查看文章

The molecular conformation and mobility of the intercalated surfactant molecules cetyltrimethylammonium bromide (CTMAB) have been studied using Fourier transform infrared spectroscopy (FTIR) and high-resolution single-pulse ¹³C magic angle spinning nuclear magnetic resonance (¹³C SP MAS NMR) spectroscopy. The conformation and mobility of alkyl chains were found to be a function of the surfactant concentration. The splitting of the methylene scissoring mode at 1473–1463 cm⁻¹ and the rocking mode at 730–720 cm⁻¹ in FTIR are considered to be diagnostic of the packing density increase of the intercalated surfactants within the clay gallery. Compared with the ¹³C SP MAS NMR spectrum of CTMAB in the bulk state, 1–3 ppm upfield chemical shifts for end-methyl (δC₁₆) and methylene (δC₁₅, δC_2–14) of the intercalated surfactant molecules in the hybrids indicate a freer conformational situation. For …