Cassie contact angle

C Cassie contact angle on a chemically heterogeneous surface... 

Why do you think the Cassie equation Eq. X-27 might work better than Eq. X-28 for predicting the contact angle as a function of surface polarity ... 

Fig. 9.10 Comparison of the formation and wetting behavior of the aliphatic HUT/DDT (a,c,e) and the aromatic HMB/MMB (b,d,f) mixed monolayer system on Au(lll). (a,b) Composition of the solution and surface composition of the resulting SAM. (c,d) Plot of the cos 6>= (7sv-7si)/7iv) of the advancing (and additionally in d) receding) water contact angle as a function of the surface OH concentration. The straight line represents the Cassie equation [104], in c) the grey line is calculated after the equation from Israelachvili [105] describing the contact angle on heterogeneous surfaces. (e,f)...

Another modification was performed by Cassie considering the surface heterogeneity [33]. If two phases (phases 1 and 2) with different surface energies exists on the identical surface, the apparent contact angle is described as follows ... 

The second set of equations come from Cassie and Baxter - l. Cassle eonsidered a smooth, but chemically patchwlse heterogeneous solid surface, composed of fractions and with ideeil contact angles and a, respectively. For the average he wrote the Cassie equatiorfi ... 

In 1944, Cassie and Baxter derived an equation describing contact angle hysteresis for composite smooth solid surfaces with varying degrees of heterogeneity ... 

When air pockets are present on a rough surface, the Cassie-Baxter equation can also be applied to the contact angle estimate of a water drop on such a surface. Since the contact angle of water in air is equal to 180°, by taking 02 = 180°, which corresponds to (cos ft = -1), Equation (676) then becomes... 

The modified Cassie-Baxter equation was successfully used to interpret some of the contact angle data reported for heterogeneous surfaces. 

The effect of roughness on the wettability of an idealized sinusoidal surface has been studied with a digital computer. The equations of Wenzel and of Cassie and Baxter are discussed in relation to the model. The heights of the energy barriers between metastable states of a drop are seen to be of utmost importance in determining the magnitude of contact angle hysteresis. 

Maximum and minimum possible angles Most probable contact angles, 0 Lower. Calculated from Wenzel s equation Upper. Calculated from Cassie and Baxter s equation Possible curve of receding angles Possible curve of advancing angles... 

Fig. 6. Effect of roughness on contact angle A, maximum and minimum angle B, Wenzel equation (lower) and Cassie and Baxter equation (upper) 6, and 6 possible receding and advancing angles (Ref. )...

Contact angles for water on partially methylated quartz plates were found to be in close agreement with the Cassie equation by R. Crawford, L, K. Koopel, and J. Ralston Colloids and Surfaces, in press (1987)... 

Fig. 9. Effect of surface chemical heterogeneity (0, = 120°, 0j = 0°) on contact angle hysteresis A, Cassie and Baxter angle, curves 1-4 represent effect of assumed energy barriers (Ref.

---