Preparation and characterization of conductive and magnetic PPy/Fe3O4/Ag nanocomposites

In this article, conductive and magnetic nanocomposites composed of polypyrrole (PPy), magnetite (Fe₃O₄) nanoparticles (NPs), silver (Ag) NPs, have been successfully synthesized with a two step process. First, the PPy/Fe₃O₄ was prepared by the ultrasonic in situ polymerization. Next, the PPy/Fe₃O₄/Ag was synthesized through the electrostatic adsorption. The products were characterized by fourier‐transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Thermogravimetric (TG), conductivity and magnetization analysis, and the results showed that the Ag NPs with the good conductivity coated uniformly on the surface of PPy/Fe₃O₄ and improved the conductivity of PPy/Fe₃O₄/Ag composites. In addition, as compared with PPy/Fe₃O₄, PPy/Fe₃O₄/Ag composites also have the excellent electro‐magnetic property and enhanced thermostability. POLYM. COMPOS., 35:450–455, 2014. © 2013 Society of Plastics Engineers     

Antibacterial activity and antistatic composites of polyester/Ag‐SiO2 prepared by a sol–gel method

Poly(butylene adipate‐co‐terephthalate) (PBAT) composites containing silver‐silica (Ag‐SiO₂) were prepared using an in‐situ sol–gel process. Maleic anhydride‐grafted PBAT (PBAT‐g‐MA) and multihydroxyl‐functionalized Ag‐SiO₂ were used to improve the compatibility and dispersibility of Ag‐SiO₂ within the PBAT matrix. The composites were characterized morphologically using transmission electron microscopy and chemically using Fourier transform infrared spectrometry. The existence of Ag‐SiO₂ nanoparticles on the substrate was confirmed by the ultraviolet–visible absorption spectra. The antibacterial and antistatic properties of the composites were evaluated whether SiO₂ enhanced the electrical conductivity was tested as well as whether Ag enhanced the antibacterial activity of the PBAT‐g‐MA/SiO₂ or PBAT/SiO₂ composites. The PBAT‐g‐MA/SiO₂ or PBAT/SiO₂ composite that contained Ag had better antibacterial activity (more than 1.3‐fold). The functionalized PBAT‐g‐MA/Ag‐SiO₂ composite can markedly enhanced antibacterial and antistatic properties due to the carboxyl groups of maleic anhydride, which acted as coordination sites for the Ag‐SiO₂ phase, allowing the formation of stronger chemical bonds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electroconductive and catalytic performance of polypyrrole/montmorillonite/silver composites synthesized through in situ oxidative polymerization

The present study demonstrates a simple approach to the formation of polypyrrole/montmorillonite/silver (PPy/Mt/Ag) composites via in situ oxidative polymerization of pyrrole (Py) in the presence of AgNO₃ acting as a direct oxidant. The polymerization was performed in the presence of dodecylbenzenesulfonic acid, which acts as a stabilizing and doping agent. The morphological, structural, and thermal properties of PPy/Mt/Ag composites are discussed in detail and a possible formation mechanism is proposed. The electrical conductivities of the composites pressed at different pressing pressures were investigated using four‐probe analyzer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy results indicated the partially exfoliated structure of the composites and Fourier transforms infrared results suggested the strong interactions between Si? O? Si groups in Mt and N? H groups in PPy chains. The addition of Mt in the PPy polymer enhanced thermal property of the polymer. The conductivity of 1.08 S cm^?1 was observed in the sample with 20 wt % Mt loading and applied pressure of 5 MPa. The composites obtained in the present study catalyze the reduction of methylene blue by sodium borohydride, achieving 92% conversion of MB to colorless within a few minutes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45986.     

Novel Ag/C nanocable/epoxy resin composite

Silver/carbon (Ag/C) nanocables were obtained in the presence of cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions in order to modify epoxy resin. Nanocable is a nanocomposite of nanowire (core) wrapped with one or more outer layers (shell). Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy proved that nanocables consist of a silver nanowire core and a carbon outer shell. The (Ag/C)/epoxy composites were prepared by compounding Ag/C nanocables and epoxy resin. An investigation of the thermal, mechanical, and dielectric properties of these composites showed that the thermal stability and dielectric constant of the composites were enhanced. Interestingly, the breakdown strength of the composites at room temperature increased. Normally, breakdown strength decreases when conducting fillers are added. Fracture morphology of the (Ag/C)/epoxy composite also showed increased toughness. The relationship between the properties and microstructure of the composite was discussed in detail to explain the mechanism behind the change in material properties. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Antibacterial activity of silver photodeposited nepheline thin film coatings

Antibacterial characteristic of silver makes this material very appealing for surface coating on various substrates. In this study, we investigated different silver containing powder for this purpose. Specifically we examined the antibacterial activity of Ag/nepheline compared with Ag/TiO₂ and Ag/SiO₂. Our analysis suggested “Ag/nepheline” composite thin film is an appropriate coating for production of antibacterial ceramic tiles in large scale. In our investigation, FactSage software was used for the thermodynamic analysis. Nano-silver was obtained from silver nitrate solution by ultraviolet illumination of distilled water. In this process, silver was doped on micronized TiO₂, SiO₂, or nepheline. The silver composites and monolithic silver were sprayed with water on raw tiles and sintered in a furnace. Exploring the results suggested the best component for achieving antibacterial tile is Ag/nepheline.     

Synthesis of highly conductive PPy/graphene nanosheets/NiO composite using ultrasonic technique

Highly conductive polypyrrole/graphene nanosheets/NiO (PPy/GNS/NiO) composites are fabricated via ultrasound technique using p‐toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The effects of the GNS and NiO loading on the electrical conductivity are investigated. The maximum conductivity of PPy/GNS/NiO composites about 24.39 S/cm found with 3 wt% GNS and 48.7 wt% NiO at room temperature. The results showed that the high‐aspect‐ratio structure of GNS played an important role in forming a conducting network in PPy matrix. The microstructures of PPy/GNS/NiO are evidenced by the scanning electron microscope and transmission electron microscope examinations. The cyclic voltammetry curves can be seen that the PPy/GNS/NiO composites also have good electrochemical performance, and it can be used as a supercapacitor electrode material. POLYM. COMPOS., 34:997–1002, 2013. © 2013 Society of Plastics Engineers     

Enhancement of the electrical properties of poly(p‐phenylene vinylene) by the incorporation of silicon dioxide nanoparticles

The electrical properties of a poly(p‐phenylene vinylene) (PPV) conjugated polymer using silver (Ag) as a cathode were improved by the incorporation of silicon dioxide (SiO₂) nanoparticles. The current density of the Ag–PPV/SiO₂ nanocomposite system was higher than that of Ag–PPV. A lower level of interfacial oxidation was found in the Ag–PPV/SiO₂ nanocomposite than in Ag–PPV, confirming that a more complete elimination of residue occurred in the nanocomposite. This was due to the relatively large surface area of the PPV/SiO₂ nanocomposite film and the hydrophilic surface of the SiO₂ nanoparticles. The lower level of oxidation contributed to an improvement in the material's current–voltage characteristics. Morphology‐dependent current–voltage characteristics were enhanced by a large variation in the thickness of the Ag–PPV/SiO₂ nanocomposite film because an increased effective field strength could be induced in the thinner regions of the film. The incorporation of SiO₂ nanoparticles altered the effective film thickness and the amount of residue in the interior of the PPV without disrupting the structure of the conjugated polymer. The Ag cathode created a stable interface with the PPV film layer without causing the formation of an organic–metal complex, which would have obstructed electron injection. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

CO adsorption and correlation between CO surface coverage and activity/selectivity of preferential CO oxidation over supported Ag catalyst: an in situ FTIR study

In situ IR measurements for CO adsorption and preferential CO oxidation in H₂-rich gases over Ag/SiO₂ catalysts are presented in this paper. CO adsorbed on the Ag/SiO₂ pretreated with oxygen shows a band centered around 2169 cm^–1, which is assigned to CO linearly bonded to Ag⁺ sites. The amount of adsorbed CO on the silver particles (manifested by an IR band at 2169 cm^–1) depends strongly on the CO partial pressure and the temperature. The steady-state coverage on the Ag surface is shown to be significantly below saturation, and the oxidation of CO with surface oxygen species is probably via a non-competitive Langmuir–Hinshelwood mechanism on the silver catalyst which occurs in the high-rate branch on a surface covered with CO below saturation. A low reactant concentration on the Ag surface indicates that the reaction order with respect to Pco is positive, and the selectivity towards CO₂ decreases with the decrease of Pco. On the other hand, the decrease of the selectivity with the reaction temperature also reflects the higher apparent activation energy for H₂ oxidation than that for CO oxidation.     

Fabrication of carbon nanotubes/polypyrrole/carbon nanotubes/melamine foam for supercapacitor

The carbon nanotubes (CNTs) have been loaded on the melamine foam (MF) to form the composite (CNTs/MF) by dip‐dry process, then polypyrrole (PPy) is coated on CNTs/MF (PPy/CNTs/MF) through chemical oxidation polymerization by using FeCl₃·6H₂O adsorbed on CNTs/MF as oxidant to polymerize the pyrrole vapor. Finally, CNTs are coated on the surface of PPy/CNTs/MF to increase the conductivity of the composite (CNTs/PPy/CNTs/MF) by dip‐dry process again. The composites have been characterized by X‐ray diffraction spectroscopy, scanning electron microscopy and electrochemical method. The results show that the structure of the composites has obvious influence on their capacitive properties. According to the galvanostatic charge/discharge test, the specific capacitance of CNTs/PPy/CNTs/MF is about 184 F g^?1 based on the total mass of the composite and 262 F g^?1 based on the mass of PPy (70.2 wt % in the composite) at the current density of 0.4 A g^?1, which is higher than that of PPy/CNTs/MF (120 F g^?1 based on the total mass of the composite and 167 F g^?1 based on the mass of the PPy). Furthermore, the capacitor assembled by CNTs/PPy/CNTs/MF shows excellent cyclic stability. The capacitance of the cell assembled by CNTs/PPy/CNTs/MF retains 96.3% over 450 scan cycles at scan rate of 20 mV s^?1, which is larger than that assembled by CNTs/PPy/MF (72.5%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39779.     

Conducting polypyrrole‐coated banana fiber composites: Preparation and characterization

In this study, conducting banana fibers (BF) were obtained through in situ oxidative polymerization of pyrrole (Py) on the BF surface using ferric chloride hexahydratate (FeCl₃·6H₂O) as an oxidant. Suitable reaction conditions are outlined for the polymerization of Py: oxidant/monomer molar ratio, Py concentration and polymerization time of 2/1, 0.05 mol.L⁻¹ and 30 min, respectively. Under these conditions, high‐quality conducting fibers containing polyPy and BF (PPy‐BF) were obtained with an electrical resistivity as low as 0.54 Ω.cm. The PPy‐BF was blended with different concentrations of polyurethane (PU) by mixing the two components in a vacuum chamber and then applying compression molding. The electrical resistivity of composites with 25 wt% of PPy‐BF was around 1.8 × 10⁵ Ωcm, which is approximately 10⁸ times lower than that found for pure PU. Moreover, PU/PPy‐BF composites exhibited higher mechanical properties than pure PU and PU/PPy, indicating that these conducting fibers can also be used as reinforcement for polymer matrices. The properties of the PPy‐BF obtained by the method described herein open interesting possibilities for novel applications of electrically conducting fibers, from smart sensors to new conducting fillers that can be incorporated into several polymer matrixes to develop conducting polymer composites with good mechanical properties.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Fabrication and characterization of multilayer SiO2/polymethacrylic acid/polypyrrole composites and hollow polypyrrole microspheres

Methacrylic acid was polymerized on the 3‐(methacryloxy)propyl trimethoxysilane‐modified silica core. The carboxylic acid groups of polymethacrylic acid (PMAA) not only provide the “active‐sites” for growth of the pyrrole monomers but also act as doping acids for polypyrrole (PPy). By in situ polymerization route, SiO₂/PMAA/PPy multilayer composites and hollow PPy microspheres with controllable shell thickness were fabricated. The morphologies, sizes, and structures of the nanocomposites were investigated in detail by transmission electron microscopy, scanning electron microscopy, Fourier‐transform infrared spectra, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and electrochemistry of nanostructured PPy/graphite nanosheets/rare earth ions composites for supercapacitor

Highly conductive PPy/graphite nanosheets/rare earth ions (PPy/nanoG/RE³⁺) composites were prepared via in‐situ polymerization with p‐toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The microstructures of nanoG and PPy/nanoG/RE³⁺ were characterized by the SEM and TEM examinations. It was found that nanoG and PPy nanospheres formed the uniform composite with the PPy nanospheres embedded on the nanoG surface and/or filled between the nanoG. The effects of nanoG and RE³⁺ on the electrical conductivity and electrochemical performance of the composites were investigated. The results showed that the nanoG and RE³⁺ as the filler had effect on the conductivity and electrochemical performance of PPy/nanoG/RE³⁺ composites, which played an important role in forming a conducting network in PPy matrix. A specific capacitance of as high as 175 F/g at a current density of 1 A/g was achieved over the PPy/nanoG/Gd³⁺ composite. The capacitance of the PPy/nanoG/Gd³⁺ composite decreased only 5.1% after 800 charging/discharging cycles at a current density of 1 A/g. POLYM. ENG. SCI., 54:2731–2738, 2014. © 2013 Society of Plastics Engineers     

Studies on electro‐optical properties of polymer matrix/LC/SiO2 nanoparticles composites

Polymer‐dispersed liquid crystal (PDLC) films were prepared by ultraviolet light‐induced polymerization of photopolymerizable monomers in nematic liquid crystal (LC)/monomers/SiO₂ nanoparticles composites, and the effect of SiO₂ nanoparticles on the electro‐optical properties of PDLC films was studied. The observed effect showed that by the adjustment of the SiO₂ nanoparticles content, the refractive index ratio of the LC and polymer could be modulated, and the electro‐optical properties of the polymer matrix/LC/SiO₂ nanoparticles composites could be optimized. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The role of a third component on the conductivity behavior of ternary epoxy/Ag conductive composites

Conductive adhesives, based on highly filled silver particles dispersed in a liquid epoxy resin, with an aliphatic amine [diethyltriamine (DETA)] as a curing agent, were investigated. A third component was added to the epoxy/Ag system to obtain composites of better conductivity, or similar conductivity but at lower silver contents, to modify the conductive adhesive properties, and also to reduce cost. Epoxy/Ag/carbon black (CB), epoxy/Ag/carbon fibrils (CF), epoxy/Ag/SiO₂ and epoxy/Ag/dispersant composites were thus studied. The effect of high curing temperature on the uniformity and resulting conductivity level was also studied. The studied systems, excluding the epoxy/Ag/CB composite, exhibited enhanced conductivities. The microstructure of most of the systems was studied by scanning electron microscopy (SEM). The micrographs produced have served to establish structure‐property relations for better understanding of the observed phenomena.     

Matting films prepared from waterborne acrylic/micro‐SiO2 blends

Acrylic resin/micro‐SiO₂/polymethyl urea (AC/SiO₂/PMU) composites were prepared by physical blends of acrylic resin latex (AC), polymethyl urea resin (PMU), and modified SiO₂. The effects of SiO₂ and PMU content in the hybrid composites morphology and physical properties were investigated in detail using transmission electron microscopy (TEM), UV‐Vis spectrometry (UV‐Vis), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and contact angle measurement. The results showed that introduction of SiO₂ into AC composites could increase the viscosity which caused by gelation and agglomeration of SiO₂. The TEM, SEM images, and TGA results indicated that hybrid membranes have phase separation. During the film formation process, a high number of PMU and SiO₂ particles of an appropriate size were stranded on the surface of the film to form matting surface. These results highlight the sensitivity of the gloss to the polymer morphology and surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41707.     

Synthesis and growth of SiC/SiO2 nanocables decorated with laminated porous ceramics from filter paper and polymericprecursor

A simple and efficient way to synthesize the SiC/SiO₂ nanocables decorated with the laminated porous ceramics by pyrolysis of filter papers impregnated with silicone resins in flowing argon atmosphere has been successfully developed. The phase composition of the laminated porous ceramics was measured by X-ray diffraction. The morphology and microstructure of the samples were analyzed by scanning electron microscopy and transmission electron microscopy. The experimental results show that the nanocables composed of crystalline SiC core coated with a shell of amorphous SiO₂ were observed in the interfacial channels and pores of the laminated ceramics. The diameters of SiC cores were 40–80 nm and the thicknesses of SiO₂ shells were 4–10 nm. The increase of the pyrolysis temperature caused an increase in the amount of SiC/SiO₂ nanocables. Finally, a vapor–liquid–solid (VLS) process was discussed as the growth mechanism of the nanocables.     

Preparation and enhanced electrochemical properties of Ag/polypyrrole composites electrode materials

Ag/polypyrrole (PPy) composites were synthesized with different dispersants via interface polymerization method. The morphology of the composites was investigated by scanning electron microscopy and transmission electron microscopy, and the results showed that the dispersant had strong effect on the morphology of the obtained composites. The structure of the products was characterized by Fourier transform infrared spectroscopy, and X‐ray diffraction. The specific capacitance and impedence of Ag/PPy composites electrode was evaluated through charge/discharge measurements and electrochemical impedance spectroscopy, respectively. Electrochemical performances indicated that Ag/PPy composite electrode used polyvinyl alcohol as dispersant exhibited the highest specific capacitance of 635.5 F/g at a current density of 2.45 mA/g, which provided potential application as supercapacitor materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Application of In Situ Surface-Enhanced Raman Spectroscopy (SERS) to the Study of Citrate Oxidation on Silica-Supported Silver Nanoparticles

Surface-enhanced Raman spectroscopy (SERS) was used to characterize citrate anions adsorbed on nanometer-sized particles of Ag supported on SiO₂. The magnitude of the surface-enhancement effect was determined to be ～3 × 10² on the as-prepared samples of Ag/SiO₂. Upon heating in air above 373 K, the citrate anions undergo oxidation to uni- and bidentate carbonate species and then decomposition to CO₂ and adsorbed O atoms. In the SERS of Ag/SiO₂, a very strong enhancement of the ν(C=O) signal for the bidentate CO₃ species was observed for temperatures between 398 and 448 K, which is accompanied by an increase in the UV–vis absorbance of the sample at the frequency of the laser line used for Raman spectroscopy. This phenomenon is attributed to an increase in the surface-enhancement effect caused by clustering of the Ag nanoparticles as they sinter at elevated temperatures. The present investigation shows that the proper interpretation of in situ SERS spectra requires an understanding of the changes occurring in the UV–vis spectrum of the sample.     

Dynamic mechanical properties of three‐component composites (acrylic polymer/epoxy/SiO2) in the glass‐transition region

In previous studies, we reported the linear and nonlinear rheological properties of three‐component composites consisting of acrylic polymer (AP), epoxy resin (EP), and various SiO₂ contents (AP/EP/SiO₂) in the molten state. In this study, the dynamic mechanical properties of AP/EP/SiO₂ composites with different particle sizes (0.5 and 8 μm) were investigated in the glass‐transition region. The EP consisted of three kinds of EP components. The α relaxation due to the glass transition shifted to a higher temperature with an increase in the volume fraction (?) for the AP/EP/SiO₂ composites having a particle size of 0.5 μm, but the α relaxation scarcely shifted for the composite having a particle size of 8 μm as a general result. This result suggested that the SiO₂ nanoparticles that were 0.5 μm in size adsorbed a lot of the low‐glass‐transition‐temperature (T_g) component because of their large surface area. The AP/SiO₂ composites did not exhibit a shift in T_g; this indicated that the composite did not adsorb any component. The modulus in the glassy state (E′_g) exhibited a very weak &phis; dependence for the AP/EP/SiO₂ composites having particle sizes of 0.5 and 8 μm, although E′_g of the AP/SiO₂ composites increased with &phis;. The AP/EP/SiO₂ composites exhibited a peculiar dynamic mechanical behavior, although the AP/SiO₂ composites showed the behavior of general two‐component composites. Scanning electron microscopic observations indicated that some components in the EP were adsorbed on the surface of the SiO₂ particles. We concluded that the peculiar behavior of the AP/EP/SiO₂ composites was due to the selective adsorption of the EP component. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40409.     

Structural,electrical, thermal,and gas sensing properties of new conductive blend nanocomposites based on polypyrrole/phenothiazine/silver‐doped zinc oxide

The main aim of this study is to investigate the effect of silver‐doped zinc oxide (Ag‐ZnO) loading on the structural, morphological, thermal and electrical properties, and gas sensing behavior of polypyrrole (PPy)/phenothiazine (PTZ)‐blend nanocomposites. The composites are characterized by FTIR, XRD, SEM, TEM, DSC, TGA, and impedance studies. FTIR spectra exhibit the presence of Ag‐ZnO in the PPy/PTZ blend. XRD analysis shows that the semicrystalline behavior of the polymer blend is greatly enhanced by the addition of Ag‐doped ZnO particles. Uniform dispersion of nanoparticles in the polymer is obtained from SEM analysis. The TEM images confirm the presence of spherically shaped nanoparticles in PPy/PTZ blend with a size of 10–25 nm. The DSC measurement indicates that the glass transition temperature of PPy/PTZ blend was significantly improved in the presence of Ag‐doped ZnO nanoparticles. The thermal decomposition temperature of nanocomposite obtained from TGA shows an increase with increase in the content of Ag‐ZnO particles. The incorporation of Ag‐doped ZnO nanoparticles to PPy/PTZ blend exhibit increase in the AC conductivity and dielectric properties of the nanocomposite, due to the pilling of charges at the extended interface of the composite system. The DC conductivity of the nanocomposite increases with the loading of nanoparticles. The ammonia gas sensing performance of PPy/PTZ/Ag‐ZnO nanocomposite is analyzed, and the result shows that the fabricated blend composite can be used as a promising candidate for the easy access of gas molecules. J. VINYL ADDIT. TECHNOL., 26:187–195, 2020. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.