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Copper, silver and gold nanoparticles were obtained by reduction of metal ions under X-ray irradiation of "layer-by-layer" (LbL) coatings in a water-alcohol medium. The precursors for metal polymer composites (metallopolymer complexes) were prepared by sorption of metal ions in polyethyleneimine - poly (styrenesulfonic acid) and polyethyleneimine - poly (acrylic acid) coatings deposited on cotton fibers. EPR spectroscopy was use to characterize the complexation of metal ions in coatings with different chemical structure and variable number of polyanion-polycation layers. The effect of coating structure and thickness on the size and stability of nanoparticles was studied using TEM and microdiffraction measurements. Antibacterial activity was found for composites containing silver nanoparticles. • Radiation-induced reduction of metal ions in the ultrathin polymer coatings. • Obtaining of nanocomposite antibacterial coatings on the textile fabrics. • The effect of the number of layers of polyelectrolyte on the ions sorption capacity. • Advantages of PEI-PAA as a matrix for metal nanocomposite preparation. [ABSTRACT FROM AUTHOR]

The bimetallic nanostructures are of considerable interest for various prospective applications. This paper reports a generation of the Cu/Ag and Cu/Au nanoparticles in the interpolyelectrolyte films irradiated in aqueous media. It was shown that the radiation-induced reduction of (Cu/Ag) or (Cu/Au) ions in the matrix of poly(acrylic acid)-polyethylenimine complexes led to formation of the nanoparticles with narrow size distribution. The core-shell structure of nanoparticles was demonstrated by the TEM results. According to the X-ray diffraction data, the nanoparticle cores (Ag or Au) are formed at early stage of irradiation, while increase of the absorbed dose results in the growth of copper shell. It was demonstrated that the radiation-induced reduction could be applied for effective preparation of bimetallic nanoparticles directly in the polymer matrix. [ABSTRACT FROM AUTHOR]

The interpolyelectrolyte complexes (IPECs) are widely used for various applications, ranging from agriculture and medicine to advanced technological processes. In many cases, they are subjected to the action of ionizing radiation or hard UV light, either intentionally (e.g., for fabrication of nanocomposites) or in the course of routine treatment (sterilization or weathering), or unexpected accidents. In this communication, we report the first preliminary results on the effect of ionizing radiation on the poly(acrylic acid) (PAA) – polyethyleneimine (PEI) complexes and their components as revealed by EPR spectroscopic studies. The obtained results clearly reveal that the yield of primary radicals trapped after irradiation is comparable in all the studied systems and the main processes are decarboxylation in the PAA moiety and proton loss in the PEI moiety. There are no evidences for main-chain scission, which might lead to the degradation of material properties (at least, at moderate doses), instead of this, the radiation-induced crosslinking looks plausible. Generally, it provides a positive forecast for the radiation resistance of such complexes. • Effect of ionizing radiation on interpolyelectrolyte complexes (IPECs) was studied by EPR. • The radicals produced in the polyacrylic acid – polyethyleneimine IPECs were identified. • No evidence for the radiation-induced destruction of the IPECs was found. • A plausible mechanism of the radiation-induced processes was proposed. [ABSTRACT FROM AUTHOR]

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, γ- 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. [ABSTRACT FROM AUTHOR]