Figure 3.

A plot of the contact angle ($\theta$) of the aqueous solution of DM on the PTFE (curves 1 and 1′), PE (curves 2 and 2′), PMMA (curves 3, 3′ and 3′′), nylon 6 (curves 4, 4′ and 4′′) and quartz (curves 5, 5′ and 5′′) against the logarithm of DM concentration ($C_S$). Curves 1–5—the measured $\theta$ values, curves 1′ and 2′—the $\theta$ values calculated from Equation (3), curves 3′, 4′ and 5′—the $\theta$ values calculated from Equation (5) and curves 3′′, 4′′ and 5′′—the $\theta$ values calculated from Equation (7).