A simple experimental way of measuring the Hamaker constant A(11) of divided solids by immersion calorimetry in apolar liquids

Recent progress in interpretation of immersion calorimetry has shown the li nk between the immersion enthalpy (Delta(imm) H) value in apolar liquid and the Lifshitz-van der Waals contribution to surface energy (gamma(S)(LW)) o f divided solids. In this work we show that a simple relationship can be es tablished between the Hamaker constant (A(11)) of a solid and its immersion enthalpy in a pure apolar solvent, The results are satisfying compared to those already available in the scientific literature. The main interest of this method is the measurement of the Hamaker constants of solids for which contact angle measurements are impossible to carry out and for those for w hich the complexity of the solid structure hampers the ab initio calculatio n. Values are given for some clay minerals. (C) 2000 Academic Press.