Abstract
The reaction of protonated magadiite with the cationic surfactant cetyltrimethylammonium (C16TMA) was studied using different C16TMA solutions. The intercalation was achieved from C16TMAOH solution. However, only adsorption of C16TMA cations occurred on the external silicate surfaces from C16TMABr and C16TMACl solutions. Higher pH values were necessary to intercalate C16TMA cations from the bromide or chloride solutions. The intercalated C16TMA cations exhibited good stability in water and in basic (NaOH) solution, which was not the case in acidic (HCl) solution. Raman spectroscopy indicated that the intercalated C16TMA cations exhibited mainly trans conformation similar to the solid C16TMABr with additional gauche conformation. The decomposition temperature of intercalated C16TMA cations occurred at lower temperatures compared to pure C16TMABr. In situ Raman spectroscopy and X-ray diffraction at high temperatures were used to study the thermal stability of the organomagadiites and possible change in conformation during the heating process. In the design of surfactant-modified layered silicates, the strong influence of the surfactant couteranions has to be considered.