One-pot exfoliation of kaolinite by solvothermal cointercalation

Abstract A one-pot solvothermal synthesis procedure of kaolinite-cetyltrimethylammonium chloride complex directly from kaolinite-urea precursor to produce kaolinite nanoscrolls is reported. Compared to the commonly applied solution/stirring method, the applied solvothermal synthesis is simple, convenient and effective, requiring an order of magnitude less time and reagent volume. The type of precursor, as well as the reaction time and temperature significantly affect the exfoliation rate of kaolinite. In addition, a strong correlation is demonstrated between the effectiveness of exfoliation and the interaction between the guest molecules and the octahedral sheets of kaolinite. The present findings reveal that the eco-friend kaolinite-urea precursor is favorable for direct intercalation of cetyltrimethylammonium chloride from methanol solution at 100 °C (and at equilibrium vapor pressure of methanol), and that the formed kaolinite-cetyltrimethylammonium chloride complex can easily transform into kaolinite nanoscrolls. This conceptually new method utilizing supposed cointercalation processes can open the way to a new series of cost-efficient chemical routes for the direct exfoliation of kaolinite.