic patterning at the outlet reservoir, the evaporation rate at the liquid meniscus was controlled to produce a flow rate of 5 nL/min. The hydro-phobic region was patterned by an A1 mask using a silane solution (FDTS) [146]. 

Catalysts such as amines or heat treatment helps accelerate the reaction since the reactivity of the above reaction is lower than the condensation reaction of silanol groups. Because there are few silanols available, the silane in this treatment method tends to be near a monomolecular equivalent A similar situation is also observed when a filler is heated in a silane solution of a hydrophobic solvent such as toluene. 

By silane treatment under proper experimental conditions, natural fibers, which are normally hydrophilic or hygroscopic, can be converted into hydrophobic fibers for nonpolar polymer matrices [28], reducing the water absorption rate. Silane treatment of natural fibers may more or less increase the thermal stability of natural fibers depending on the treatment conditions. Silane treatment normally does not damage the natural fibers because no fiber-damaging elements such as an acidic catalyst are present in the silane solution and high temperature treatment... 

The direction of electroosmotic flow and, therefore, the order of elution in CZE can be reversed. This is accomplished by adding an alkylammonium salt to the buffer solution. As shown in Figure 12.45, the positively charged end of the alkylammonium ion binds to the negatively charged silanate ions on the capillary s walls. The alkylammonium ion s tail is hydrophobic and associates with the tail of another alkylammonium ion. The result is a layer of positive charges to which anions in the buffer solution are attracted. The migration of these solvated anions toward... 

The silanization of the surface of a glass pipette may be necessary for different reasons [19]. If the pipette is to be filled with an aqueous solution, its outer wall should be made hydrophobic to prevent the formation of a thin aqueous film that may cause large deviations of the experimental diffusion-limiting current from the theory (see Section II.B). Experimental voltammograms were found to quantitatively agree with the theory after the aqueous layer was eliminated by silanizing the outer pipette wall. 

The outer wall of a pipette can be silanized by immersing the pipette into a solution of trimethylchlorosilane. For experiments with water-filled pipettes, it is crucial to avoid silanization of the inner wall because the outer organic solvent is drawn inside a pipette if its inner surface is hydrophobic. Thus the flow of argon should pass through the pipette from the back while its tip is immersed in a solution of trimethylchlorosilane. 

The hydrophilic SiO substrate)static water contact angle 0=3O°) was prepared by vapor-deposited SiO onto a Formvar substrate[4], with which an electron microscope grid(200-mesh) was covered. The relatively hydrophobic siliconized substrate(0=9O°) was also prepared by surface siliconized treatment a collodion-covered electron microscope grid was dipped into an aqueous solution of silane coupling agent. 

It is also worthwhile to outline at this place the immobilization procedure that was used for the preparation of type I CSPs A bifunctional linker with a terminal isocyanate on one side and a triethoxysilyl group on the other end (3-isocyanatopropyl triethoxysilane) was reacted with the native cinchona alkaloids quinine and quinidine and subsequently the resultant carbamate derivative in a second step with silica [30], Remaining silanols have been capped with silane reagents, yet, are less detrimental for acidic solutes because of the repulsive nature of such electrostatic interactions. CSPs prepared in such a way lack the hydrophobic basic layer of the thiol-silica-based CSPs mentioned earlier, which may be advantageous for the separation of certain analytes. 

Overloading effects seem even more complex at intermediate pH because silan-ols are now partially ionized and involved in the retention of bases. As mentioned previously, the overload of now-ionized silanols could at least be part of the cause of tailing peaks, even when very small amounts of ionized base are used [18,24]. However, it has been observed that as solute mass increases in experiments at pH 7, column efficiency may improve from an initially low value to a maximum, afterward declining in the usual way [33]. This observation could be due to the blocking or saffiration of ionized silanols by a portion of the sample, such that the rest interacts mainly by hydrophobic processes, resulting in better efficiency. At higher pH still, the solute should not be ionized if appreciably above its p a and therefore should... 

Adsorbed films of ethykriethoxysilane and vinyltriethoxy-silane were formed on silica and alumina by retraction from hydrocarbon solution and their wettabilities and water-stabilities determined. The vinyltriethoxysilane films were generally more oleophobic, more hydrophobic and more resistant to contact with water than the films formed by the ethyl analog. Neither adsorbate formed stable films on a-alumina. The addition of low molecular weight organic acids or bases to the adsorbate solution resulted in both the ethyl and vinyl compound forming hydrophobic and water-stable films on silica and ot-alumina. Films of p-chloro-phenyl-ft-ethyltrichloro, -trimethoxy, and -triethoxysilane were also studied and found to be water-stable and to have wettabilities characteristic of a surface comprised of closely-spaced p-chlorophenyl groups. 

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