Radiation Functionalization of Optical Properties of PEG MWCNT Nanocomposite Films

The effect of electron irradiation (E_e = 1.8 MeV) on the optical properties of polyethylene glycol 400-multiwalled carbon nanotube (PEG-400/MWCNT) nanocomposite films was studied within an absorbed dose range of 0 to 0.4 MGy. Quantum chemical calculations were performed to optimize the geometry of a 9-unit PEG chain and analyze its infrared (IR) absorption and Raman scattering spectra, as well as charge distribution, molecular orbitals' shape, localization, and energy levels within the electronic band gap, including configurations of electronic transitions. Optical density measurements were conducted for PEG-400/MWCNT films with nanotube concentrations ranging from 0.001 to 0.005 vol part. The percolation dependence of electrical conductivity after irradiation with an absorbed dose of 0.4 MGy was analyzed, along with the fluorescence emission spectra of PEG-400/MWCNT at the same dose. Additionally, Raman spectra were obtained for PEG-400 films irradiated at doses of 0, 0.1, 0.3, and 0.4 MGy, as well as for PEG-400/MWCNT composites exposed to these doses. It was shown that radiation functionalization and nanotube incorporation into PEG-400 exert a complex influence on interchain and interfacial cross-linking. Electron irradiation primarily promotes interchain cross-linking while simultaneously limiting interfacial cross-linking. As the nanotube content increases, carbon nanotubes contribute more significantly to cross-linking degradation and potentially alter the molecular structure of macrochains.