Intercalation and interlamellar grafting of polyols in layered aluminosilicates. d-Sorbitol and adonitol derivatives of kaolinite

Abstract

This paper reports the intercalation of alditols into the interlamellar spaces of kaolinite. The alditols were adonitol, a meso compound, and D-sorbitol. The grafting of hydroxy groups onto the aluminol internal surfaces of kaolinite followed the intercalation. The polyols were intercalated into kaolinite by displacing dimethyl sulfoxide (DMSO) from the DMSO–kaolinite intercalate (Kao–DMSO). This was done directly from the alditol melt at temperatures just above the melting point of the respective polyols. The intercalated polyols are arranged in a flattened monolayer arrangement, such that the interlayer expansion was 3.1 A (adonitol) and 4.6 A (D-sorbitol). Infrared spectroscopy showed that heating the intercalated materials at 200 °C for 1 h resulted in the grafting of the alditols on the inner aluminol surface of kaolinite. 13C CP and DD/MAS NMR indicated the complete replacement of the DMSO molecules by the alditol guests and that the alditols were rigidly constrained in the interlamellar spaces of kaolinite. The intercalation of adonitol was monitored with time. The reaction proceeds via a partial collapse of the Kao–DMSO intercalate before the intercalation of the adonitol.