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Reversible thermochromism in thin solid films of poly(3-hexylthiophene), or P3HT, has been studied using ultraviolet and x-ray photoelectron spectroscopies (UPS and XPS, respectively). The UPS and XPS spectra, as well as previously published optical absorption spectra, are analyzed using the results of valence effective Hamiltonian (VEH) quantum chemical calculations of the electronic structure of isolated polymer chains. The analysis of the spectra indicates that at elevated temperatures thermally induced electronic localization occurs as a consequence of thermally induced conformational disorder.

Double mass transfer has been observed spectroscopically and nondestructively for the first time using the x-ray photoemission technique to examine both halves of polymer films touched to other polymer films. A careful selection of polymers according to their peculiar x-ray photoemission spectra enabled the unambiguous identification of polymer fragments on the respective surfaces. The use of the nondestructive XPS or ESCA technique makes possible the observations involving both halves of the contacting pair, and especially the detection of fragments of one polymer on the surface of another. The amount of material transferred is much larger than that necessary to explain triboelectric charging phenomena in terms of mass transfer on a basis of one electronic charge per atom.

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