Raman spectroscopic study of organo‐montmorillonites

Abstract

A Raman spectroscopic study on the organo-montmorillonites prepared at different concentrations provided detailed observations about the ordering conformation of HDTMA + ions confined within the montmorillonite interlayer. The ordering conformation shows a strong dependence on the concentration of the confined amine. Both the wavenumber and bandwidth of antisymmetric and symmetric stretching modes are sensitive to the ordering conformation of the inserted organic cation. Furthermore, the wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model than in the paraffin-type model. However, at liquid nitrogen temperature, both the positions of antisymmetric and symmetric stretching modes are independent of the amine concentration, and the bandwidth of symmetric stretching mode is sensitive to the organic ordering conformation. Upon heating the organo-montmorillonites, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, indicating a decrease of conformational ordering.

Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR

“…Meanwhile, we can find that ΔδC 16 is bigger than ΔδC 15 , indicating that there is much mobility for C 16 than that for C 15 . This provides the supporting evidence for the proposal that the tail of alkyl chain is movable even in higher packing density of the intercalated surfactants [4]. This was consisted with the result of FTIR that there was a special phase state between solid and liquid in the interlayer even the highest concentration sample.…”

“…In addition, a wide range of molecular environments varying from solidlike to liquidlike was found for the first time. Recently, the conformation of alkylammonium confined in clay interlayer space was extensively studied by techniques of differential scanning calorimetry [1], Raman [4] and NMR [5,6]. These results suggest that the conformation ordering of the intercalated surfactants strongly depends on the loading amount of amine and their orientation.…”

“…In this study, 13 C SP/MAS NMR study, combining with FTIR, is performed on all carbon atoms in the 4 alkyl chain, to probe their local environment and mobility. Our present study provides some new insights about the conformation and dynamic properties of the intercalated alkylammonium ions and their conformation and phase state of organic surfactant in montmorillonite interlayer.…”

Uptake of acid black 210 dye by organo-montmorillonite clay minerals

“…B1h sample showed bands situated at 1470, 1488 and at 723, Figure 2b. According to He et al [14] the presence of doublets at 1467 and 1473 cm -1 by using FTIR spectroscopy with KBr pressed disk technique is indicative of conformational ordering of the chain within the clay interlayer. In Figure 2b, the doublets at 1470-1488 cm -1 of B1h sample may be indicate better ordering of the HDP + in interlayer position than that in B2h sample.…”

“…After conversion to organo-montmorillonite (B1h and B2h), new bands were observed, corresponding to principal bands of the HDP cation, because the natural cations in interlayer position of the montmorillonites were replaced. The bands at 2918 and 2849 cm -1 are typical of bond C-H methylene asymmetric and symmetric mode bond, respectively [14]. The wavenumber of C-H methylene asymmetric band is sensitive to the ordering of carbon in the organic chain [15].…”