Wu Q, Li C X, Li X C, Li Y H
State Key Laboratory of Functional Polymer Materials for Adsorption and Separation, Institute of Polymer Chemistry, Nankai University, Tianjin 300071, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2001 Dec;21(6):778-82.
Thermal spectra of liquid crystal, dodecyloxy benzoic acid were collected over a temperature range of 26-150 degrees C by FTIR microspectroscopy. By taking investigations of temperature-induced changes in dodecyloxy benzoic acid by means of 2D infrared correlation spectroscopy, it was possible to clearly describe the molecular dynamic mechanism of dodecyloxy benzoic acid aggregates in the phase transitions. The analysis shows that p-dodecyloxy benzoic acid crystallized as multi-molecule aggregates through hydrogen bonds between the carboxylic groups, while the long polymethylene residues intermixed each other in solid state. Premelting phenomena in polymethylene residues were observed with temperature up to melting point. It seems that lots of oxy-benzoic acid part recrystallized to cycle dimer as supermolecular liquid crystal during alkyl chain melting in crystal-smectic phase transition. After temperature over 132 degrees C, oxy-benzoic acid part were melted to open dimer and separate molecule in liquid state.
通过傅里叶变换红外光谱显微镜在26至150摄氏度的温度范围内收集了液晶十二烷氧基苯甲酸的热谱。通过二维红外相关光谱研究十二烷氧基苯甲酸中温度诱导的变化，能够清晰地描述十二烷氧基苯甲酸聚集体在相变过程中的分子动力学机制。分析表明，对十二烷氧基苯甲酸通过羧基之间的氢键结晶为多分子聚集体，而长的聚亚甲基残基在固态中相互混合。在升温至熔点的过程中，观察到了聚亚甲基残基的预熔现象。在晶体-近晶相转变过程中，烷基链熔化时，似乎许多氧苯甲酸部分重结晶为超分子液晶的环状二聚体。温度超过132摄氏度后，氧苯甲酸部分熔化形成开环二聚体并以液态分离出分子。
