Crystal architectures of a layered silicate on monodisperse spherical silica particles cause the topochemical expansion of the core-shell particles

Abstract

Anisotropic structural changes in an expandable layered silicate (directed towards the c–axis) occurring on isotropic and monodisperse microspheres were detected by measurable increases in the grain size. The hierarchical changes were observed through pursing the sophisticated growth of expandable layered silicate crystals on monodisperse spherical silica particles with diameters of 1.0 μm; the core–shell hybrids with a quite uniform grain size were successfully produced using a rotating Teflon-lined autoclave by reacting spherical silica particles in a colloidal suspension with lithium and magnesium ions under alkaline conditions at 373 K. The size distribution of the core-shell particles tended to be uniform when the amount of lithium ions in the initial mixture decreased. The intercalation of dioctadecyldimethylammonium ions into the small crystals through cation-exchange reactions expanded the interlayer space, topochemically increasing the grain size without any change occurring in the shapes of the core–shell particles.