Facile synthesis of lamella mesostructures derived from helix layered silicate and cationic surfactant

Abstract

Lamellar organoammonium silicates were derived from a helix layered silicate (HLS) by the intercalation of cationic surfactant of alkyltrimethylammonium salt. The easy formation of C(n)TMA-HLS lamellar compounds by an intercalation of cationic surfactant molecules was mainly due to the intrinsic property of HLS crystal structure composed with Q(3)-Q(4)-Q(3) silicon networks. When n-alkyltrimethylammonium ions were exchanged with sodium ions, the basal spacings increased with the alkyl chain length, showing the formation of paraffin type surfactant aggregates in the interlayer space. The lamellar structural regularity was affected by the ratio of surfactant to HLS ratio and the initial pH of suspension. The lamellar phase ordering including the crystallinity of HLS framework was not retained during the calcination process and the intercalated cationic surfactant molecules were removed by a repeated extraction with ethanol. C(n)TMA-HLS compounds undergo a drastic structural change at each step of ethanol extraction, and finally transform into less ordered lamellar phases. The removal of surfactants did not destroy the interlamellar structure, but reduced the interplanar spacing significantly.