Aqueous Deposition

Functional organosilanes can be applied to substrates directly from aqueous solutions, provided the silane compound is soluble is water. 

Dissolve an alkoxysilane in water at a concentration of 0.5-2.0 percent (v/v). If the compound is not very soluble in water, a nonionic detergent can be added to the solution at 0.1 percent to promote solubility. 

Contact the substrate with the silane solution from 2 minutes to as long as 1 hour, depending on the degree of organosilane polymer deposition desired on the surface. Optimization of the reaction time should be done to determine the best performance of the modified substrate in its intended application. 

Remove excess solution and cure at 110-120°C for 30 minutes to remove traces of water and form the siloxane bonds. 

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Aqueous deposition follows the same reactions as (a), More likely, however, a com-plexing agent, such as NH3, is used to reduce the reaction rate to improve film structure. This process can also be done electrolytically (with, e.g., CdS04 and Te02 as reactants) with underpotential deposition, the growth of one atomic layer at a time may be... 

A common method for the electrodeposition of Am is from isopropanol solutions containing small quantities of dilute acid stock solutions of Am ions. Aqueous deposition methods have also been employed, but the organic electrolyte medium is more advantageous in that it tends to produce more uniform coatings [151[. Zhi etal. prepared relatively thick targets of Am from a mixture of isopropanol and dilute (0.1 N) nitric acid stock solutions pf [152]. The electrolysis... 

A possible solution to these problems could be to replace the aqueous deposition media by room temperature ionic liquids (RTILs). These are defined as liquids consisting of molecular cations and anions that have a melting point below 100 °C. Due to the size of the molecular ions and the fact that the charge is delocalized through the molecule, these liquids have large electrochemical windows. Another potential benefit is that RTILs have high degradation temperatures and low vapor... 

Aqueous deposition methods are used to apply conversion coatings for decorative and protective reasons. These conversion coatings are formed by immersing the substrate metal in an aqueous solution of chromic acid, chromate or dichromate salts. For the deposition to occur activating ions such as sulfate, nitrate, chloride, or fluoride must be added. Then as hydrogen is generated by the attack of the activating ions some of the chromium ions are reduced to form a hydrated chromium chromate which is deposited on the substrate surface. 

Zhang H, Xu L, Yang F, Geng L (2010) The synthesis of polyacrylonitrile/carbon nanotube microspheres by aqueous deposition polymerization under ultrasonication. Carbon 48(3) 688-695. doi 10.1016/j.carbon.2009.10.013... 

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