Title: Polymeric materials transformation under exposure by a megawatt pulse flux of submillimeter radiation (First realization)
Abstract:
Complex supramolecular structures form the basis of biologically active compositions for pharmaceutical applications, energetic materials, and various functional materials and the materials structure determine their functional properties. The material structure is manifested in the phonon vibration spectrum, which extends from fractions of a terahertz to several terahertz. Exposure of such supramolecular systems to radiation flux in this frequency range enables significant modification of structural changes accompanied by significant modification of the population of states within the phonon spectrum. Thus, the use of intense radiation flux in the terahertz range appears promising not only for the characterization of supramolecular systems but also for the targeted modification of their structural features and functional properties.
As a first step in this line of research, we carried out studies on the effect of pulsed megawatt radiation fluxes in the frequency range of 0.1–0.4 THz on several thin-film polymer materials, with the goal of identifying regularities in the changes of their characteristics within the 0.2–2 THz interval. The test samples were thin polymer films, 16–75 μm thick, fixed in a frame. The exposure was performed using a submillimetre radiation flux generated at the GOL–PET facility. This radiation flux is produced through intense interaction of a relativistic electron beam with a magnetized plasma column. The flux is subsequently delivered into the atmospheric conditions of the experimental hall to irradiate the samples. The spectral characterization of the thin-film samples in the specified frequency range was performed before and after exposure using equipment operating within the frameworks of time-domain spectroscopy and backward-wave oscillator (BWO) spectroscopy. Relative changes in the real part of the permittivity of individual polyvinylidene fluoride samples were found to reach a level of 0.5 with an initial value of about 3.0, while for polyvinyl chloride samples, no changes in this parameter were registered. For series of various polyuria samples this parameter demonstrated both significant and negligible changes at the exposure. On the base of these obtained results, we can use the tested thin-film polymer materials as substrates for supramolecular complex samples at their irradiation by powerful radiation fluxes. Synchrotron radiation diagnostic —specifically, small-angle X-ray scattering and grazing-incidence X-ray diffraction will be additionally applied to characterize the structure characteristics of these samples.
