Contact angle measurement wetting force

Figure 2 is a representation of the force balance on a Wilhelmy plate that has gone through one phase and has been wetted by a second phase. The three interfacial tensions are related to the contact angle (measured through phase 2) by the familiar Young equation... 

The second strand of recent evidence for slip at the wall is due to Zhu and Granick [7][8]. These authors employed a force balance apparatus to study the hydrodynamic squeeze force between a pair of crossed mica cylinders lubricated by both tetradecane and water. As with the alumina stufaces used by Pit et al. above, the mica surfaces were chemically modified, either by grafting on them a lyophobic monolayer of long chain octadecyl-triethoxysiloxane (OTE) or by adding a surfactant (1-hexadecylamine) to the tetradecane solvent. Contact angle measurements showed that these treatments converted the normally fully-wetted mica surface to one only partially wetted by both test liquids. 

Kennedy et al. reported [79,80] that the amphiphilic materials consisting of hydrophic polyisobutylene (PIB) and hydrophilic poly(, V-dimethylac-rylamide) showed lower human blood monocyte adhesion than that of PIB and hydrophilic poly(2-hydroxyethyl methacrylate), for which the weight fractions between hydrophobic and hydrophilic components were identical. However, the amounts of various adsorbed proteins onto these samples were similar [79,80]. The relation between protein adsorption and cell adhesion has not yet been elucidated. The surface characterization methods that we employ were contact angle measurements, XPS, and SEM. There must be some structural differences among these samples of PAS that we could not detect using the aforementioned apparatus. Further studies on the surface structure of PAS by TEM and atomic force microscopy (AFM) in dry and wet conditions are now in progress. 

Table 5.1 Contact angle measurement data and wetting and adhesion force data for water on...

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