Synthesis and properties of silver and gold nanocomposites in poly-1-vinyl-1,2,4-triazole matrix

Novel multifunctional hybrid nanocomposites with silver and gold nanoparticles stabilized by original polymer matrix based on poly-1-vinyl-1,2,4-triazole were synthesized and studied using UV and IR spectroscopy, X-ray diffraction analysis and transmission electron microscopy. The obtained nanocomposites comprise silver or gold nanoparticles of spherical and elliptical shape with size 3–20 nm and 1–10 nm, respectively.     

Novel nanocomposites based on silver nanoparticles and mixed epoxyamine networks

A procedure has been proposed for the direct synthesis (without the use of reductants) of silver nanoparticles in an epoxy polymer matrix with the formation of novel nanocomposites. The average size of the formed nanoparticles has been shown to be about 18 nm. The polymer cross linking leads to the formation of chain aggregates of the nanoparticles. Nanocomposites containing isolated (individual) silver nanoparticles can also be obtained.     

Synthesis and characterization of silver—poly(methylmethacrylate) nanocomposites

The optical properties of silver nanoparticles embedded in poly(methylmethacrylate) (PMMA) was investigated as well as the influence of silver nanoparticles on the thermal properties of polymer matrix. The average size and particle size distribution of silver nanoparticles was determined using transmission electron microscopy. The obtained transparent nanocomposite films were optically characterized using UV-Vis and FTIR spectroscopy. Thermal stability of polymer matrix was improved upon incorporation of small amount of silver nanoparticles. Also, silver nanoparticles have pronounced effect on thermo-oxidative stability of PMMA matrix. The glass transition temperatures of nanocomposites are lower compared to the pure polymer.     

Silver nanocomposites based on a copolymer of 1-vinyl-1,2,4-triazole with crotonaldehyde

New polymer silver nanocomposites were synthesized using a copolymer of 1-vinyl-1,2,4-triazole with crotonaldehyde as the silver ion reducing agent and stabilizer of metal nanoparticles. The formation of the metallic phase in the nanoscale state was confirmed by UV spectroscopy and X-ray phase analysis. According to the transmission electron microscopy, nanoparticles have sizes of 2—14 nm and are uniformly distributed in the volume of the polymeric matrix.     

Synthesis and optical properties of poly(N-isopropylacrylamide) nanogel containing silver nanoparticles

Composite nanoparticles representing silver nanoparticle-containing polymer gels have been synthesized. The synthesis comprises two main stages. Initially, monodisperse hydrogel particles with a controlled diameter of approximately 500 nm are obtained by N-isopropylacrylamide polymerization. Then, silver ions are reduced on the surface of the polymer network. Variations in the concentration ratio between reductants and silver nitrate make it possible to produce silver nanoparticles with sizes in a range of 10–30 nm and different packing densities on the gel particle surface. The resultant nanocomposites have been studied by transmission electron microscopy, spectrophotometry, and dynamic light scattering. Depending on the size and packing density of the silver nanoparticles on the polymer particle surface, the plasmon resonance of the nanocomposites varies in a range of 420–750 nm, which determines variations in the color of the colloid from yellow, orange, and red to blue and blue-green. After the inclusion of silver nanoparticles, nanogels of poly(N-isopropylacrylamide) retain their capability for thermosensitive phase transition with a lower critical mixing temperature of 31°C.     

Metal-polymer Ag nanocomposites based on hydrophilic nitrogen- and sulfur-containing copolymers: control of nanoparticle size

Russian Chemical Bulletin - New polymer nanocomposites containing silver nanoparticles, stabilized by hydrophilic copolymers of 1-vinyl-1,2,4-triazole with vinylsulfonic acid sodium salt of...     

银/聚合物纳米复合材料

银/聚合物纳米复合材料是一种典型的聚合物基复合材料, 其结构和性能依赖于合成方法,因此开发材料的优异性能必须以深入研究纳米材料的先进合成技术为前提。本文综述了纳米银粒子及其与聚合物形成的纳米复合材料的最新合成进展, 重点介绍了基于液相化学还原方法合成纳米银粒子的新方法, 如溶胶-凝胶法、沉淀法、微乳液法和离子液体法, 以及纳米银粒子的分散技术和原位法合成银/聚合物纳米复合材料的新技术, 并介绍了纳米银复合材料的电绝缘性、表面增强拉曼散射性能、抗菌性及其在生物医学等领域中的应用。     

Synthesis and characterization of silver polymer nanocomposites of 1-vinyl-1,2,4-triazole with acrylonitrile

Novel organic-inorganic nanocomposites were synthesized by chemical reduction of silver ions from silver acetate in DMSO and DMF solutions in the presence of the stabilizing copolymer of 1-vinyl-1,2,4-triazole-acrylonitrile. The solvents DMSO and DMF can act as efficient reducing agents for silver ions, which makes it possible to carry out the reaction under mild conditions and simplify procedures of nanocomposite isolation. The structure and properties of the starting copolymer and related nanocomposites were characterized by UV, IR, and ¹H and ¹³C NMR spectroscopy, as well as transmission electron microscopy and thermogravimetry. The prepared polymer nanocomposites contain 6.8–7.2% silver in the form of nanoparticles with a size of 2–20 nm uniformly dispersed in the polymer matrix. The nanocomposites are readily soluble in DMSO and DMF and do not decompose on heating to 260 °C.     

以葡聚糖-乙二胺聚合物为载体制备纳米银

以葡聚糖-乙二胺聚合物为载体制备纳米银.首先合成葡聚糖-乙二胺聚合物,并用紫外光谱红外光谱对聚合物进行表征;该聚合物与硝酸银反应生成葡聚糖-乙二胺聚合物-银配合物,再通过化学还原或光化学还原法使配合物中的银离子转变成单质银纳米粒,以透射电子显微镜激光纳米测定仪对制备的纳米银进行测定.结果表明制备出了粒径为23.1nm的纳米单质银.以葡聚糖-乙二胺聚合物为载体制备纳米银的方法是可行的.     

Synthesis and biological activity of new polymeric silver-containing nanocomposites

Russian Chemical Bulletin - The formation of new polymeric nanocomposites with silver nanoparticles incorporated into the matrix of 1-vinyl-1,2,4-triazole copolymers with vinyl acetate was studied....     

超声引发无皂乳液聚合制备纳米银/PAAEM复合材料及其表征

在不使用气体保护及乳化剂的条件下,超声辐射引发无皂乳液聚合双原位合成纳米银/聚乙酰乙酸基甲基丙烯酸乙酯(PAAEM)复合材料。并通过XRD、FTIR、TEM、HRTEM、XPS和TG等分析方法对其进行表征。结果表明:纳米银粒子具有面心立方结构和球形或近球形形貌,且较均匀地分散在聚合物基体中;纳米银粒子与基体之间的相互作用是纳米银与基体中乙酰乙酸基的羰基氧原子配位所产生的;而且纳米银粒子对基体PAAEM的热学性能有很大影响。     

A novel synthetic route to metal–polymer nanocomposites by in situ suspension and bulk polymerizations

A novel strategy to synthesize hybrid metal–polymer nanocomposites has been achieved based on in situ free radical suspension and bulk polymerization techniques. An organometallic precursor complex is dissolved in a liquid monomer phase prior to polymerization, where upon the precursor molecules are immobilized inside the polymer matrix during its formation. In a separate step, metal nanoparticles are then formed by H₂-assisted reduction of the precursor in the polymer product in supercritical carbon dioxide (scCO₂). The synthesized nanocomposites were characterized by GPC, TGA, SEM and TEM. It is shown that the metal nanoparticles are uniformly distributed inside the polymer matrix and the inclusion of the metal precursor has no significant influence on the polymerization process. The current work represents a simple and universal way to prepare a variety of metal–polymer nanocomposite functional materials.     

A versatile strategy to fabricate hydrogel-silver nanocomposites and investigation of their antimicrobial activity

In this study, hydrogel-silver nanocomposites have been synthesized by a unique methodology, which involves formation of silver nanoparticles within swollen poly (acrylamide-co-acrylic acid) hydrogels. The formation of silver nanoparticles was confirmed by transmission electron microscopy (TEM) and surface plasmon resonance (SPR) which was obtained at 406 nm. The TEM of hydrogel-silver nanocomposites showed almost uniform distribution of nanoparticles throughout the gel networks. Most of the particles, as revealed from the particle-size distribution curve, were 24-30 nm in size. The X-ray diffraction pattern also confirmed the face centered cubic (fcc) structure of silver nanoparticles. The nanocomposites demonstrated excellent antibacterial effects on Escherichia coli (E. coli). The antibacterial activity depended on size of the nanocomposites, amount of silver nanoparticles, and amount of monomer acid present within the hydrogel-silver nanocomposites. It was also found that immersion of plain hydrogel in 20 mg/30 ml AgNO(3) solution yielded nanocomparticle-hydrogel composites with optimum bactericidal activity.     

Alignment of nanoparticles in polymer matrices

This paper briefly summarizes the state of the art in the field of designing composites containing semiconductor nanoparticles distributed in a polymer matrix. Special attention is focused on (i) nanocomposites based on block copolymers and (ii) LC polymer matrices capable of controlling the localization and alignment of nanoparticles.     

Copolymers of betulin esters and silver nanocomposites based on them

New biologically active silver nanocomposites based on the copolymer of lup-20(29)-ene-3,28-diol 28-O-vinylbenzoate with N-vinylpyrrolidone were prepared by the borohydride method. The formation of spherical nanoparticles with a mean diameter of 67 nm was confirmed by scanning electron microscopy. The synthesized copolymers and silver nanocomposites exhibit cytotoxic activity and show promise for the development of new materials for medical purposes.     

Effect of silver nanoparticles on the morphology,crystallization, and melting behavior of polypropylene: A study on non-isothermal crystallization kinetics

The nanocomposites were prepared using melt intercalation method and the effects of the processing conditions on silver nanoparticles dispersion were investigated by transmission electron microscopy. Non-isothermal crystallization kinetics of virgin polypropylene (PP) and its nanocomposites have been evaluated using differential scanning calorimetric technique. The non-isothermal crystallization melt data were analyzed using macro kinetics equation with the help of Avrami, Malkin, and Mo’s models. The crystallization rate increased with the increasing of cooling rates for virgin PP and nanocomposite, but the crystallization of nanocomposite was faster than that of PP at a given cooling rate. The activation energy for non-isothermal crystallization of virgin polymer and nanocomposites based on Kissinger method has been determined to be 186 and 211 kJ/mol, respectively. Transmission electron microscopy analysis reveals balanced dispersion and presence of some silver nanoparticles aggregates, which act as a heterogeneous nucleating agent during the crystallization of the nanocomposite.     

Preparation of gold-, gold/silver-dendrimer nanocomposites in the presence of benzoin in ethanol by UV irradiation

Gold- and gold/silver-dendrimer nanocomposites have been synthesized by UV irradiation of their salts dissolved in ethanol containing dendrimers. As dendrimers, poly(amidomaine) PAMAM dendrimers and poly(propyleneimine) PPI dendrimers of various generations were used. The photoreduction of their salts is greatly accelerated by using benzoin as a photoinitiator. The sizes of gold in the nanocomposites are affected by the concentration of benzoin as well as the concentration of dendrimers, but are hardly changed with the kind of dendrimers. For gold/silver-dendrimer nanocomposites, the absorption spectra of gold/silver nanoparticles in the nanocomposites are very similar to the theoretical spectra of gold/silver alloy nanoparticles, suggesting the formation of gold/silver alloy nanoparticles. From the comparison of TEM and DLS measurements, it is found that the metal-dendrimer nanocomposites consist of metal nanoparticles covering by dendrimer molecules.     

Silver polymeric nanocomposites as advanced antimicrobial agents: classification, synthetic paths, applications, and perspectives

Utilization of metallic nanoparticles in various biotechnological and medical applications represents one of the most extensively investigated areas of the current materials science. These advanced applications require the appropriate chemical functionalization of the nanoparticles with organic molecules or their incorporation in suitable polymer matrices. The intensified interest in polymer nanocomposites with silver nanoparticles is due to the high antimicrobial effect of nanosilver as well as the unique characteristics of polymers which include their excellent structural uniformity, multivalency, high degree of branching, miscellaneous morphologies and architectures, and highly variable chemical composition. In this review, we explore several aspects of antimicrobial polymer silver nanocomposites, giving special focus to the critical analysis of the reported synthetic routes including their advantages, drawbacks, possible improvements, and real applicability in antibacterial and antifungal therapy. A special attention is given to "green" synthetic routes exploiting the biopolymeric matrix and to the methods allowing preparing magnetically controllable antimicrobial polymers for targeting to an active place. The controversial mechanism of the action of silver against bacteria, fungi and yeasts as well as perspectives and new applications of silver polymeric nanocomposites is also briefly discussed.     

Synthesis of core‐shell silver–polyaniline nanocomposites by gamma radiolysis method

Core‐shell silver (Ag)–polyaniline (PAni) nanocomposites have been synthesized by the in‐situ gamma radiation‐induced chemical polymerization method. Aqueous solution of aniline, a free‐radical oxidant, and/or silver metal salt were irradiated by γ‐rays. Reduction of the silver salt in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline to polyaniline. The resultant Ag‐PAni nanocomposites were characterized by using different spectroscopy analyses like X‐ray photoelectron, UV–visible, and infrared spectroscopy. The optical absorption bands revealed that the bands at about 400 nm are due to the presence of nanosilver and the blue‐shifted peak at ～ 555 nm is due to the presence of metallic silver within the PAni matrix. X‐ray diffraction pattern clearly indicates the broad amorphous polymer and the sharp metal peaks. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the composites have a higher degradation temperature than polyaniline alone. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5741–5747, 2007     

Nanocomposites of polymers and metals or semiconductors: Historical background and optical properties

Upon transmission of visible light through composites comprising of a transparent polymer matrix with embedded particles, the intensity loss by scattering is substantially reduced for particle diameters below 50–100 nm (nanoparticles, nanosized particles). As a consequence, related materials (nanocomposites) have found particular interest in optical studies. The first part of this article deals with a historical survey on nanoparticles and nanocomposites and the importance of small particle sizes on their optical properties. The second part focuses on results from our laboratory concerning nanocomposites with extremely high or low refractive indices and dichroic nanocomposites and their application in bicolored liquid crystal displays (LCD). The inorganic colloids required for these studies (lead sulfide, iron sulfides, gold, and silver) were prepared in situ in presence of a polymer or isolated as redispersable metal colloids modified at the surface with a self‐assembled monolayer (SAM) of an alkanethiol. The nanocomposites themselves were finally obtained by coprecipitation, spin coating, solvent casting or melt extrusion, with poly(ethylene oxide), gelatin, poly(vinyl alcohol) and polyethylene as matrix polymers.