Abstract

The interstratified layer nano-hybrids between n-alkylammonium and fluorine mica are prepared by ion-exchanging the interlayer Na⁺ ions in the synthetic fluorine mica, Na_0.66Mg_2.68(Si_3.98Al_0.02)O_10.02F_1.96, with n-alkylammonium cations, CH₃(CH₂)_n − 1NH₃⁺ (C_n; n = 6, 8, 10, 12, 14, 16, and 18). According to the X-ray diffraction profiles of nano-hybrids and their computer simulation results, their interstratified structural features could be clearly distinguished depending upon the number of carbon atoms in the alkyl chain (C_n). The C₆–C₈ and C₁₄–C₁₆ derivatives exhibit normal intercalation phases with the basal spacings of ∼13.8 Å and ∼18.0 Å, indicating the parallel mono- and bilayer arrangements of the intercalants between silicate layers, respectively. On the other hand, the C₁₀–C₁₂ and C₁₈ hybrids show distinct superlattice lines in the X-ray diffraction patterns due to the interstratification between parallel monolayer–bilayer (d₀₀₁ = 31.6 Å) and parallel bilayer–pseudotriple layer (d₀₀₁ = 39.6 Å) of alkylammonium molecules, respectively, in the interlayer space of mica. The origin of such interstratification is found to be due to the charge heterogeneity of silicate interlayers in the Na⁺-fluorine mica; a high layer charge with 0.37 e⁻/Si₄O₁₀ and a low one with 0.28 e⁻/Si₄O₁₀ charge densities, respectively. The charge heterogeneity of silicate layers is also confirmed through the step-wise deintercalation of intercalants during their thermolysis under a nitrogen atmosphere.