Abstract: Fourier transform infrared spectroscopy was used to study solid-solid phase transitions of laurylammonium chloride (LAC) in the temperature range from 290 to 365K. Two structural Phase transitions were observed at 327K and 339K, respectively. In the temperature below 327K, the packing of the hydrocarbon chains is considered to be intercalated with TT conformations. In the temperature between 327 and 339K, the TG defects occured and reached a maximum value at 339K. In this intermediate phase, the nonintercalated packing was found to be coexistent, with the intercalated packing in the intermediate phase. In the temperature above 339K, the packing of the chains is nonintercalated with GT and a few GTG'defects in hexagonal lattice.

Key words: laurylammonium chloride, structural phase transition, molecular conformation, infrared spectroscopy