Can DLVO theory be applied to MOF in different dielectric solvents?

Abstract

ZIF-8 is widely used as a porous crystal material in the field of colloids. Its interfacial interactions are crucial to the performance of colloidal particles. In this paper, the Hamaker constant of ZIF-8 (3.45 × 10−20 J) was calculated for the first time by contact angle measurement parameters. The non-retarded Hamaker constant of ZIF-8 (4.66 × 10−21 J) was calculated using the Lifshitz's theory. Its dispersion in the dipolar (water) and monopolar (toluene) solvent systems was discussed using DLVO theory. The results showed that the energy potential barrier reached +183.9 KBT in the water system. However, the particles tended to be unstable in the toluene system, which did not correspond to the experimental phenomena we observed. Using the XDLVO theory, we took the Lewis acid-base fraction as an object of investigation, and the results showed that the hydrophobic attraction force between particles was 102 mJ/m2 in the dipolar solvent (water). In the monopolar system, the steric repulsion was linked to the Lewis acid-base fraction of the particles. XDLVO theory can better describe the dispersion of ZIF-8 particles in different solvents. In future work, it is necessary to consider the Lewis acid-base surface energy due to crystal defects, especially for the interfacial interaction between solvent and particles during the preparation of colloidal suspensions.