High gamma dose response of poly(vinylidene fluoride) copolymers

Poly(vinylidene fluoride) [PVdF] is a semicrystalline linear homopolymer known worldwide by its good chemical, mechanical and electromechanical properties. Its polymeric chain is composed by the repetition of CH2–CF2 monomers. PVdF and some of its copolymers have demonstrated to be sensitive to ionizing radiation. In this work, we investigate the changes in the ultraviolet–visible (UV–vis) and infrared (FTIR) optical absorbance spectra of poly(vinylidene fluoride–trifluorethylene) [P(VdF–TrFE)] copolymers exposed to high gamma doses, in order to evaluate the possibility of using them as high-dose dosimeters. We have found out a strong linear correlation between the gamma dose and the absorption peak intensities in the UV region of the spectrum, i.e., at 223 and 274 nm. The absorption peak at 223 nm is the most sensitive to gamma rays and can be used for detecting gamma doses ranging from 0.3 to 75 kGy. Simultaneously, the absorption peak at 274 nm can be used for doses ranging from 1 to 100 kGy. Thus, for gamma doses ranging from 1 to 75 kGy, the great advantage of this new high gamma dosimeter is concerned to the ability of evaluating exposed doses at two different wavelengths. FTIR spectrometry data were also used to complement the characterization of the radiation-induced chemical bonds. On the basis of these results we conclude that the P(VdF–TrFE) copolymer is a good candidate for use in high-dose gamma dosimetry applications.