Substrate surface tension, effect

Leenars has shown both from theoretical considerations and experimental measurements that the passage of a liquid-gas phase boundary along the substrate may result in particle removal. It is shown that since both Ep/g (Equation (9.2)) and (Equation (9.5)) are both proportional to R, the surface tension effects can be utilized to clean particles of all sizes. Theoretical considerations are described in Reference (11). By adopting a suitable combination of the cleaning liquid, particle, and surface properties, adhesion forces can be overcome by surface-tension-related forces — the adhesion of the particles to the liquid-gas phase boundary is stronger than their adherence to the substrate. This leads to subsequent removal of the particle into the moving liquid. McConnell has shown that isopropyl alcohol (IPA) can be used to achieve this type of... 

The effect of the surface tension on the quality of coatings is studied in [200]. When a coating is applied to a curved substrate, surface tension gradients are produced in the comers as result of diffusion of water-soluble surfactants. Hence, the coating thickness reduces at the circumference and increases in the centre. It is shown that an optimum surfactant concentration as well as an optimum method of coating application are important. 

Surface tension effects caused by the existence of preferential substrate sites... 

Absorption and wetting. Generally, it is necessary for the adhesive resin to wet the substrate surfaces. The surface energy of the composite substrate must be greater than the surface energy or surface tension of the resin in order for effective wetting to occur. 

Solvents influence rate as well as selectivity. The effect on rate can be very great, and a number of factors contribute to it. In closely related solvents, the rate may be directly proportional to the solubility of hydrogen in the solvent, as was shown to be the case for the hydrogenation of cyclohexene over platinum-on-alumina in cyclohexane, methylcyclohexane, and octane 48). Solvents can compete for catalyst sites with the reacting substrates, change viscosity and surface tension (108), and alter hydrogen availability at the catalyst surface. 

A different aspect of preparation of an organized nanoparticles on a fluid is called as the rheotaxy technique. It is a well-established one to fabricate a well-crystallized film. Mobility of the atoms on the surface of the liquid substrate favors the aggregation of atoms in the growing films (41). In order to avoid a drawback of the rheotaxy, i.e., the negative effect of high surface tension of the substrate, a modification has been made by Romeo et al. (42,43), where they used substrates of elevated temperature close to but below their melting points. They prepared, e.g., ZnS Mn thin films on some low-melting metals such as Pb, Bi or Bi-Sb alloy. 

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