Electronic properties of polypyrrole based TiO2 nanofiber composite

In this work, Polypyrrole (PPy), Titanium dioxide nanofiber (TiO₂‐nf) are prepared by oxidative polymerization and hydrothermal process respectively. The PPy/TiO₂‐nf composite is prepared by in situ oxidative polymerization in the presence of pyrrole monomer and TiO₂‐nf. The nanocomposite and TiO₂‐nf are then characterized by scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX) techniques and XRD studies. Dielectric studies of PPy/TiO₂‐nf composite is carried out in the frequency range of 1 KHz‐3 MHz at varying temperature and it shows anomalous behavior at 1MHz, where its value reaches to its minimum value of 13 at room temperature and this dip remains even at higher temperature. Impedance study is used to understand the grain and grain boundary effects of the material; frequency dependent ac conductivity has two regions separated at 1MHz, which is being explained by hopping conduction and Maxwell‐Wagner type mechanism, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40036.     

Synthesis and characterization of montmorillonite/polypyrrole nanocomposite

A novel montmorillonite (MMT)/polypyrrole (PPy) nanocomposite (MPN) with high electrical conductivity and thermal stability has been synthesized via in‐situ polymerization. The surface morphology, characterization, thermal stability, and electrical conductivity have been tested by scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and four‐probe methods, respectively. SEM results show that the antenna‐like PPy deposits on the layer surface of MMT. FTIR and XRD analyses show that there is interaction between MMT and PPy. The nanocomposite has high electrical conductivity (4 S/cm), eight orders of magnitude higher than that of pristine MMT. The thermal stability of MPN is higher than the pure PPy as well as the mixture of MMT and PPy (MMP). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Visible‐Light‐Induced Degradation of Methylene Blue by SrBi3VO8 Nanoparticles

Nanosized particles of strontium bismuth vanadate SrBi₃VO₈ were prepared via the Pechini method on the base of citrate‐complexation route. The samples were characterized using X‐ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X‐ray spectra (EDX), X‐ray photoelectron spectroscopic (XPS), and UV–vis absorption spectrum. This bismuth‐containing vanadate presents an efficient absorption in the UV–visible light wavelength region with a narrow band‐gap energy of 2.36 eV and an indirect allowed electronic transition. It is well‐known that hybridization of the 6s and 6p orbitals of Bi³⁺ could result in lone electron pair and yield some very interesting properties. The photocatalytic activities of SrBi₃VO₈ nanoparticles were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation in air atmosphere. These results indicate that SrBi₃VO₈ could be a potential photocatalyst driven by visible light. To understand the charge generation and separation process, the luminescence as well as the decay lifetimes was investigated in the same samples for photocatalysis.     

Composite sodium p‐toluene sulfonate–polypyrrole–iron anode for a lithium‐ion battery

In this study, p‐toluene sulfonate (TsONa) doped polypyrrole (PPy) was synthesized for an anode in a lithium‐ion battery via a one‐step facile electropolymerization on Fe foil. The obtained TsONa–PPy–Fe composite electrode was investigated with scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and galvanostatic charge–discharge profiling. As expected, many irregular microspherical particles of TsONa‐doped PPy formed and combined tightly with the surface of Fe foil. Furthermore, the obtained TsONa–PPy–Fe anode also delivered satisfactory electrochemical performances. For example, the reversible capacity was still about 105–115 mAh/g, even after at least 50 cycles. The high lithium storage activity of PPy and the high conductivity of the TsONa‐doped PPy jointly contributed into the satisfactory electrochemical performances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44935.     

Antibacterial property on Gram‐positive bacteria of polypyrrole‐coated fabrics

Antibacterial activity against Gram‐negative bacteria of polypyrrole‐coated fabrics has been demonstrated in the past. In this work, biocidal efficacy of polypyrrole has been evaluated against Gram‐positive bacteria on textiles with different polypyrrole loading. Excellent bacterial reduction (≥99%) was found on cotton fabrics containing more than ～9 wt % of polypyrrole. Polypyrrole loading can be greatly reduced in presence of silver. Silver‐containing fabrics used in this work alone does not guarantee a complete biocidal effect, but the addition of just 2 wt % of polypyrrole showed a bacteria reduction of 99%. Moreover, stability to different washing procedures of the antibacterial activity was evaluated. Fabrics were characterized by scanning electron microscopy, energy dispersive X‐ray analysis, and infrared spectroscopy. Stability of the coating was assessed by abrasion tests. PPy showed excellent fastness to abrasion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41670.     

Synthesis and electrochemical properties of graphene oxide/nanosulfur/polypyrrole ternary nanocomposite hydrogel for supercapacitors

A method for synthesizing Graphene oxide (GO)/nano‐sulfur/polypyrrole (PPy) ternary nanocomposite hydrogel is depicted. The higher surface area of GO, PPy porous structure and their excellent conductivity are utilized, and the GO hydrogel can be made easily. The products are characterized by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and electrochemical workstation. The results demonstrated that GO/nano‐S/PPy ternary nanocomposite hydrogel is successfully synthesized. The electrochemical properties are investigated by cyclic voltammetry, galvanostatic charge/discharge measurements, and cycling life in a three‐electrode system in 1M Li₂SO₄ electrolyte solution. The GO/nano‐S/PPy ternary nanocomposite hydrogel exhibit a high specific capacitance of 892.5 F g^?1 at scan rates of 5 mV s^?1 and the capacitance retain about 81.2% (594.8 F g^?1) of initial capacitance (732.5 F g^?1) after 500 cycles at a current density of 1 A g^?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40814.     

A facile route for the synthesis of nanotubular composite of polyaniline with cobalt and its superparamagnetism below blocking temperature

We have prepared nanotubular composite of polyaniline with cobalt from the reverse micelle of sodium dioctyl sulfosuccinate and n‐hexane. Samples are characterized with characterized by X‐ray diffractometer (XRD), transmission electron microscopy, field emission scanning electron microscope, energy dispersive spectroscopy (EDS), Fourier transformed‐infrared spectrums (FTIR), thermo gravimetric analysis, differential scanning calorimeter, and vibrating sample magnetometer. XRD patterns shows metastable ε‐cobalt phase in the composite. Tube like morphology with average diameter of 25–35 nm and length up to 1 µm is obtained. Peak assignment of FTIR spectrum reveals that green solid material is polyaniline and incorporation of cobalt in polyaniline matrix leads structural change. EDS also indicates the presence of cobalt in the nanocomposite. Enhancement in thermal stability is obtained for nanocomposite. Superparamagnetism is obtained in the nanocomposite from dc magnetic measurement and ac susceptibility measurement. POLYM. COMPOS. 36:489–496, 2015. © 2014 Society of Plastics Engineers     

Chemical Grafting of Crosslinked Polypyrrole and Poly(vinyl Chloride) onto Modified Graphite: Fabrication,Characterization, and Material Properties

ABSTRACT

Conjugated polymer/graphite nanocomposites have been known as high performance materials owing to improve the physicochemical properties relative to conventional once. Multilayered polymer nanocomposites based on polypyrrole (PPy), polyvinylchloride (PVC) as matrices and p-phenylene diamine (PDA) as linker were prepared via chemical in situ polymerization process and subsequently investigated the physical characteristics of fabricated nanocomposites at various loadings. The structural characterization and morphology of prepared nanocomposites were inspected by Fourier transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS), energy dispersive X-ray spectroscope (EDX), field emission scanning electron microscope (FESEM), respectively. The composite III showed higher thermal stability at 10 wt% loading of PPy. According to differential scanning calorimetry (DSC), the glass transition temperature (T_g), melting temperature T_m, and crystallization temperature (T_c) of nanocomposites increases with PPy loading (2–10 wt%) owing to crosslinking and chain rigidity. Moreover, higher surface area was displayed by the multilayered PPy/PVC/PDA@FG nanocomposites. Remarkably, electrical conductivity of ultimate nanocomposites was also found to be a function of PPy loading.     

Electrical and microwave absorbing properties of polypyrrole synthesized by optimum strategy

The polypyrrole (PPy) was prepared by in situ solution polymerization. The structure and morphology were characterized by X‐ray diffractometry, scanning electron microscope (SEM), and transmission electron microscope, respectively. The electrical and dielectric properties of the PPy were measured by four‐point technique and impedance/materials analyzer. The results revealed that reaction time, reaction temperature, the types of doping agent, and the molar ratio of initiator to pyrrole monomer (n_APs/n_Py) had an important effect on electrical and dielectric properties of the PPy. It showed that the PPy doped with phosphoric acid and with n_APs/n_Py = 1 at 10°C for 12 h had better performance of electrical conductivity and dielectric loss. The PPy sample with 2 mm thickness had a minimum reflection loss value of ?19.68 dB at approximately 16 GHz and an available bandwidth of 6.2 GHz in the range of 8–18 GHz. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of chemically and electrochemically prepared conducting polymer/iron oxalate composites

Poly(3-octyl-thiophene) (POT) and polypyrrole (PPy) iron oxalate composites were synthesized through a post-polymerization oxidative treatment. The composite of the latter has been prepared also by electrochemical polymerization. The samples have been characterized by X-ray diffraction (XRD), impedance spectroscopy, scanning electron microscope (SEM) combined with energy dispersive X-ray (EDX) spectroscopy, Mössbauer spectroscopy, cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). In case of PPy, two peaks in the XRD spectra show the presence of iron containing composite, while with POT only the layered structure originating from the octyl side-chain interactions was modified by the composite formation. The assumption of the weakening of short- and long-range interactions was proven by the decrease in conductivity of the composite. The successful electrochemical synthesis resulted a composite of ∼5% iron content, determined by EDX. Mössbauer spectroscopy measurements evidenced a composite containing mixed valence iron oxalate doping ions, which supports the indirect EQCM data.     

Characterization and physical properties investigation of conducting polypyrrole/TiO2 nanocomposites prepared through a one‐step “in situ” polymerization method

Nowadays, nanocomposites are a special class of materials having unique physical properties and wide application potential in diverse areas. The present research work describes an efficient method for synthesis of a series of polypyrrole/titanium dioxide (PPy/TiO₂) nanocomposites with different TiO₂ ratios. These nanocomposites were prepared by one‐step in situ deposition oxidative polymerization of pyrrole hydrochloride using ferric chloride (FeCl₃) as an oxidant in the presence of ultra fine grade powder of anatase TiO₂ nanoparticles cooled in an ice bath. The obtained nanocomposites were characterized by Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The obtained results showed that TiO₂ nanoparticles have been encapsulated by PPy with a strong effect on the morphology of PPy/TiO₂ nanocomposites. Also, the synthesized PPy/TiO₂ nanocomposites had higher thermal stability than that of pure PPy. The investigation of electrical conductivity of nanocomposites by four‐point probe instrument showed that the conductivity of nanocomposite at low TiO₂ content is much higher than of neat PPy, while with the increasing contents of TiO₂, the conductivity decreases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of polypyrrole/clinoptilolite nanocomposite with enhanced electrical conductivity by surface polymerization method

In this work, polypyrrole/clinoptilolite nanocomposite was synthesized by in situ surface polymerization of pyrrole using Fe³⁺ as oxidant, incorporated on the inner and outer surface of clinoptilolite nanoparticles. Formation of nanocomposite and deposition of polypyrrole on the clinoptilolite surface was confirmed and characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and cyclic voltammetry techniques. Elemental analysis showed the loading/incorporation of 9.18 wt% polypyrrole in the clinoptilolite structure. However the electrical conductivity of polypyrrole/clinoptilolite nanocomposite pellets was higher than that of similar pure polypyrrole pellets, synthesized through the chemical oxidation polymerization method using Fe³⁺ as oxidant without the presence of clinoptilolite nanoparticles. Improved structural order or crystalinity of polypyrrole chains in nanocomposite structure which was confirmed by XRD and SEM results, may be the responsible of higher electrical conductivity of nanocomposite compared to pure polypyrrole although the low content (9.18 wt%) of polypyrrole in nanocomposite. Cyclic voltammetry studies showed that polypyrrole/clinoptilolite nanocomposite is electroactive similar to pure polypyrrole. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Conversion of pencil graphite to graphene/polypyrrole nanofiber composite electrodes and its doping effect on the supercapacitive properties

Graphene platelets were synthesized from pencil flake graphite and commercial graphite by chemical method. The chemical method involved modified Hummer's method to synthesize graphene oxide (GO) and the use of hydrazine monohydrate to reduce GO to reduced graphene oxide (rGO). rGO were further reduced using rapid microwave treatment in presence of little amount of hydrazine monohydrate to graphene platelets. Chemically modified graphene/polypyrrole (PPy) nanofiber composites were prepared by in situ anodic electropolymerization of pyrrole monomer in the presence of graphene on stainless steel substrate. The morphology, composition, and electronic structure of the composites together with PPy fibers, graphene oxide (GO), rGO, and graphene were characterized using X‐ray diffraction (XRD), laser‐Raman, and scanning electron microscopic (SEM) methods. From SEM, it was observed that chemically modified graphene formed as a uniform nanocomposite with the PPy fibers absorbed on the graphene surface and/or filled between the graphene sheets. Such uniform structure together with the observed high conductivities afforded high specific capacitance and good cycling stability during the charge–discharge process when used as supercapacitor electrodes. A specific capacitance of supercapacitor was as high as 304 F g^?1 at a current density of 2 mA cm^?1 was achieved over a PPy‐doped graphene composite. POLYM. ENG. SCI., 55:2118–2126, 2015. © 2014 Society of Plastics Engineers     

Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization

The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, X‐ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m^?1 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41800.     

Antibacterial and antifungal dressings obtained by photochemical deposition of silver nanoparticles

The antimicrobial activity of silver against a wide spectrum of bacteria, fungi and viruses is known since antiquity. Silver has been used as topical antimicrobial agent in the treatment of wounds since many years and advanced silver‐based dressings have been designed so far. The aim of this study was the development of low‐cost antibacterial and antifungal dressings through the surface modification of conventional cotton gauzes. Different percentages of silver were deposited on textile substrates by adopting an innovative silver deposition technique based on the photochemical deposition of silver nanoparticles. The uniformity of the coating and the distribution of the silver clusters on the surface were evaluated by scanning electron microscopy (SEM). The amount of silver was quantified by thermogravimetric analysis (TGA) and the presence of metallic silver nanoparticles was also assesses through UV–Vis–NIR with integrating sphere and energy dispersive X‐ray spectroscopy EDX. The effectiveness of the silver treated textile was verified on different microorganisms, namely Escherichia coli, Staphylococcus aureus, Pseudomonas p43 and Candida albicans derived from a clinical isolate. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40326.     

Synthesis of hierarchical structured porous MoS2/SiO2 microspheres by ultrasonic spray pyrolysis

Hierarchical structure porous MoS₂/SiO₂ microspheres were prepared by ultrasonic pyrolysis technique. The nanostructured MoS₂/SiO₂ materials were characterised by scanning electron micrograph (SEM), energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), high‐resolution transmission electron microscope (HRTEM), as well as nitrogen isotherm. The MoS₂/SiO₂ microspheres, synthesised using polystyrene latex spheres as a template, showed two pore sizes: 5.8 and 68 nm. The micro‐, meso‐ and macropore volume was also calculated. Effect of PSL:SiO₂ ratio on the hierarchical structure was also investigated. © 2011 Canadian Society for Chemical Engineering     

Synthesis and characterization of polypyrrole using TiO2 nanotube@poly(sodium styrene sulfonate) as dopant and template

A polypyrrole (PPy) using TiO₂ nanotube@poly(sodium styrene sulfonate) (TiO₂@PSS) as dopant and template was synthesized by chemical oxidation polymerization. The template TiO₂@PSS consisting of a TiO₂ nanotube core and PSS on the surface was prepared by a “grafting from” approach. PPy on the layer of TiO₂@PSS (TiO₂@PSS/PPy) was characterized by transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectrometry (FTIR), Raman spectroscopic analysis, UV‐visible (UV‐vis) spectroscopy, thermo gravimetric analysis, and electrical conductivity analysis. Results showed that TiO₂@PSS/PPy was successfully fabricated. The electrical conductivity of the TiO₂@PSS/PPy nanocomposites at room temperature was 11.6 S cm⁻¹, which was higher than that of the PPy (4.2 S cm⁻¹). This result was consistent with those based on FTIR, UV‐vis spectroscopy, and XPS analyses. The nanocomposites have nanoparticle size and controllable morphology and thus potential applications in photoelectrochemical devices, photocatalytic devices, conductive inks, electronic printing sensors, and electrodes. POLYM. COMPOS., 37:462–467, 2016. © 2014 Society of Plastics Engineers     

Characterization and charge transfer mechanism of PIN–cdse nanocomposites

This paper reports structural, thermal, and temperature‐dependent dielectric properties of polyindole–cadmium selenide (PIN–CdSe) nanocomposites. PIN and its nanocomposites were synthesized via in situ chemical oxidative polymerization method. Samples were characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), scanning electron microscopy with energy dispersive X‐ray (SEM/EDX), atomic force microscope, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Dielectric properties were analyzed as a function of temperature. FT‐IR spectroscopy indicated that both N H and aromatic CC bonds were affected more by doping process. Significant structural differences were observed in XRD and SEM analyses of PIN and its nanocomposites. Both XRD and DSC measurements revealed that crystallinity of the PIN increases to a certain degree with increasing doping level. Thermogravimetric analysis showed that addition of CdSe decreased degradation temperature of the PIN. Conductivity measurements investigated by universal power law indicated that the charge transport mechanism of all the samples is consistent with correlated barrier hopping model. POLYM. COMPOS., 37:3057–3065, 2016. © 2015 Society of Plastics Engineers     

Chitosan–poly(aminopropyl/phenylsilsesquioxane) hybrid nanocomposite membranes for antibacterial and drug delivery applications

We fabricated hybrid (CSSQ) membranes from chitosan and poly(aminopropyl/phenylsilsesquioxane) (PAPSQ) blends via a sol–gel reaction and solution casting followed by crosslinking with glutaraldehyde. The CSSQ membranes were then used for loading of 5‐fluorouracil (5‐FU) as an anticancer drug as well as templates for the production of silver nanoparticles (AgNPs). The physicochemical properties of the CSSQ membranes were examined using UV‐visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis and scanning electron microscopy (SEM). SEM results showed the controllable formation of AgNPs around PAPSQ. CSSQ–Ag nanocomposite membranes exhibited good antibacterial activity towards both Escherichia coli and Bacillus subtilis, while the CSSQ membranes worked as good carriers for controlled release of 5‐FU as model drug. The results suggest that both CSSQ and CSSQ–Ag nanocomposite membranes can be potentially applied for biomedical applications such as controlled release carriers as well as antibacterial wound dressing materials. © 2014 Society of Chemical Industry     

Mn‐Loaded Mesoporous Silica Nanocomposite: A Highly Efficient Humidity Sensor

We report a relative humidity sensor based on manganese‐nanoparticle‐loaded mesoporous silica SBA‐15 using a facile hydrothermal route. The as‐developed nanocomposite material (Mn/SBA‐15) possesses a high surface area and a high pore volume. The obtained samples were characterized by using low‐angle X‐ray Diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), N₂ adsorption–desorption, high‐resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and energy‐dispersive X‐ray (EDX) spectroscopy techniques. The Mn/SBA‐15 exhibited, improved humidity response and recovery time as compared to pure SBA‐15 in the 11%–92% RH range. Optimal results were obtained for the 5 wt% Mn‐loaded SBA‐15 sample, which displayed excellent linearity, low hysteresis, and high humidity response. A change in ~5 orders of magnitude in resistance was observed over 11%–92% RH range. The investigation of humidity sensing properties of Mn/SBA‐15 nanocomposite shows that this material has good prospects as humidity sensor.