New types of hyperbranched 1,2,3-triazole-alkoxysiloxane functional polymers for metal embedded nanocomposite surface coatings.

In this study, using the "click-chemistry" azide-alkyne cycloaddition reaction, two new types of polymers, namely, water-soluble amine-functional and water-insoluble pyridine-functional hyperbranched 1,2,3-triazoleorganoethoxysiloxane polymers, capable of stabilizing ultra-small silver nanoparticles and efficient for chemical surface modification were synthesized and characterized by 1H-NMR, 13C-NMR, 29Si-NMR and FT-IR spectroscopy, MALDI and GPC. Coordinatively active hetero-organic polymers with a flexible branched polyethoxysiloxane backbone bearing chelating 1,2,3-triazolyl-dimethylamine and -pyridine conjugated functional groups were exploited towards coordination with Ag+ metal ions, and formation and stabilization of narrowly dispersed silver nanoparticles (Ag-NPs) obtained in the process of radiation induced metal ion reduction. The influence of the chemically assisted radiation process on the Ag-NP size and size distribution was investigated. Hyperbranched polyorganoethoxysiloxanes loaded with Ag-NPs were covalently cross-linked on a Stöber silica surface, demonstrating the efficiency of the developed hetero-organic functional polymers in the preparation of functional nanocomposite coatings for various applications (heterogeneous catalytic systems, antibacterial materials, nanoparticle-based optical sensing devices, etc.). The nanocomposites were investigated and characterized by TEM-EDS, DLS, UV-Vis spectroscopy and 29Si MAS NMR spectroscopy.

Efficient size control of copper nanoparticles generated in irradiated aqueous solutions of star-shaped polyelectrolyte containers.

The formation of copper nanoparticles (Cu-NPs) in irradiated aqueous solutions of star-shaped poly(acrylic acid) (PAA) were studied at two pH values. Transmission electron microscopy (TEM) demonstrates that the star-shaped macromolecules loaded with Cu(2+) ions can act as individual nanosized containers providing a perfect control over the size and size distribution of Cu-NPs. Electron paramagnetic resonance (EPR) and optical spectroscopy show a transformation of mechanisms controlling the reduction of Cu(2+) ions and the further formation of Cu-NPs. At pH 2.9, Cu-NPs are formed from the aquacomplexes of Cu(2+) ions through homogeneous nucleation. At pH 4.3, the formation of Cu-NPs occurs inside macromolecular containers loaded with Cu(2+) ions, which are bound to carboxylic groups of the polyelectrolyte. In the latter case, Cu-NPs apparently ripen from preformed hydrated Cu2O seeds, which are thought to result from the ultrasmall (Cu(2+))m(OH(-))k(COO(-))n species, thus implying a heterogeneous nucleation.

Assembling of Metal-Polymer Nanocomposites in Irradiated Solutions of 1-Vinyl-1,2,4-triazole and Au(III) Ions: Features of Polymerization and Nanoparticles Formation.

Gold nanoparticles (AuNPs) stabilized with poly(1-vinyl-1,2,4-triazole) (PVT) have been synthesized via a one-pot manner in irradiated solutions of 1-vinyl-1,2,4-triazole (VT) and Au(III) ions. The transmission electron microscopy examinations have shown that the sizes of nanoparticles formed range from 1 to 11 nm and are affected by the ratio of VT to gold ions. To study the kinetics peculiarities of the VT polymerization and assembling of AuNPs, UV-Vis spectroscopy was used. The analysis of the data obtained reveals that an inhibition period, influenced by Au(III) concentration, is followed by the polymerization of a monomer. Importantly, the absorbed doses, corresponding to the onset of rapid polymerization, correlate with the doses at which the accelerated formation of AuNPs begins. The kinetics aspects, which could lead to such an effect, are discussed.

Preparation of Biocidal Nanocomposites in X-ray Irradiated Interpolyelectolyte Complexes of Polyacrylic Acid and Polyethylenimine with Ag-Ions.

Due to the presence of cationic units interpolyelectrolyte complexes (IPECs) can be used as a universal basis for preparation of biocidal coatings on different surfaces. Metallopolymer nanocomposites were successfully synthesized in irradiated solutions of polyacrylic acid (PAA) and polyethylenimine (PEI), and dispersions of non-stoichiometric IPECs of PAA-PEI containing silver ions. The data from turbidimetric titration and dynamic light scattering showed that pH 6 is the optimal value for obtaining IPECs. Metal polymer complexes based on IPEC with a PAA/PEI ratio equal to 3/1 and 1/3 were selected for synthesis of nanocomposites due to their aggregative stability. Studies using methods of UV-VIS spectroscopy and TEM have demonstrated that the size and spatial organization of silver nanoparticles depend on the composition of polymer systems. The average sizes of nanoparticles are 5 nm and 20 nm for complexes with a molar ratio of PAA/PEI units equal to 3/1 and 1/3, respectively. The synthesized nanocomposites were applied to the glass surface and exhibited high antibacterial activity against both gram-positive (Staphylococcus aureus) and gram-negative bacteria (Salmonella). It is shown that IPEC-Ag coatings demonstrate significantly more pronounced biocidal activity not only in comparison with macromolecular complexes of PAA-PEI, but also coatings of PEI and PEI based nanocomposites.

One-Pot Preparation of Metal-Polymer Nanocomposites in Irradiated Aqueous Solutions of 1-Vinyl-1,2,4-triazole and Silver Ions.

Metal-polymer nanocomposite polyvinyltriazole-silver nanoparticles were obtained using one-pot synthesis in irradiated aqueous solutions of 1-vinyl-1,2,4-triazole (VT) and silver ions. Gel permeation chromatography data show that upon radiation initiation, the molecular weight of poly(1-vinyl-1,2,4-triazole) increases with increasing monomer concentration. To study the kinetics of polymerization and the features of the radiation-chemical formation of nanoparticles, UV-Vis spectroscopy was used. TEM images show a relatively small average size of the forming nanoparticles (2-3 nm) and a narrow size distribution, which shows the effective stabilization of nanoparticles by triazole substituents at a molar ratio of VT and silver ions of 25/1. The addition of ethyl alcohol was used to increase the efficiency of synthesis and suppress the crosslinking of macromolecules in solution. The results of the work show that aqueous-alcoholic solutions of 1 wt.% VT can be used to obtain soluble nanocomposite materials. 10 wt.% monomer solutions have prospects for use in the preparation of polymer gels filled with nanoparticles.

From triple interpolyelectrolyte-metal complexes to polymer-metal nanocomposites.

Nanocomposite polymer materials containing metal or metal oxide particles attract growing interest due to their specific unique combination of physical and electric behavior. Stoichometric triple interpolyelectrolyte-metal complexes (TIMC) are insoluble in water and in aqueous organic media and may include high content of metal ions; concentration of ions is easy to vary in such polymeric systems. Reduction of metal ions is a common method for obtaining nanoparticles. Interpolyelectrolyte complexes reveal high permeability for polar low-molecular substances and salts. Such swelling behavior is important for the reduction of metal ions included in these solids. The properties of triple interpolyelectrolyte-metal complexes and preparation of nanocomposites from these materials using various methods of metal ion reduction are discussed in this work.