Integrating Structural and Thermodynamic Mechanisms for Methanol Intercalated Kaolinite Nanoclay: Experiments and Density Functional Theory Simulation.

Abstract

Methanol intercalated kaolinite (Kaol) plays an important role in the intercalation, exfoliation, and organic modification of kaolinite nanoclay. However, the evolution of the layer structure of Kaol and its thermodynamic stability during the methanol intercalation process have not been clarified at the atomic level. Here, by combination of density functional theory (DFT) calculation and experimental characterizations, the interlayer bonding, structure evolution, and energetics from dimethyl sulfoxide (DMSO) intercalated Kaol to methanol intercalated Kaol were investigated. Partial methanol molecules entered the interlayers of Kaol to form some intermediate structures with the same d-spacing as that of DMSO intercalated Kaol. Different numbers of grafted methoxy and water molecules coexist together in the interlayer to form the final structures of methanol intercalated kaolinite (MeOm/nH2O/Kaol). The whole intercalation process is energy-consuming, and the presence of DMSO would affect the intercalation of methanol. Meanwhile, the formation energy from intermediate structures to final structures was found reduced under the participation of water.