The synthesis of hybrid silver/zinc oxide (Ag/ZnO) decoration on the cellulose surface is described. The structures were characterized with X-ray photoelectron spectroscopy (XPS) and corroborated with X-ray diffraction and scanning electron microscopy. Silver nitrate and zinc acetate dihydrate were used as soluble raw materials. Hexamethylenetetraamine was used as the precipitating and reducing agent. The surface of a-cellulose was always treated by hydrogen peroxide before synthesis with a relatively mild effect manifested in water contact angle measurement and XPS high-resolution spectra. The Ag/ZnO decoration system was identified as a true nanodispersed metal/semiconductor hybrid with a unique collective plasmonic structure observed on Ag 3d core lines for the first time. A series of experiments with a single precursor solution contributed to the characterization of the interaction of Ag ? and Zn 2? species with the surface and to the description of the reaction mechanism in the mixed precursor solution. In contrast to previous reports, a specific interaction between the cellulose substrate and Zn 2? was observed. No specific non-thermal effects of microwave heating were observed.

Magnetic nanoparticles based on Fe3O4 were prepared by a facile and rapid one-pot solvothermal synthesis using FeCl3·6H2O as a source of iron ions, ethylene glycol as a solvent and NH4Ac, (NH4)2CO3, NH4HCO3 or aqueous NH3 as precipitating and nucleating agents. In contrast to previous reports we reduce the synthesis time to 30 minutes using a pressurized microwave reactor without the requirement of further post-treatments such as calcination. Dramatically reduced synthesis time prevents particle growth via Ostwald ripening thus the obtained particles have dimensions in the range of 20 to 130 nm, they are uniform in shape and exhibit magnetic properties with saturation magnetization ranging from 8 to 76 emu g(-1). The suggested method allows simple particle size and crystallinity tuning resulting in improved magnetic properties by changing the synthesis parameters, i.e. temperature and nucleating agents. Moreover, efficiency of conversion of raw material into the product is almost 100%.

The preemergence chloroacetamide herbicide metazachlor was encapsulated in biodegradable low molecular weight poly(lactic acid) micro- and submicroparticles, and its release to the water environment was investigated. Three series of particles, S, M, and L, varying in their size (from 0.6 to 8 μm) and with various initial amounts of the active agent (5%, 10%, 20%, 30% w/w) were prepared by the oil-in-water solvent evaporation technique with gelatin as biodegradable surfactant. The encapsulation efficiencies reached were about 60% and appeared to be lower for smaller particles. Generally, it was found that the rate of herbicide release decreased with increasing size of particles. After 30 days the portions of the herbicide released for its highest loading (30% w/w) were 92%, 56%, and 34% for about 0.6, 0.8, and 8 μm particles, respectively. The release rates were also lower for lower herbicide loadings. Metazachlor release from larger particles tended to be a diffusion-controlled process, while for smaller particles the kinetics was strongly influenced by an initial burst release.

Hybrid silver/zinc oxide (Ag/ZnO) nanostructured microparticles were obtained via the fast and simple microwave-assisted synthesis. The phase structure of filler particles was revealed by X-ray diffraction analysis. Composites with medical-grade poly(vinyl chloride) were prepared with filler concentration from 1 to 5 wt%. The scanning electron microscopy was used for morphology characterization and elemental analysis of both filler and composites. The mechanical properties of composites and the electrical resistivity were found suitable for medical device application. The excellent surface antibacterial performance of the prepared composite tested according to ISO 22196:2007 against Escherichia coli and Staphylococcus aureus showed the reliability of the material in the medical application field. POLYM. COMPOS., 00:000-000,

One of the crucial problems of classical magnetorheological (MR) fluids is their high rate of sedimentation. This disadvantage may be substantially eliminated using core-shell particles. The aim of this study is to prepare spherical carbonyl iron (CI) particles coated with conducing polymer polypyrrole (PPy) with ribbon-like morphology. Scanning electron microscopy proved the formation of the ribbon-like layer onto CI particles while Fourier transform infrared spectroscopy confirmed the chemical structure of PPy. The magnetic properties observed via vibrating sample magnetometer showed decreased magnetization saturation of coreshell-structured particles due to the existence of non-magnetic surface layer. MR measurements performed under oscillatory shear flow as a function of the applied magnetic flux density, temperature, and particle concentration showed that core-shell particle-based MR suspension exhibits sufficient MR performance for practical applications. Moreover, the suspension stability is promoted significantly when core-shell particles are used as a dispersed phase.

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This work focuses on an inkjet-fabricated sensor based on copper oxide nanostructured particles on polymer flexible substrate for the sensing of alcohol vapours and humidity at room temperature. Nanoparticles were prepared by a microwave-assisted solvothermal sealed vessel synthesis method. The ink composition was developed on the basis of viscosity and surface tension optimization by the addition of polymeric steric surfactant and dispersant. The printing process was optimized with the help of non-dimensional criteria. Silver nanoink was used for the printing of an interdigitated pattern on a PET substrate which was overprinted by the copper oxide ink, thus obtaining a flexible flat sensor. Material design and all fabrication steps of the sensor respected the temperature limitation given by the thermal stability of the polymer substrate. Printed layers and motifs were characterized microscopically and by resistance measurement. The effectiveness of the prepared sensor was demonstrated and studied by measuring the response to saturated vapours at room temperature. The sensing layer showed the opposite resistance response to stimuli than expected for the well-known p-type sensing mechanism of CuO sensors operated at high temperatures. In addition to vapour sorption, condensation and desorption influencing electron, proton and ionic conductivity, manifestation of another mechanism was observed and an explanation suggested in terms of the electrochemical mechanism.