Assessment the Exposure Effects of Polycarbonate with X-ray Radiation using Spectroscopic Techniques and Molecular Modeling Calculations

Abstract

Abstract In this article, the effects of 6 MeV energy of X-ray radiation on polycarbonate polymeric films were investigated. The induced alterations are assessed using several methodologies: FTIR spectroscopy, contact angle measurements, surface roughness assessment, UV/Vis spectroscopy, and luminescence emission spectroscopy. As well, using the basic sets in the ground state of the polycarbonate structure, the vibrational analysis has been carried out using the density functional theory (DFT). The FTIR spectra display that the X-ray irradiation produces surface chemical alterations in the irradiated films due to successive degradation mechanisms due to the decrease in the detected band peaks. The basis sets that were calculated using the DFT method are in good agreement with the experimentally observed spectra. The frontier molecular orbital energies are used to assess the molecule's energy gap (HOMO-LUMO). The value of the frontier energy gap reflects the chemical reactivity and intermolecular charge transfer that take place within the molecule. The surface wettability behaviors were amended due to the decrease in the contact angle values of irradiated films. This leads to an increase in the surface roughness and surface free energy. X-ray irradiation can enhance the surface goodness of polycarbonate films and control their surface properties to be used in biocompatibility applications. The optical properties of irradiated films show modifications in the studied optical parameters. The absorbance spectra exhibited a shift in the absorption edge of the irradiated samples compared with the pristine one. This shift indicates the decreases in the band gap energy of irradiated samples. For direct transitions, the band gap decreased from 4.03 to 3.125 eV, and for indirect transitions, it decreased from 3.5 0 to 2.65 eV. This result was attributable to the formation of defects and the creation of complex charge transfer due to X-ray irradiation. The photoluminescence emission spectra show that the peak intensities are obviously influenced by increasing the irradiation doses. This is attributable to the band-band transition, donor/acceptor pairs, and bound to free transition, which correlated to the received absorbed dose.