聚四氟乙烯F-C-F弯曲振动二维红外光谱研究

Two-Dimensional Infrared Spectroscopy Study of Polytetrafluoroethene F-C-F Bending Vibration

在303~393K的温度范围内,分别测定聚四氟乙烯F-C-F弯曲振动模式(δ_(CF2(PTFE)))的一维红外光谱、二阶导数红外光谱、四阶导数红外光谱和去卷积红外光谱。研究发现:640和620cm^(-1)附近的吸收峰归属于F-C-F面外摇摆振动模式(ω_(CF2-A)和ω_(CF2-B)),550cm^(-1)附近的吸收峰归属于F-C-F剪式振动模式(δ_(CF2)),而500cm^(-1)附近的吸收峰则归属于F-C-F面内摇摆振动模式(ρ_(CF2))。最后研究了聚四氟乙烯二维红外光谱。研究发现:随着测定温度的升高,δ_(CF2(PTFE))吸收强度变化快慢的顺序为:550cm^(-1)(δ_(CF2))>500cm^(-1)(ρ_(CF2))>620cm^(-1)(ω_(CF2-B))>640cm^(-1)(ω_(CF2-A))。本项研究拓展了二维红外光谱技术在聚四氟乙烯材料热变性的方面的研究范围。

The temperature effect of the F-C-F bending vibration mode of polytetrafluoroethene had been studied by one-dimensional infrared spectroscopy, second derivative infrared spectroscopy, fourth derivative infrared spectroscopy and deconvolution infrared spectroscopy in the temperature range from 303 K to 393 K. The polytetrafluoroethene F-C-F wagging vibration mode（ωCF-A and ωCF2- B）occurred respectively near 640 cm^-1 and 620 cm^-1. The band resulting from the scissoring vibration mode（δCF2）appeared near 550 cm ^-1, but the band resulting from the rocking vibration mode（ρCF2）appeared near 500 cm ^-1. Two-dimensional infrared spectroscopy of polytetrafluoroethene were studied to determine the sequence of F-C-F bending vibration mode intensity changes. The relative sequence of intensity changes was given by 550 cm^-1 （δCF2）〉 500 cm^- 1 （ρCF2）〉 620 cm^-1 （ωCF2）） 640 cm-1 （ ωCF2）. The study demonstrated the key roles of two-dimensional infrared spectroscopy in the analysis of thermal denaturation of the polytetrafluoroethene.