Surface Potential Dependence of the Hamaker Constant

Hamaker constant is a key parameter in the study of particle interactions of materials. Even though there are quite a few methods for measuring the Hamaker constant, the current experimental results showed that the obtained Hamaker constants from different methods for the same material usually had considerable variations. In this paper, a new method for determination of the Hamaker constant was suggested: the Hamaker constant can be easily measured through determination of the swelling pressure of the material in aqueous solution. In this paper, the Hamaker constants of 36 different montmorillonites with different surface potentials were obtained by the method. The results showed that the Hamaker constant of montmorillonite was surface potential dependent. At values of the surface potential larger than −267 mV, the values of the Hamaker constant increased with an increase of the surface potential; nevertheless, at surface potentials lower than −267 mV, the Hamaker constant appeared to decrease with an increase of the surface potential.