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Far-infrared reflection–absorption spectroscopy of thin polyethylene oxide films

1994; American Institute of Physics; Volume: 101; Issue: 4 Linguagem: Inglês

10.1063/1.467657

1520-9032

V. M. Da Costa, Tom Fiske, L. B. Coleman,

Conducting polymers and applications

We report the temperature dependent far-infrared spectrum of ultra-thin films of polyethylene oxide (PEO). Using the orientational specificity of infrared and far-infrared reflection–absorption spectroscopy and in-situ recrystallization, we find that during spin coating the PEO helices are initially in the plane of the film, but on crystallization reorient to be normal to the substrate. A splitting of the C–O torsional mode near 109 cm−1 is identified as arising from a distortion of the normal helical structure of PEO. Comparison with transmission spectra of cast films demonstrates the value of far-infrared reflection–absorption spectroscopy (FIRRAS) in the study of crystalline polymers in the far infrared.