Enhanced dielectric and electrorheological properties of needle‐like TiO2/polyrhodanine core/shell hybrid nanostructure

In this study, antisedimentation, dielectric, electrorheological (ER) and creep–recovery properties of needle‐like TiO₂/polyrhodanine (PRh) nanocomposite were investigated. Antisedimentation ratio of needle‐like TiO₂/PRh was determined to be 45% after 30 days in silicone oil (SO). Polarizability and relaxation time of needle‐like TiO₂/PRh/SO system were determined to be 0.18 and 2.9 × 10^?5 s, respectively by the dielectric spectroscopy which was further used to evaluate the ER performance of the dispersion, and the data obtained were in good agreement with the overall ER results. ER properties of needle‐like TiO₂/PRh/SO system were determined by taking the effects of shear rate, shear stress, electric field strength, and temperature into account using a torque electrorheometer. Non‐Newtonian shear thinning behaviors were observed for the samples. Vibration damping capabilities of the dispersions were investigated by measuring their elastic and viscous moduli as functions of frequency, time, and electric field strengths. Enhanced and reversible viscoelastic deformations were recorded for needle‐like TiO₂/SO system from creep–recovery tests with 88% recovery under E = 3.5 kV mm^?1 condition; thus, the system was classified as a smart one and suitable for potential vibration damping applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43240.     

Ag/polyaniline nanocomposites: Synthesize,characterization, and application to the detection of dopamine and tyrosine

In this research, Ag/Polyaniline (PANI) nanocomposites were synthesized successfully by the chemical oxidative polymerization of aniline in the presence of 4‐aminothiophenol (4‐ATP) capped colloidal Ag nanoparticles (NPs). First, Ag colloidal NPs were prepared by borohydride reduction of AgNO₃ in the presence of 4‐ATP as a stabilizer. Then, polymerization of aniline in the presence of Ag NPs was carried out by ammonium persulfate as an oxidant at room temperature. TEM, SEM, XRD, FTIR, EDX, TGA, and UV–vis studies were done for the morphological, structural, thermal, and optical characterization of the Ag/PANI nanocomposite. Furthermore, Ag/PANI nanocomposites were immobilized on the surface of a glassy carbon electrode (GCE) and electroactivity behavior was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained Ag/PANI modified GCE showed high catalytic activity for the oxidation of dopamine (DA) and tyrosine (Tyr). The peak current of differential pulse voltammograms of DA and Tyr increased linearly with their concentration in the ranges of 2.17–5.74 μM Tyr and 18.5–72.2 μM DA. The detection limits for DA and Tyr were 0.002 and 0.009 μM, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2780–2789, 2013     

Polypyrrole‐wrapped Pd nanoparticles hollow capsules as a catalyst for reduction of 4‐nitroaniline

In this study, by in situ reduction of Pd²⁺ ions attached on the surface of the sulfonated polystyrene (PS‐SO₃H) spheres, complete and dense palladium (Pd) nanoparticles (NPs) layer were deposited around PS‐SO₃H spheres. The PS@Pd spheres were wrapped by polypyrrole (PPy) shell, which could avoid escaping of Pd NPs. After selectively etching the PS core, the hollow structures with Pd NPs embedded in PPy capsule shell were obtained. The as‐prepared Pd@PPy hollow capsules showed excellent catalytic activity toward the reduction of 4‐nitroaniline because of the high Pd NPs loading. Furthermore, good reusabilty was demonstrated seven times without any detectible loss in activity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43933.     

Nanostructured star‐shaped polythiophene with tannic acid core: Synthesis,characterization, and its physicochemical properties

For the first time, synthesis and characterization of a nanostructured star‐shaped polythiophene (PTh) with tannic acid core by both chemical and electrochemical oxidation polymerization methods through a “core‐first” method is reported. The chemical structures of all samples as representatives were characterized by means of Fourier transform infrared (FTIR), and ¹H nuclear magnetic resonance (NMR) spectroscopies. The electroactivity behaviors of the synthesized samples were verified under cyclic voltammetric conditions, and their conductivities were determined using the four‐probe technique. The synthesized star‐shaped PTh showed higher electrical conductivity and electroactivity than those of the PTh in both chemical and electrochemical polymerized samples, due to its large surface area, spherical, and three‐dimensional structure. Moreover, the thermal behaviors, optical properties, and morphologies of the synthesized samples were investigated by means of thermogravimetric analysis (TGA), ultraviolet–visible (UV–Vis) spectroscopy, and field emission scanning electron microscopy (FE‐SEM), respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43513.     

A simple one‐step chemical route to gold/polymer core/shell composites and polymer hollow spheres

Au/poly(o‐toluidine) (POT) core/shell composite spheres have been successfully fabricated by chemical polymerization route in aqueous solution without the aid of surfactant or functional acids using HAuCl₄ as the oxidant. By altering the concentration of oxidant, the amount of Au nanoparticles inside each POT sphere can be tuned from tens to one. Moreover, uniform POT hollow spheres with one opening in each polymer surface can be obtained under extremely low concentration of oxidant. The chemical structures of Au/POT composites were confirmed by Fourier transform infrared (FTIR), UV‐vis, and X‐ray diffraction (XRD) spectroscopies. Moreover, the formation mechanisms of Au/POT core/shell composites and POT hollow spheres were also discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The electrorheological properties of polyaniline nanofiber/kaolinite hybrid nanocomposite

A novel polyaniline nanofiber/kaolinite nanoplatelet hybrid nanocomposite was synthesized by means of rapidly mixed in situ polymerization. The resultant polyaniline/kaolinite hybrid nanocomposite was characterized via different techniques, such as X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that 2D clay nanoplatelets are coated by the 1D polyaniline nanofibers. The nanoclay platelets can improve the thermal stability of polyaniline nanofibers. An electrorheological effect is found with the suspension of polyaniline nanofiber/kaolinite nanoplatelet hybrid nanocomposite dispersed in silicone oil. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1104‐1113, 2013     

Chemical preparation of conducting polyfuran/poly(2‐chloroaniline) composites and their properties: A comparison of their components,polyfuran and poly(2‐chloroaniline)

Conductive homopolymers and composites of poly(2‐chloroaniline) (P2ClAn) and polyfuran (PFu) were synthesized chemically in hydrous and anhydrous media, and their properties were investigated. The polymers and composites were characterized by Fourier infrared spectroscopy, ultraviolet‐visible absorption spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, magnetic susceptibility, and conductivity measurements. It was found that the PFu/P2ClAn composite is thermally more stable than both the P2ClAn/PFu composite and the homopolymers. It was determined from Gouy scale measurements that conducting mechanisms of homopolymers and composites are polaron and bipolaron in nature. It was observed that the conductivity and magnetic susceptibility values changed with a changing amount of the guest polymer in the prepared composites. The conductivity (3.21 × 10^?2 S/cm) of the P2ClAn/PFu (55.8% m/m) composite was found to be higher than the conductivities of both homopolymers (σ_PFu = 1.44 × 10^?5 S/cm; σ_P2ClAn = 1.32 × 10^?3 S/cm). It was determined that the composites synthesized had different conductivities and morphological and thermal properties from changing synthesis order. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2924–2931, 2003     

Low dielectric and high thermal conductivity epoxy nanocomposites filled with NH2‐POSS/n‐BN hybrid fillers

Hybrid fillers of mono‐amine polyhedral oligomeric silsesquioxane/nanosized boron nitride (NH₂‐POSS/n‐BN) were performed to fabricate NH₂‐POSS/n‐BN/epoxy nanocomposites. Results revealed that the dielectric constant and dielectric loss values were decreased with the increasing addition of NH₂‐POSS obviously, but increased with the increasing addition of BN fillers. For a given loading of NH₂‐POSS (5 wt %), the thermal conductivities of NH₂‐POSS/n‐BN/epoxy nanocomposites were improved with the increasing addition of n‐BN fillers, and the thermal conductivity of the nanocomposites was 1.28 W/mK with 20 wt % n‐BN fillers. Meantime, the thermal stability of the NH₂‐POSS/n‐BN/epoxy nanocomposites was also increased with the increasing addition of n‐BN fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41951.     

Polyaniline nanofibers for In situ MAO‐catalyzed polymerization of ethylene

In this work electro‐conductive polyaniline nanofibers (PAni‐nanofibers) were prepared via interfacial methodology. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the synthesized PAni‐nanofibers present high aspect ratio with an average diameter of 80 nm, while they exhibit high conductivity (DC conductivity values: 4.19 ± 0.21 S cm^?1). After specific treatment to remove moisture and remaining trapped HCl from PAni‐nanofibers, it was possible to prepare promising polyethylene (PE)/PAni composites by in situ polymerization of ethylene using bis(cyclopentadienyl) zirconium(IV) dichloride (Cp₂ZrCl₂) and methylaluminoxane (MAO) as catalytic system. More precisely, various contents of PAni‐nanofibers (from 0.2 to 7 wt %) were successfully incorporated in the in situ produced PE/PAni nanocomposites. PAni‐nanofibers were found to affect significantly the crystallization of the polyolefinic matrix while preserving its thermal stability. Preliminary measurements of electric properties showed PAni‐nanofibres are able to bring electro‐conductive properties to the in situ polymerized PE/PAni composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41197.     

Synthesis and characterization of a conducting polyaniline/TiO2−SiO2 composites

Polyaniline/TiO₂?SiO₂ composites were prepared by an in situ chemical oxidation polymerization approach in the presence of hybrid TiO₂?SiO₂ fillers. The obtained polyaniline/TiO₂?SiO₂ composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), thermogravimetry (TG), and current?voltage (I?V) measurements. SEM picture shows a variation in morphology of polyaniline (PANI) from fiber shape to relatively regular particle shape with increasing TiO₂?SiO₂ contents in the composites. The floccule‐like structures were observed by high resolution TEM, which may help improve the efficiency of conductive network. SEM, XRD, TG, and FTIR spectra all reveal that a relatively strong interaction exist between TiO₂?SiO₂ and PANI. The I?V characteristics in such composites indicate that the charge transport is mainly governed by the space charge effects, which occurs at the interface between the conducting PANI and TiO₂?SiO₂. Meanwhile, PANI/TiO₂?SiO₂ composites exhibit significant increase in conductivity than PANI/TiO₂ or PANI/SiO₂. The reasons about high conductivity of PANI/TiO₂?SiO₂ have also been discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2288–2295, 2013     

A method for scale‐up of co‐electrospun nanofibers via flat core‐shell structure spinneret

An approach to the scale‐up of co‐electrospinning via a flat core‐shell structure spinneret has been developed in this study. The spinneret with a flat surface involves shell‐holes and core‐needles. Electric field simulation reveals that the flat core‐shell spinneret configuration creates a more uniform electric field gradient. Experimental study shows that in comparison with the conventional needle co‐electrospinning, core‐shell nanofibers produced by this new designed setup are finer and of better morphology. Composite nanofibers with special morphologies can be fabricated by modifying the structure of this spinneret. The production rate of the core‐shell nanofibers can be enhanced by increasing the hole and needle number of the spinneret. This novel design is expected to provide a promising method towards the massive production of core‐shell nanofibers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41027.     

Effect of CuBr2 salt treatment on the performance of nanocolloidal PPy:PSS multilayer thin film counter electrodes of dye‐sensitized solar cells

A thin Pt layer on fluorine‐doped tin oxide (FTO) glass is commonly used as the counter electrode (CE) for dye‐sensitized solar cells (DSCs). We have investigated thin layers on FTO glass made from spherical polypyrrole (PPy)–poly(styrene sulfonate) (PSS) nanocolloidal particles with and without treatment of CuBr₂ and used them as CEs. The colloidal polymer composite (PPy:PSS) was spin‐coated at 4000 rpm, and PPy:PSS multilayer (one, three, five) films were employed as the CEs. Aqueous solutions of CuBr₂ (0.5 M and 1 M) were coated onto the multilayer CEs, which increased the efficiency of DSCs. When compared with the untreated PPy:PSS counter electrodes, the CuBr₂‐treated PPy:PSS films showed lower charge‐transfer resistance, higher surface roughness, and improved catalytic performance for the reduction of . The enhanced catalytic performance is attributed to the interaction of the superior electrocatalytic activity of PPy:PSS and CuBr₂ salt. Under standard AM 1.5 sunlight illumination, the counter electrodes based on a single‐layer PPy:PSS composite with 0.5 M and 1 M CuBr₂ salt treatment demonstrated power conversion efficiencies (PCE) of 5.8% and 5.6%, respectively. These values are significantly higher than that of the untreated PPy:PSS CE and are comparable with that of a Pt CE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43772.     

Polyaniline self‐assembled with DTPA: Facilely tuned morphology and properties

The effects of pH profile and “soft template” during aniline chemical oxidative polymerization (COP) were investigated and evaluated simultaneously with diethylene triamine pentaacetic acid (DTPA) as a structural directing agent. Formation of PANI nanotubes and nanoparticles, smooth microspheres, and urchin‐like microspheres were illustrated by evaluating the pH profile during aniline COP while considering the “soft template” effects of DTPA. PANI nanosheets with two semicurled edges were found in the system producing nanotubes, which provides an evidence for the “curling mechanism” of PANI nanotube formation. With different pH profiles, chemical structures and aggregation structures of the as‐synthesized PANI micro/nanostructures are similar, whereas their conductivity, wettability, Cr (VI) adsorption, and electrochemical behaviors are distinct. The present study indicates that if properly conducted, pH profile adjustment is more effective than “soft template” to control the morphology and to optimize the performance of PANI micro/nanostructures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42403.     

Enhancing the electrical conductivity of carbon black/graphite nanoplatelets: Poly(ethylene‐butyl acrylate) composites by melt extrusion

The influence of processing parameters such as screw geometry, temperature profile, and screw speed on the electrical properties of hybrid composites consisting of graphite nanoplatelets and carbon black in ethyl butyl acrylate was studied. Two different screws were used to compound the hybrid composites at two different temperatures and two different screw speeds. A beneficial effect was noted with regard to the electrical properties when adding nanoplatelets to the filler system. The cause could be a synergistic effect due to the difference in particle shape of the two fillers. Lower percolation thresholds were obtained with the conventional screw due to less breakage of the graphite nanoplatelets compared to the barrier screw. No significant changes of the electrical properties were observed when changing the temperature profiles or the screw speeds. Furthermore, the melt viscosity of the compounds was not appreciably affected at the rather low filler contents used here. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42897.     

Fabrication of PFO‐DBT:OXCBA nanostructured composite via hard template

Poly[2,7‐(9,9‐dioctylfluorene)‐alt−4,7‐bis(thiophen‐2‐yl)benzo‐2,1,3‐thiadiazole] (PFO‐DBT) and o‐xylenyl‐C₆₀‐bisadduct (OXCBA) nanostructured composite has been fabricated via the hard porous alumina template‐directed method. Spin‐coating technique at the spin rate of 1000 rpm is used to assist the infiltration of polymer solution into porous template. PFO‐DBT nanotube is fabricated by replicating the porous alumina template before the formation of PFO‐DBT:OXCBA nanostructured composite. Formation of nanostructured composite is completed once the infiltration of OXCBA solution into PFO‐DBT nanotubes is achieved. Detailed results of morphological, structural, and optical properties of PFO‐DBT nanostructures (nanorods and nanotubes) of different solution concentrations are reported. By tuning the optical properties of PFO‐DBT nanostructures, the effect of solution concentration on the optical properties can be realized. The promising PFO‐DBT nanotubes are chosen for the further fabrication of OXCBA:PFO‐DBT nanostructured composite that acts as a core and shell, respectively. Although the nanostructured composite of PFO‐DBT:OXCBA yield low light absorption intensity, the absorption spans the whole visible region and produce low optical energy gap. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44228.     

Synchronization of thermal properties and constituents in Nanocomposite: Manufacturing,characterization, adjustable properties

This is critical to maintain better thermal properties, especially thermal conductivity as well as low particle content along with organized particle dispersion in polymer nanocomposites. Thus, this study is designed to develop a nanocomposite containing a constant reinforcing load of binary particles (carbon and alumina) in the binary matrix of polypropylene (PP)/poly ethylene-co-vinyl acetate (EVA). The samples were prepared through the melt blending and hot pressing technique. Compared to pure PP/EVA matrix, the nanocomposites showed a shift in Fourier-transform infrared spectroscopy peak and absorption intensity, which proves better interaction of nanoparticles with the matrix. The Scanning Electron Microscopy analysis showed the nanocomposite having carbon (C) and alumina (A) relative ratio 2:3 offered even structure with better distribution of nanoparticles compared to other nanocomposites. Also, Differential scanning calorimetry and Thermogravimetric analysis revealed that alumina-rich binary nanoparticles reinforced composites offer an efficient improvement in thermal behavior. Moreover, the nanocomposite containing high alumina relative ratio (C: A = 2:3) gives a sharp shift in thermal conductivity of 1.57 W/m-k from 1.2 W/m-k of carbon-rich nanocomposite (C: A = 3:2) and 0.16 W/m-k of pure PP/EVA. However, these relative properties emphasize the important role of this nanocomposite as a programmable thermal material.     

Self‐healing and interfacially toughened carbon fibre‐epoxy composites based on electrospun core–shell nanofibres

Dual components of a self‐healing epoxy system comprising a low viscosity epoxy resin, along with its amine based curing agent, were separately encapsulated in a polyacrylonitrile shell via coaxial electrospinning. These nanofiber layers were then incorporated between sheets of carbon fiber fabric during the wet layup process followed by vacuum‐assisted resin transfer molding to fabricate self‐healing carbon fiber composites. Mechanical analysis of the nanofiber toughened composites demonstrated an 11% improvement in tensile strength, 19% increase in short beam shear strength, 14% greater flexural strength, and a 4% gain in impact energy absorption compared to the control composite without nanofibers. Three point bending tests affirmed the spontaneous, room temperature healing characteristics of the nanofiber containing composites, with a 96% recovery in flexural strength observed 24 h after the initial bending fracture, and a 102% recovery recorded 24 h after the successive bending fracture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44956.     

Dulse‐derived porous carbon–polyaniline nanocomposite electrode for high‐performance supercapacitors

Dulse‐derived porous carbon (DDPC)–polyaniline (PANI) nanocomposites were fabricated by a method based on the in situ chemical oxidation polymerization of aniline on DDPC. The characterization of the material showed that the nano‐PANI was grown on the surface of DDPC in the form of nanosticks or nanoparticles. The DDPC–PANI nanocomposites were further used as electrode materials for energy‐storage applications. Meanwhile, the effect of the amount of aniline on the electrochemical performance of DDPC–PANI was also investigated. The results show that a maximum specific capacitance of 458 F/g was achieved for the DDPC–PANI nanocomposites; this was higher than that of the DDPC electrode (218 F/g), and the PANI electrode (318 F/g). The specific capacitance of DDPC–PANI remained 66.0% of the initial value after 5000 cycles; this was higher than that of PANI (50.5%). Finally, a device of DDPC–PANI–activated carbon (AC) was assembled with DDPC–PANI as a positive electrode, which exhibited a high energy density of 9.02 W h/kg, which was higher than that of PANI–AC device. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45776.     

Morphology controlled synthesis of polyaniline nanostructures using swollen liquid crystal templates

Preparation of zero‐dimensional and one‐dimensional nanostructures of polyaniline (PANI) were achieved by using swollen liquid crystals (SLCs) as ‘soft' templates. The monomer (aniline) was first entrapped in SLCs by replacing the oil phase (cyclohexane) with a mixture of aniline and cyclohexane. Zero‐dimensional nanostructures of PANI were obtained by thorough mixing of APS with the mesophases. One‐dimensional nanostructures were prepared by allowing slow diffusion of APS through the mesophase. PANI nanostructures were extracted from the mesophase and were characterized by UV‐visible spectroscopy, FTIR spectroscopy, powder X‐ray diffraction, atomic force microscopy, scanning electron microscopy (SEM), and conductivity measurements. A plausible mechanism for the formation of the nanostructures has been proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40800.     

Capacitance properties of graphite oxide/poly(3,4‐ethylene dioxythiophene) composites

Poly(3,4‐ethylene dioxythiophene) (PEDOT) and graphite oxide (GO)/PEDOT composites (GPTs) doped with poly(sodium styrene sulfate) (PSS) were synthesized by in situ polymerization in aqueous media. The electrochemical capacitance performances of GO, PEDOT–PSS, and GPTs as electrode materials were investigated. The GPTs had a higher specific capacitance of 108 F/g than either composite constituent (11 F/g for GO and 87 F/g for PEDOT–PSS); this was attributable to its high electrical conductivity and the layer‐within/on‐layer composite structure. Such an increase demonstrated that the synergistic combination of GO and PEDOT–PSS had advantages over the sum of the individual components. On the basis of cycle‐life tests, the capacitance retention of about 78% for the GPTs compared with that of 66% for PEDOT–PSS after 1200 cycles suggested a high cycle stability of the GPTs and its potential as an electrode material for supercapacitor applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011