Contact angle data

Ruch and Bartell [84], studying the aqueous decylamine-platinum system, combined direct estimates of the adsorption at the platinum-solution interface with contact angle data and the Young equation to determine a solid-vapor interfacial energy change of up to 40 ergs/cm due to decylamine adsorption. Healy (85) discusses an adsorption model for the contact angle in surfactant solutions and these aspects are discussed further in Ref. 86. 

A major contribution to the rational organization of contact angle data was made by Zisman and co-workers. They observed that cos 6 (advancing angle) is usually a monotonic function of 7l for a homologous series of liquids. The proposed function was... 

Since both sides of Eq. X-39 can be determined experimentally, from heat of immersion measurements on the one hand and contact angle data, on the other hand, a test of the thermodynamic status of Young s equation is possible. A comparison of calorimetric data for n-alkanes [18] with contact angle data [95] is shown in Fig. X-11. The agreement is certainly encouraging. 

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. 

Summary of methods for estimating surface energy from the contact angle data... 

The change in surface wettability (measured by the contact angle) with concentration for the three surfactants is plotted in Fig. 2.54 (Zhang and Manglik 2005). The contact angle reaches a lower plateau around the CMC where bilayers start to form on the surface. Wettability of non-ionic surfactants in aqueous solutions shows that the contact angle data attains a constant value much below CMC. Direct interactions of their polar chain are generally weak in non-ionics, and it is possible for them to build and rebuild adsorption layers below CMC. The reduced contact an-... 

Fig. 17 Dry thickness of poly(acryl amide) (PAAm), /z, (closed symbols) and contact angle of DI water, 6>diw> (open symbols) as a function of the position on the substrate for samples prepared on substrates containing the initiator gradients made of CMPEiPO mixtures (w/w) 1 1 a ( , ) and b 1 5 (A, A). The contact angle data have an error better than 1.5 deg and 1 mm on the vertical and horizontal scales, respectively. (Reproduced with permission from [76])...

Fig. 4 Water contact angle data (a) and surface energy data (b) from a surface energy library produced through the graded UV-ozonolysis of an ODS self-assembled monolayer on sihcon. (Reproduced with permission from [17])...

Fig. 12 Surface expression of block segments in block copolymer gradient libraries after treatment to two solvents. See text for details a illustration of surface expression of PnBMA black) and PDMAEMA blue) block copolymer brush segments after water and hexane treatments b water contact angle data from three PnBMA-b-PDMAEMA block copolymer gradient libraries after hexane filled symbols) and water open symbols) treatments. (Derived from [58] with permission)...

Contact Angle Data of Different Liquid-Solid Systems... 

Although the extent of reaction cannot be quantitatively estimated from the contact angle data, it provides a number of information on the physico-chemical state of the surface. For instance, the remarkable difference in the advancing and receding contact angle observed in Figures 3 and 4 implies that the surface structure may be considerably different from... 

The water contact angle data for VTES on air-dried silica (Figure 6B) indicate a gradual increase in 0H2o with time. The rate of increase and the ultimate value of 0H2o after 20 hours adsorption time were both greater at the higher concentrations. 

Figure 1.7. Dependence of contact angle on the metal droplet radius for Pb on vitreous carbon at a temperature close to the melting point of Pb. The horizontal line identifies the macroscopic contact angle. Data from work reported in (Chizhik et al. 1985).

For other metal-like carbides (TiC, ZrC, VC, T aC), an estimation of the minimum value of ffsv can be made using contact angle data of ferrous metals (see Table 7.12) and assuming that ferrous metal/metallic carbide systems is close to 500 mJ / m2, so a more plausible value for [Pg.171]

Figure5.8. Contact angle data for Ag-28 wt.% Cu and Ag-16 wt.%Cu-14wt.% Pd on A1SI321 steel in a vacuum of 2 x 10-4 Pa during a temperature rise with a heating rate of 5°C/min. The vertical bars identify melting temperatures. From (McGurran and Nicholas 1985).

Table 6.1. Contact angle data for some pure metals on monocrystalline AI2O3 obtained under high vacuum or reducing gas environment. From (Chatain et al. 1986) except for Au at 1365K. (Chabert 1992), Fe (Nakashima et al. 1992), Ni (Nogi et al. 1992b) and Sb (Harter 1990).

Carbon Oxygen (C/O) Ratios, as determined by X-ray photoelectron spectroscopy and contact angle data for polystyrene. 

While contact angle data show the influence of water immersion clearly, XPS analysis of atomic ratio for O/C measured at the normally employed take-off angle... 

The general relationship cos 0o,a < cos 0s < cos 0o,r was extended to a direct correlation proposed by Uyama et al. [12]. The correlation states that the mean of cos 0D a and cos equals cos 0s. Application of this correlation to dynamic and static contact angle data of untreated and plasma-treated polymers was found to fit well as seen in Figure 26.20. 

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