Detection of Reversible Nonlinear Dynamic Responses of Polymer Films by Using Time-Resolved Soft-Pulse Compression Attenuated Total Reflection Step-Scan Fourier Transform Infrared Spectroscopy

Abstract

An improved time-resolved soft-pulse dynamic compression attenuated total reflection (ATR) step-scan Fourier transform rheo-optical system has been developed. This system was used to observe reversible dynamic responses of poly(ethyleneterephthalate) (PET) and poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) films. In the case of PET, reversible nonlinear dynamic responses were observed in the C=O stretching vibration. The nonlinear responses decreased with decreasing compressive strain from 0.045 to 0.018. For the C-O stretching bands associated with the backbone structure of the PET, the nonlinear responses were very small. Characteristic burst-like reversible nonlinear dynamic responses can be seen in the in-phase and out-of-phase C=O stretching vibrations of cyclic imides, and phenyl ring deformation bands in the PDA parts of the BPDA-PDA. The results suggest the presence of inter-molecular interaction between C=O of cyclic imides and the phenyl ring groups of the PDA parts. The present method shows promise for characterizing a wide variety of polymeric materials, including polymer alloys, blends, composites, and copolymers and semicrystalline polymers.

Total internal reflection spectroscopy for studying soft matter

“…Similarly, Noda and coworkers averaged over multiple ATR-IR spectra while applying a sinusoidally varying pressure at 2500 Hz to a PET polymer film. 210 An example is shown in figure 24, in which the variation of the IR signal with time does not directly follow the form of the applied pressure.…”

Vacuum FTIR Observation on the Dynamic Hygroscopicity of Aerosols under Pulsed Relative Humidity

“…To address this issue, the PRHCS-RSVFTIR system may be coupled to a step scan accessory. The step scan technique with a nanosecond to millisecond time resolution allows the monitoring temporal progress of transient events, and it has already been applied to the kinetics and spectroscopic studies of organometallic complexes, photobiological systems, combustion processes, radical intermediates, outer membrane protein biogenesis, and adsorption process, etc. − With the step scan mode, the PRHCS-RSVFTIR system can also be used to study heterogeneous reaction kinetics of atmospheric aerosols at a much higher temporal resolution and measure true initial reaction probabilities instead of commonly reported overall reaction probabilities in literature.…”