聚对苯二甲酸乙二醇酯反式及左右式构象互变机理研究

采用红外光谱(IR光谱)研究了聚对苯二甲酸乙二醇酯(PET)分子结构。PET亚甲基变角振动模式(δCH2)主要包括:PET亚甲基左右式变角振动模式(δCH2-左右式)和PET亚甲基反式变角振动模式(δCH2-反式)。以PET/δCH2-左右式和PET/δCH2-反式为研究对象,进行了变温红外光谱(TD-IR光谱)研究。实验发现:随着测定温度的升高,PET/δCH2-左右式和PET/δCH2-反式对应的红外吸收频率及强度均有明显的改变,而玻璃化温度(Tg)是一个临界温度。采用二维红外光谱(2D-IR谱),进一步开展了PET反式及左右式构象互变机理研究。拓展了三级IR光谱(包括:IR光谱、TD-IR光谱和2D-IR光谱)在重要的高分子材料(PET)结构及构象转变的研究范围。

Trans and Gauche Conformation Transition Mechanism Research of Polyethylene Terephthalate

The polyethylene terephthalate(PET) structure was studied by infrared spectrum(IR spectrum).The PET CH2 bending vibration mode(δCH2) included CH2 gauche bending vibration mode(δCH2-gauche)and CH2 trans bending vibration mode(δCH2-trans).The temperature-dependent infrared spectrum(TD-IR spectrum) of PET/δCH2-gauche and PET/δCH2-trans were researched also.It was found that with the increase of the measurement temperature,the infrared absorption frequency and intensity of PET/δCH2-gauche and PET/δCH2-trans were changed obviously and the glass transition temperature(Tg) was a critical temperature.Trans and gauche conformation transition mechanisms of PET were further researched by the two dimensional infrared spectrum(2D-IR spectrum).The study expands the research scope of three-step IR spectrum(including:IR spectrum,TD-IR spectrum and 2D-IR spectrum) in the analysis of structure and conformation transition of the important polymer material(PET).