The influence of γ-irradiation on some physical properties of chlorophyll/PMMA films

Films of poly(methylmethacrylate) PMMA doped with different concentrations of chlorophyll, from 2.5 up to 12.5 wt.%, have been prepared by casting method. Studies were carried out utilizing FT-IR, UV/vis, fluorescence, TGA and DC electrical conduction to characterize the structural, optical and thermal properties of the films before and after irradiation. Results revealed that the structural and chemical characterizations of PMMA films are affected by the addition of chlorophyll and increasing dose of γ-irradiation. FT-IR analysis revealed that the hydroxyl and carbonyl groups were responsible for the decrease of the bands intensities with increasing the dose rate up to 100 kGy. The change in these groups was attributed to competitive processes: decomposition with ester group abstraction and oxidation with formation of new oxidized carbonyls in the polymeric chains. The values of optical energy gap for the samples were decreased upon irradiation; this indicates that there is a charge transfer complexes arise between PMMA and chlorophyll. TGA analysis shows that the addition of chlorophyll to PMMA films enhances their thermal stability. The electric conduction data were interpreted on the basis of an intrachain one-dimensional interpolaron hopping model of Kuivalainen.