Contact angles, advanced chemically

Chemical potential Activity coefficient Contact angle Advancing contact angle Receding contact angle Density... 

One other cause of hysteresis remains to be mentioned. As was pointed out earlier (p. 177) the contact angle may be different as the mercury is advancing over or receding from a solid surface, and it depends also on the chemical and physical state of the surface the mercury may even react with the surface layer of the solid to form an amalgam. A change in 9 of only a few degrees has a significant effect on the calculated value of pore radius (cf. Table 3.15). 

Sharpe, L.H. and Schonhom, H. In Fowkes, F.M. (Ed.), Contact Angle, Wettability and Adhesion, Advances in Chemistry, Series 43. American Chemical Society, Washington, DC, 1964, p. 189. 

Huntsberger, J. R. In Contact Angle, Wettability, and Adhesion Fowkes, F. M., Ed. Advances in Chemistry Series No. 43 American Chemical Society Washington,D. C., 1964 Chapter 7. 

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 surface wettability by water drops has been clearly linked with the concentration of chemically bound nitrogen in the surface. Conversely, measurements of advancing and receding contact angles for water can provide information regarding surface composition. On the other hand, there appears to be little or no direct correlation between water wettability and adhesive strength of evaporated aluminum films. Substantial improvement in adhesion of Ai to many polymers can be achieved by 02 plasma treatment of the polymer surface before metallization. Other workers have shown this to result in chemical linkages between the metal and polymer surface moieties. 

The chemical structure and composition of films deposited onto the Al substrates was determined by X-ray photoelectron spectroscopy (XPS) using a Perkin Elmer PHI 548 instrument. Measurement of advancing and receding water contact angles (aa and or, to 3°) were carried out by the sessile drop technique, using a Rame Hart contact angle goniometer (10 ). 

---