Controlled radiation-chemical synthesis of metal polymer nanocomposites in the films of interpolyelectrolyte complexes: Principles, prospects and implications

The radiation-chemical synthesis of metal nanoparticles embedded into polymer matrices is an effective tool for preparation of the composite materials with very useful functional properties. This paper presents a review of an original approach to a single-step production of such materials via the radiation-induced reduction of the interpolyelectrolyte complex (IPEC) films containing metal ions under heterogeneous conditions, including the most recent results, and analysis of the prospects of this approach and its implications. First, the properties of IPECs as precursors for nanocomposites are briefly considered. Particular impact is given to the mechanistic aspects and principles of control of the nanoparticle formation and assembling at different stages. A common procedure of the radiation-chemical synthesis of metal polymer nanocomposites in the IPEC matrices implies irradiation of swollen films in an aqueous - organic environment. The kinetics of ion reduction and formation of nanoparticles was monitored by EPR and optical spectroscopy, whereas the obtained nanocomposites were characterized by TEM and diffraction methods. Using IPEC matrices allows us to reveal different stages of formation of metal nanostructures over a wide range of absorbed doses. Furthermore, it is possible to manipulate the processes of nucleation and growth of nanoparticles using both physical and chemical factors. Different kinds of radiation (e-beams, gamma- and X-rays) were used in the experiments. It was shown that the penetration depth, dose rate and total absorbed dose had strong effect on the effect on nanoparticle size and their spatial distribution. The most striking feature were found for the processes induced by X-ray radiation. Detailed studies of this particular case revealed a very interesting effect described as radiation-chemical contrast, which is manifested by local intensification of the radiation-induced processes in the vicinity of existing nanoparticles. In addition to metal nanoparticles of different transition and noble metals, it was possible to obtain the bimetallic nanostructures within the IPEC matrix. Such nanocomposites may be potentially used as optical and magnetic materials, sensors, bactericide and fungicide products. The possibility of variation of nanoparticle size and specific properties of the IPEC films is crucially important for particular applications.