Thermal studies of silverpoly (methylmethacrylate) nanocomposites

The novel nanocomposite material based on surface-modified silver nanoparticles (Np) with average diameter of 6 nm and poly(methylmethacrylate) (PMMA) matrix was synthesized. The effect of silver loading on the thermal properties of PMMA was studied. The obtained transparent nanocomposites Ag/PMMA films were characterized by IR spectroscopy and thermal techniques (TGA, DSC). The chemical composition of the PMMA matrix is not changed in the presence of the metal nanoparticles, but the thermal stability of the nanocomposites was found to be better than thermal stability of the pure polymer. Also, Ag nanoparticles have pronounced effect on a glass transition temperature (Tg) of PMMA.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Interaction of gold nanoparticles with rat brain synaptosomal plasma membrane Na+/K+-ATPase and Mg2+-ATPase

The aim of the work was to investigate the interaction between borate capped gold nanoparticles (AuNPs) and the rat brain synaptosomal plasma membranes (SPM), as well as the effects of these AuNPs on SPM Na+ /K+ - ATPase and Mg2+-ATPase activity. Influence of AuNPs on Na+ /K+ -ATPase and Mg2+-ATPase activity was investigated as the function of AuNPs and protein concentration and preincubation time. AuNPs induced the stimulation of Na+ /K+ -ATPase activity for more than 100%, while Mg2+-ATPase activity reminded unaffected. We propose that this stimulation of enzyme activity was a consequence of an increase of the active surface of membranes.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Synthesis and characterization of crosslinked polyurethanes

Two polyurethane samples, crosslinked with aliphatic hyperbranched polyester, were synthesized and examined in this work. The sample PUPDMS-EO was prepared using ethylene oxide-poly(dimethylsiloxane)-ethylene oxide as macrodiol, while the synthesis of PUPTMO was performed using poly(tetramethyleneoxide). The obtained results show that thermal stability of these networks can be improved by introducing the siloxane sequences. However, the sample PUPDMS-EO has at the same time much lower crosslinking density than PUPTMO.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Rheological and thermogravimetric analysis of unmodified and modified aliphatic hyperbranched polyester

The influence of the type of end groups on the rheological and thermal properties of aliphatic hyperbranched polyesters (AHBP) was investigated in this work. Unmodified, hydroxy-functional AHBP sample of third pseudo generation (AHBP- 3) and the same sample whose end –OH groups were modified with stearic acid (AHBP-3SA) were examined. The presence of the long alkyl chain ends, instead of the polar –OH groups, has reduced the possibility for H-bonding and value of the glass transition temperature. On the other side, by modification of the end –OH groups with stearic acid, thermal stability of AHBP has been improvedPhysical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Surface plasmon resonance of Ag organosols: Experimental and theoretical investigations

The aim of this paper is to investigate and compare the changes in surface plasmon resonance (SPR) of silver (Ag) hydrosol and organosols obtained by experimental and theoretical approaches. Silver nanoparticles (Ag NPs) of 5 ± 1.5 nm in diameter were prepared in water by reduction of silver nitrate with sodium borohydride. Nanoparticles were subsequently transferred into different organic solvents (chloroform, hexane, toluene, 1,2-dichlorobenzene) using oleylamine as a transfer agent. These solvents were chosen because of the differences in their refractive indices. Using UV-Vis absorption spectrophotometry and transmission electron microscopy (TEM), we confirmed that there were no shape and size changes of the nanoparticles upon the transfer to the organic phase. The absorption spectra of the obtained Ag organosols showed only changes in the position of SPR band depending on dielectric property of the used solvent. To analyze these changes, absorption spectra were modelled using Mie theory for small spherical particles. The experimental and theoretical resonance values were compared with those predicted by Drude model and its limitations in the analysis of absorption behavior of Ag NPs in organic solvents were briefly discussed

Thermal properties of nanocomposite film consisting of PVA and shaped Ag nanoparticles

Manipulation of the size and shape of metal nanoparticles has attracted a great deal of attention recently and opened-up possibility for their usage in various fields such as microelectronics and optics. Prismatic and plate-like silver nanoparticles synthesized in water by colloidal chemistry methods, were used as a precursor for preparation of transparent and colored Ag/PVA nanocomposite films. Due to structural anisotropy of prismatic and plate-like silver nanoparticles, confirmed by TEM measurements, in absorption spectrum were observed three surface plasmon resonance bands. In absorption spectrum of Ag/PVA nanocomposite film appears only one absorption band. Interaction between Ag nanoparticles and PVA matrix was followed using FTIR spectroscopy. The thermal properties of Ag/PVA nanocomposite film has been examined using TGA and DSC techniques. The thermal decomposition of the PVA matrix in the presence of shaped Ag nanoparticles is shifted towards higher temperatures for about 14o C in argon atmosphere. Slightly higher thermal stability was obtained during thermo-oxidative degradation process. DSC measurements revealed that shaped Ag nanoparticles incorporated in PVA matrix do not have significant influence on the crystallization temperature changes

Biological and catalytic active nanocomposites of metal nanoparticles (Ag, Au, and Cu) and conductive polymers (polyaniline and polypyrrole) for various applications

A special group of functional materials with advanced features and accordingly promising applications are the nanocomposites of the metal nanoparticles (MNPs) - gold (Au), silver (Ag), and copper (Cu) and intrinsically conductive polymers - polyaniline and polypyrrole [1-7]. Thanks to the characteristics of these MNPs such as tunability of the plasmon resonance through variation of their size, shape, and composition, in combination with polymers, it is possible to create nanocomposites for specific biomedical and catalytic use as a variety of biological/catalytic processes occurring at nanometer scale. These processes are also related to the surface effects of the MNPs, i.e. the reactive (111) crystallographic planes present on their surface, together with the electrical characteristics and morphology of the polymer, as well as the synergistic activity of both components. Biocompatible polymers with good conductivity and electrochemical activity, such as polyaniline or polypyrrole, are good choices for the formation of functional composites with these MNPs, by in-situ polymerization processes. In addition, they protect the MNPs from agglomeration or oxidation and improve their physicochemical characteristics, functions, and variety of applications. The electrocatalytic response of the different prepared nanocomposites for oxygen reduction reaction, and direct borohydride fuel cells, together with their antimicrobial activity, currently investigated in this field in our group, are the subject of the presented work.29th International Symposium on Analytical and Environmental Problems : November 13-14, Szeged, Hungary, 2023

Optical properties of Au nanorods/PVA nanocomposite films

Polymer based nanocomposites have emerged as a new class of materials and attracted considerable interest due to their new or much improved optical, electrical and thermal properties. Au nanorods are synthesized in water using seed-mediated growth method in the present of surfactant CTAB and silver ions. The size and shape of Au nanorods (length-width aspect ratio 4) were examined by TEM technique. Colloidal solution of Au nanorods was used as a precursor for synthesis of Au/PVA nanocomposite films. The optical properties of transparent and colored nanocomposite films were evaluated by UV/ViS absorption spectroscopy. The appearance of two surface plasmon resonance bands in absorption spectrum of Au nanorods colloidal solution is consequence of structural anisotropy. Different dielectric properties of PVA polymer compared to water environment induced position changing of the longitudinal and transversal plasmon resonance bands in absorption spectrum of Au nanorods/PVA nanocomposite films