title: Formation of organo-highly charged mica.
abstract: The interlayer space of the highly charged synthetic Na-Mica-4 can be modified by ion-exchange reactions involving the exchange of inorganic Na(+) cations by surfactant molecules, which results in the formation of an organophilic interlayer space. The swelling and structural properties of this highly charged mica upon intercalation with n-alkylammonium (RNH(3))(+) cations with varying alkyl chain lengths (R = C12, C14, C16, and C18) have been reported. The stability, fine structure, and evolution of gaseous species from alkylammonium Mica-4 are investigated in detail by conventional thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), in situ X-ray diffraction (XRD), and solid-state nuclear magnetic resonance (MAS NMR) techniques. The results clearly show the total adsorption of n-alkylammonium cations in the interlayer space which expands as needed to accommodate intercalated surfactants. The surfactant packing is quite ordered at room temperature, mainly involving a paraffin-type bilayer with an all-trans conformation, in agreement with the high density of the organic compounds in the interlayer space. At temperatures above 160 °C, the surfactant molecules undergo a transformation that leads to a liquid-like conformation, which results in a more disordered phase and expansion of the interlayer space.
authors.affiliation: Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Avenida Américo Vespucio s/n. 41092 Sevilla, Spain. alba@icmse.csic.es
authors.forename: María D
authors.initials: MD
authors.lastname: Alba
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Castro
authors.forename: M Mar
authors.initials: MM
authors.lastname: Orta
authors.forename: Esperanza
authors.initials: E
authors.lastname: Pavón
authors.forename: M Carolina
authors.initials: MC
authors.lastname: Pazos
authors.forename: Jesús S
authors.initials: JS
authors.lastname: Valencia Rios
mesh_terms: D000538:Aluminum Silicates / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012964:Sodium / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013501:Surface-Active Agents / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D013501:Surface-Active Agents; D012964:Sodium; C011934:mica