Surface contact angle measurement

Being sensitive to the chemical composition of the outermost layers of the surface, contact angle measurement is widely used for characterizing polymer surfaces. Surface characterization for polymers using contact angle measurement and XPS will now be described in detail, as these are the most widely used methods. 

Table 1. Air/water/surface contact angles measured using the Wilhelmy plate method on surfaces incubated with deionised water for 10 minutes.

Effect of Plasma Treatment Time The water surface contact angle measurement and thermal conductivity measurement showed that plasma treatment of diamond nanoparticles with 1 1 ratio of O2/CH4 gave rise to the best surface wettability and the highest thermal conductivity of the resulting nanofluids. Using plasma gas mixture with a fixed O2/CH4 ratio of 1 1, therefore, effects of plasma treatment time on thermal conductivities of the resulting... 

Remarkably, an apparent mass loss is found for the second immersion cycle (Adv-fdc-2) reflective of a hydrophobic surface (0adv2 = 106°). Now, water-hydrogen bonding interactions are stronger than water-surface interactions and water resists wetting the surface. Contact angles measured by drop profile analysis are close to those observed for DCA. 

Singh, S. S., Pradip, and Rai, B. 2010. Wetting characteristics of mineral surfaces contact angle measurements through molecular dynamics simulations. In Proceeding of XXV International Mineral Processing Congress (IMPC 2010), AUSIMM, Brisbane, Australia, 2357. 

A. Horsthemke and J. J. Schroder, The wettability of industrial surfaces contact angle measurements and thermodynamic analysis, Chem. Eng. Process., 19 (1985), 277-285. 

Discuss the paradox in the wettability of a fractal surface (Eq. X-33). A true fractal surface is infinite in extent and a liquid of a finite contact angle will trap air at some length scale. How will this influence the contact angle measured for a fractal surface ... 

It should be noted that one may obtain an estimate for the surface energy of a solid from a single contact angle measurement by combining Eq. 9 or Eq. 11 with Eq. 3. One then has ... 

Section 4.1 briefly describes some of the commonly employed experimental tools and procedures. Chaudhury et al., Israelachvili et al. and Tirrell et al. employed contact mechanics based approach to estimate surface energies of different self-assembled monolayers and polymers. In these studies, the results of these measurements were compared to the results of contact angle measurements. These measurements are reviewed in Section 4.2. The JKR type measurements are discussed in Section 4.2.1, and the measurements done using the surface forces apparatus (SFA) are reviewed in Section 4.2.2. 

Surface energies determined by SFA and comparison to surface energies inferred from contact angle measurements (in mJ/m )... 

The surface energy of the solid can be obtained from equilibrium contact angle measurements of a series of test liquids on the solid surface, providing the relationship between ysi and the solid yg (in vacuo) and liquid yiv surface energies is known. The exact relationship is given by the Good and Girifalco equation [13,14] ... 

The surface forces apparatus (Section 2.3) enables the estimation of a surface energy term, Fq (Eq. 9), providing sufficiently smooth surfaces can be produced. In recent years Chaudhury, Pocius and colleagues have made a valuable contribution to the field of adhesion by developing the technique to study energies of adhesion and of surface energies of polymers [81-85]. These SFA results provide alternatives to values based on traditional destructive tests or contact angle measurements. 

The most widely used techniques for surface analysis are Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), Raman and infrared spectroscopy, and contact angle measurement. Some of these techniques have the ability to determine the composition of the outermost atomic layers, although each technique possesses its own special advantages and disadvantages. 

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