Application of thermal analysis for the characterisation of intercalated and grafted organo-kaolinite nanohybrid materials

Nanohybrid materials resulting from the intercalation of ionic liquids or from the grafting of aminoalcohols into the interlayer space of kaolinite pre-intercalated with dimethyl sulfoxide (DMSO), were successfully synthesized. Thermal analysis (TG and DTA) data, coupled with X-ray diffraction (XRD) data, and ¹³C MAS-NMR spectroscopic analysis, as well as with hydrolysis reactions, were used for qualitative and quantitative characterisations. In the case of intercalated nanohybrid materials obtained by insertion of ionic liquids and of ethanolamine into the interlayer spaces of kaolinite upon displacement of DMSO, no major changes in the dehydroxylation temperature of the layer sheets could be observed. The stoichiometry of the intercalated organo-kaolinite materials was obtained from several independent measurements (TG, CHN) and theoretical calculation (THM). They were in good agreement. Grafted nanohybrid materials resulting from the formation of a covalent bond between the hydroxyl groups of diethanolamine and triethanolamine and the internal surfaces aluminol groups of kaolinite exhibited a significantly lower dehydroxylation temperature. A combined approach of hydrolysis reactions and TG analysis allows an unambiguous distinction between grafted and intercalated organo-kaolinite nanohybrid materials.