Contact angle adsorption and

There is no reason why the distortion parameter should not contain an entropy as well as an energy component, and one may therefore write 0 = 0q-sT. The entropy of adsorption, relative to bulk liquid, becomes A5fi = sexp(-ca). A critical temperature is now implied, Tc = 0o/s, at which the contact angle goes to zero [151]. For example, Tc was calculated to be 174°C by fitting adsorption and contact angle data for the -octane-PTFE system. 

Adsorption and Contact Angle Behavior on Flat Polymer Surfaces Potential - Distortion Model... 

Table I gives the fitting parameters for Equation 6, the values being chosen with the constraint that they also give the experimentally observed contact angle. The interaction and distortion energies, Eq and B, correspond to only a few hundred cal mole for the process (bulk water) - (adsorbed film), and it is important to realize that relatively minor energy effects are deteinnlnatlve of the adsorption and contact angle behavior. The energy relaxation distance, 1/S, is much larger for water adsorbed on PTFE than on PE, while the distortion relaxation distance, 1/8, is smaller. The picture is that water on PTFE is more weakly held than on PE, but more distorted in structure relative to bulk water.

Data for copper coated with a stearic acid monolayer are included in the Table, in illustration of another type of hydrocarbon surface—one now rich in CH3 groups. As might be expected, the adsorption and contact angle behavior resembles more that for PE than for PTFE. 

Table I. Adsorption and Contact Angle Behavior of Water on...

Tadros ME, Hu P, Adamson AW (1974) Adsorption and contact angle studies. 1. Water and smooth carbon, linear polyethylene, and stearic add-coated copper. J CoU Interf, Sci 49 184-195 Tadros TE, (ed) (2011) Self-organized surfactant structures. Wiley-VCH Verlag, Germany, pp 270 Tarasevich Yul (2008) Energetics of the interaction of water and other liquids with bthe surface of hydrophilic and hydrophobic sorbents according to data on the heats of wetting. Theor Exptl Chem 44 1-23... 

Figure 1 Adsorption and contact angles of fat crystals at the interface of an oil-in-water. (Adapted from Ref. 30.)...

The adsorption of gas onto a solid surface can also be used to estimate surface energy. Both inverse gas chromatography (IGC) and isotherm measurement using the BET method [19] have been used. Further discussion and detailed references are given by Lucic et al. [20] who compare the application of IGC, BET and contact angle methods for characterising the surface energies of stearate-coated calcium carbonate fillers. 

The adsorption of alkyl and aryl isocyanides on Au film [26, 32, 33], powder [36, 37] and nanoparticles [39, 41, 42] has been studied using several different techniques IR methods (RAIR, ATR-IR, DRIFT), Raman methods (SERS), X-ray methods (NEXAFS), ellipsometry (OE, SWE) and contact angle measurements (ACA). The gold surface is not oxidized under normal conditions consequently, the experiments were performed in air at room temperature. The gold film was obtained by physical vapor deposition of 100-200 nm of gold on different substrates glass [28, 33], mica [33], silicon [25, 27, 31, 32], ZnSe crystal [26]. A... 

Whatever the composition of the Ni-Si alloy, the adsorption of Ni, r, at the alloy/SiC interface is positive, corresponding to YNi/XNi values of 1.5 to 2. Enrichment of the interface in Ni indicates that interactions between Ni and SiC at the interface are stronger than those between Si and SiC. The work of adhesion of pure Ni on SiC in metastable equilibrium (i.e., for a supposed non-reactive Ni/SiC system), evaluated in Appendix I, is W 1 = 3.17 J/m2. This value is reported in Figure 7.6 along with the corresponding values of work of immersion and contact angle. 

Adsorption of bases (n-bu-tylamine) in aprotic solvents using Hammett or arylmeth-anol indicators Wetting with liquids Microscopy Total content of surface acid sites, acidity distribution Surface energy, surface wettability, and contact angle 25... 

FIGURE 39.2 Correlation of adsorption density, contact angle, flotation response and zeta potential for quartz as a function of dodecylammonium acetate concentration at pH 6 to 7, 20 to 25°C [5]. 

Figure 10.23. Adsorption isotherm (squares), zeta potential (triangles), and contact angle (circles) data of silica surfaces, obtained in O.lAf NaCl at pH 4.0 as a function of the solution C12TAB concentration (after ref. (10)). ( Reproduced with permission from Langmuir, 2000, 16, 7255-7262, Copyright (2000) American Chemical Society )...

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