Delamination and Scrolling of the Phyllosilicate Kenyaite

Kenyaite, Na[Si10O20(OH)] · 4H2O, is a phyllosilicate structurally related to Ilerite and Magadiite, whose platy, nonintergrown morphology makes it a promising precursor for high-aspect-ratio nanosheets. Here, Kenyaite is synthesized hydrothermally, fully exchanged with N-methyl-D-glucamine (meglumine), and delaminated via repulsive-osmotic 1D dissolution to yield monolayer silicate nanosheets of about 1.6 nm thickness and micrometer lateral dimensions without significant fracturing. X-ray diffraction, thermogravimetry, and spectroscopy confirm complete interlayer cation exchange, increased interlayer spacing, and preservation of the silicate framework, while light scattering and small-angle X-ray scattering demonstrate individual 2D objects that form nematic, lamellar liquid crystalline phases at high solids content. Upon dilution, the nanosheets spontaneously transform into nanoscrolls with a narrow width distribution and at most a few revolutions, as shown by atomic force microscopy and transmission electron microscopy, revealing scrolling steps consistent with the monolayer thickness. Comparison with Ilerite indicates that surface charge density, pH-dependent deprotonation, and nanosheet size can compensate for increased thickness, so that interfacial chemistry rather than stiffness alone governs the propensity and geometry of scrolling in this family of silicate nanosheets.