T. Maluangnont, Kazuaki Matsuba, Fengxia Geng
Jul 19, 2013
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Journal
Chemistry of Materials
Abstract
Osmotic swelling and exfoliation behaviors in a lepidocrocite-type titanate H1.07Ti1.73O4·H2O were investigated upon reactions with tetramethylammonium (TMA+) and tetrabutylammonium (TBA+) cations. The reaction products in various physical states (suspension, wet aggregate, and deposited nanosheets) were characterized by several techniques, including X-ray diffraction under controlled humidity, small-angle X-ray scattering, particle size analysis, and atomic force microscopy. As the ratio of tetraalkylammonium ion in a solution to exchangeable proton in a solid decreased, the predominant product changed from the osmotically swollen phase, having an interlayer spacing d of several tens of nanometers, to the exfoliated nanosheets. The different behaviors of two cations in the osmotic swelling were evident from the slope and the transition point in the d versus C–1/2 plot, where C is the concentration of the cations. At a short reaction time, crystallites of a few stacks were obtained as a major product in t...