A comparative study of the effect of O+7ion beam on polypyrrole and CR-39 (DOP) polymers

Polypyrrole thin films doped with para-toluene sulphonic acid were prepared by the electrochemical process. High-energy ion beam irradiation of the polymers is an effective technique to enhance the electrical conductivity, structural property and mechanical properties. So polypyrrole and allyl diglycol carbonate (CR-39 (DOP)) films were irradiated by oxygen ions (energy 100MeV, charge state O(+7)) with fluence varying from 1 x 10(10) to 1 x 10(13) ions cm(-2). The effects of swift heavy ions (SHI) on the structural, optical and surface properties of polypyrrole (Ppy) and CR-39 (DOP) polymers were studied in this work using x-ray diffraction (XRD), UV-visible spectroscopy and scanning electron microscopy (SEM). XRD patterns of the pristine and irradiated polymer show that the crystallinity improved after the irradiation with SHI. At the low fluence, crystallinity was found to increase but at high fluence, it decreases which could be attributed to cross-linking and degradation mechanism. The UV-visible spectra show a shift in the absorbance edge towards higher wavelength, which can be correlated with the transition involved in the polymer and variation in the band gap using Tauc's expression. The band gap of polypyrrole was found to decrease from 3.4 to 3.0 eV after irradiation. CR-39 (DOP), however, showed a very large change in the band gap from 4.8 to 3.4 eV. The SEM study shows a systematic change in the surface morphology of the polymers with increasing ion fluence.