Synthesis by in situ chemical oxidative polymerization and characterization of polyaniline/iron oxide nanoparticle composite

Polyaniline (PANI) is a well‐studied material and is the pre‐eminent electrically conducting organic polymer with the potential for a variety of applications such as in batteries, microelectronics displays, antistatic coatings, electromagnetic shielding materials, sensors and actuators. Its good environmental as well as thermal stability and electrical conductivity tunable by appropriate doping make PANI an ideal active material for several applications. In this paper, we report the synthesis of water‐dispersible colloidal PANI/iron oxide composite nanoparticles using an in situ chemical oxidation polymerization method in a micellar medium of sodium dodecylsulfate, where the cores (iron oxide) are embedded in a PANI matrix layer. Transmission electron micrographs showed evidence of the formation of an iron oxide core/PANI shell composite with a thin layer of PANI over the iron oxide cores. The results of thermogravimetric, Fourier transform infrared and UV‐visible analysis indicated that the iron oxide nanoparticles could improve the composite thermal stability possibly due to the interaction between iron oxide particles and PANI backbone. We believe that the synthetic route described can also be adapted for the assembly of hierarchical structures of other metal oxides or hydroxides onto various cores. Copyright © 2010 Society of Chemical Industry     

Preparation and characterization of core‐shell polystyrene/polyaniline/Pd composites and their catalytic properties for the reduction of 4‐nitrophenol

Herein, polystyrene/polyaniline/Pd (PS/PANI/Pd) core‐shell composite catalysts were prepared by a facile swelling‐diffusion‐interfacial polymerization method. PS microparticles were firstly prepared by dispersion polymerization and were swollen by aniline monomer without any surface modification. H₂PdCl₄ acid was used as palladium precursor. The was adsorbed on the surface of aniline‐swollen PS microparticles because of the electrostatic attraction between and anilinium positive ions protonated by H⁺, which was diffused from the aniline‐swollen PS microparticles. Then HCl solution was added to control the diffusion rate of anilinium positive ions and ammonium persulfate (APS) was used to polymerize the anilinium ions to get PANI shell. Due to the redox activity between PANI and Pd ions, Pd nanoparticles can be in situ formed on the surfaces of PS. Therefore, the core‐shell PS/PANI/Pd composite catalysts were obtained. The morphology and structure of the obtained composites was characterized by TEM, FT‐IR and EDX. Results showed that the products presented excellent catalytic properties for the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol (4‐AP) in the presence of NaBH₄ by virtue of the interaction between Pd nanoparticles and conducive PANI shell. The catalytic reaction obeyed the pseudo‐first‐order reaction equations and the reaction rate constants were also calculated in this article. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44812.     

Polyaniline/silver nanocomposites synthesized via UV–Vis‐assisted aniline polymerization with a reversed micellar microemulsion system

Polyaniline (PANI)/silver (Ag) nanocomposites were successfully synthesized within a sodium dodecyl sulfate reverse micro‐emulsion system and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, ultraviolet spectrometry, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and electrochemical methods. The results show that the core‐shell nanoparticles of less than 100 nm may be synthesized with PANI as shell formed around a core of nanoparticle. PANI/Ag nanocomposite prepared by this method has better thermal stability, higher conductivity, and electrochemical performance. The maximum conductivity (95.5 S/cm) was obtained when W₀ (water‐oil ratio) is 22. Cyclic voltammograms results show that PANI/Ag prepared by this method has a high response current and large capacitance. Polarization results show that E_corr (174.1 mV) and I_corr (50.6 μA/cm²) are better than the results for PANI and for PANI/Ag prepared by micro‐emulsion method. PANI/Ag nanocomposites prepared by the current method have potential applications in electrode materials, capacitors, conductive adhesives, and anticorrosion materials. POLYM. COMPOS. 37:1064–1071, 2016. © 2014 Society of Plastics Engineers     

Core‐shell method of synthesis,characterizations, and ac conductivity studies of polyaniline/n‐TiO2 composites

Polyaniline/nano‐titanium dioxide composites (PANI/n‐TiO₂) were prepared using α‐dextrose as surfactant and ammonium per sulfate as oxidant. The PANI/n‐TiO₂ composite is characterized by Fourier transform infrared spectra and confirmed the presence of benzenoid and qunoide ring structures and also formation of free ions. The transmission electron microscopy study reveals that the size of TiO₂ is in the order of 7 nm where as the composite size is of the order of 13 nm; further, it is observed that the TiO₂ particles are intercalated to form a core shell of PANI. The X‐ray diffraction (XRD) studies show that the monoclinic structure of the composites. ac Conductivity, permittivity, and tangent loss studies on these samples suggest that these composites may be well suited for gas sensor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of polyaniline/MCM‐41 composite through surface polymerization of aniline

Polyaniline (PANI)/porous silica MCM‐41 (MCM‐41) composite was synthesized according to surface polymerization theory, and it was confirmed through comparing with PANI/solid silica (SiO₂) by TGA and XPS techniques. The morphology and composition of the composite were also characterized by some techniques such as small‐angle XRD, N₂‐adsorption isotherm, SEM, FTIR, and UV–vis. The thermal stability for the PANI/MCM‐41 composite was enhanced when compared with that of pure PANI. With the increase in the concentration of HCl, the doping degree increased and UV‐absorption peak at about 700 nm showed a red shift. The conductivity of the composite was enhanced by increasing the concentration of HCl. The results of FTIR showed that there was a strong interaction between PANI and MCM‐41. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2088–2094, 2006     

Synthesis of processible doped polyaniline‐polyacrylic acid composites

Processible composites of emeraldine salt form of polyaniline (PANI) with polyacrylic acid (PAA) are synthesized and studied for their structural, electrical, mechanical, thermal, and electrochemical properties. The processible conducting composites of various weight percentage from 20 wt % to 90 wt % (of PANI) have been prepared by mixing the PANI and PAA under vigorous stirring and sonication conditions. Self‐standing films of electroactive homogeneous composites are obtained by solution casting method. A significant improvement in processibility, crystallinity, and thermal stability is observed in the composites; however, the electrical conductivity decreased remarkably as the percentage of PANI is decreased in the composites. The 60 wt % PANI‐PAA composite showed crystalline structural property with orthorhombic crystal system and cell parameters as a = 5.93Å, b = 7.57Å, and c = 10.11Å. The 60 wt % PANI‐PAA composite also showed better thermal stability and highest capacitance amongst all the composites and used as an active material for development of electrochemical capacitors (parallel plate assembly). The processible composites based electrochemical capacitors using 0.5 M NaClO₄‐Acetonitril electrolyte showed super capacitance with ease in fabrication and cost effectiveness in comparison to other similar materials based capacitors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Stability of polyaniline synthesized by a doping–dedoping–redoping method

Stability, including thermal stability, conductivity stability in air and after thermal treatment (100–200°C), of the polyaniline (PANI) films synthesized by a doping–dedoping–redoping method was investigated. It was found that thermogravimetric analysis (TGA) curves undergo three steps: loss of water or solvent, dedoping and decomposition, and those depend on the counterions. Compared with PANI films doped with camphor sulfonic acid (CSA) in m‐cresol, the thermal stability of the doped PANI films is improved by the new method, and thermal stability in the order of PANI–H₃PO₄ > PANI–p‐TSA > PANI–H₂SO₄ > PANI–HCl, PANI–HClO₄ > PANI–CSA was observed. The conductivity of the doped PANI films at room temperature was reduced after thermal treatment, and it is dependent of the counterions. It was found that the conductivity stability of PANI–p‐TSA and PANI–CSA is the best below 200°C. When the doped PANI films were placed in air, their conductivity decrease slowly with time due to deproton, and also depends on the counterions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 615–621, 1999     

Preparation of Cinnamon Oil‐Loaded Antibacterial Composite Microcapsules by In Situ Polymerization of Pickering Emulsion Templates

In this study, the cinnamon oil (CMO)‐loaded antibacterial composite microcapsules with silicon dioxide (SiO₂)/poly(melamine formaldehyde) (PMF) hybrid shells are effectively and facilely constructed by in situ polymerization of SiO₂ nanoparticle–stabilized Pickering emulsion templates. The morphological structure, composition, and thermal performance of the microcapsules are determined by scanning electronic microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. In addition, in vitro CMO release and antimicrobial investigations of the microcapsules are also performed, respectively. The results demonstrate that the microcapsules own an approximately spherical shape with a core–shell structure. Moreover, the micro‐encapsulation of CMO clearly increases its thermal stability, and meanwhile results in obtaining microcapsules with the controlled CMO release and visibly long‐term antimicrobial effects. All the results show that in situ polymerization based on templating Pickering emulsions is an attractive method to construct antibacterial essential oil–loaded microcapsules, which can be served as promising antibacterial materials.     

Improving photoluminescence of poly(9‐vinylcarbazole)/4,7‐diphenyl‐1,10‐phenanthroline/tris‐(8‐hydroxyquinoline) aluminum fibers via coaxial electrospinning

Solutions of poly(9‐vinylcarbazole)/4,7‐diphenyl‐1,10‐phenanthroline (PVK/Bphen) and poly(9‐vinylcarbazole)/tris‐(8‐hydroxyquinoline) aluminum (PVK/Alq₃) were individually delivered either to the inner or the outer needle of a coaxial spinneret for electrospinning to prepare green luminescent PVK/Bphen/Alq₃ composite fibers. The influence of both flow rate and applied voltage on the photoluminescence of the composite fibers was evaluated. Scanning electron microscopy showed ribbon‐like fibers with uneven surfaces and thickness of about 5 µm. Raman spectroscopy and fluorescence microscopy revealed that Bphen was homogenously dispersed in the PVK fibers; Alq₃ was not. Photoluminescence shows strong evidence that there are marked conditions where emission of the co‐electrospun PVK/Bphen/Alq₃ fibers significantly improved as compared with those produced by simple electrospinning. It is suggested that the enhanced dispersion of the Alq₃ allowed a more efficient energy transfer from the PVK to the Alq₃. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44019.     

Enhanced performance in organic light‐emitting diodes with copolymers containing both tris(8‐hydroxyquinoline) aluminum and 8‐hydroxyquinoline lithium groups

We synthesized novel copolymers containing both tris(8‐hydroxyquinoline) aluminum (Alq₃) and 8‐hydroxyquinoline lithium (Liq) groups as emitting layers for use in conventional two‐layer organic light‐emitting diodes. The network structure and thermal stability of these materials is described. The optical and electroluminescent properties of the copolymers were also studied. The performance optimization of the devices with the copolymers through the variation of the ratio of Alq₃ to Liq is described. A mechanism responsible for the improved electron injection is put forward. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4404–4410, 2006     

Design and preparation of low-filled magnetic oriented BN@Fe3O4/EP insulating composite with improved thermal conductivity and thermal stability

As an excellent two-dimensional insulating material with high thermal conductivity, high temperature stability and high hardness, hexagonal boron nitride(h-BN) is widely applied in semiconductor manufacturing, aerospace, metallurgical manufacturing and other cutting-edge fields. However, the unique surface structure of h-BN leads to poor lubricity and easy agglomeration, which limits the application of h-BN especially in the field of electronic packaging. To address key issues boosted above, this study designed and prepared the BN@Fe₃O₄ magnetic insulating particles and doped it into the reduced viscosity epoxy resin to prepare the composites. By selecting appropriate external magnetic field strength and BN@Fe₃O₄ particles’ content, a novel 3D structure of fillers like dominoes in epoxy resin composite was successfully constructed. The microstructure of the BN@Fe₃O₄ particles and composites were analyzed, the thermal conductivity, the mechanical and the electrical properties of composites were simultaneously tested. Results manifested that the core-shell structures with BN as core and Fe₃O₄ as shell was successfully prepared, linking through the PDA middle layer between the BN core and Fe₃O₄ shell. Under the influence of magnetic orientation, the BN@Fe₃O₄ magnetic particles were preferred an out-of-plane oriented in the epoxy resin composites, resulted an enormously enhanced on thermal conductivity of composites. At a magnetic field strength of 60 mT and 25 vol% BN@Fe₃O₄ content, the thermal conductivity of BN@Fe₃O₄/EP composites is as lofty as 1.832 W/(m K), which is 1023.46% higher than that of pure epoxy resin. Meanwhile, the thermal stability has also been slightly improved, the elastic modulus and insulation performances remain at the same level.     

Preparation of core–shell structured alumina–polyaniline particles and their application for corrosion protection

Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline (ANI) in the presence of alumina (Al₂O₃) particles. The polymerization of ANI occurred preferentially on the surfaces of the particles, resulting core–shell structured alumina–polyaniline (Al₂O₃‐PANI) particles. Morphology examination showed that with decreasing of the weight ratio of Al₂O₃/ANI in the reactants, the thickness of the PANI layer increased and changed from an even surface morphology to a particulate morphology. UV–vis and Fourier transformed infrared (FTIR) spectra indicated that there is no chemical interaction between the PANI layer and the Al₂O₃ surfaces. The PANI layer adhered well to the particles and can be used as anticorrosive fillers for polymer coatings. Enhanced corrosion protection performance was achieved for the emeraldine base (EB) form of PANI deposited Al₂O₃ particles (Al₂O₃‐EB) filled epoxy coating on carbon steel in 3.0 wt % aqueous NaCl solution. The particles demonstrate both excellent corrosion protection performance and lower cost, which will be of great importance in practical applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4372–4377, 2006     

Reactive flame retardant with core‐shell structure and its flame retardancy in rigid polyurethane foam

With a shell of poly (methyl methacrylate‐co‐hydroxyl ethyl acrylate) (PMMA‐HA), microencapsulated ammonium polyphosphate (MHAPP) is prepared by in situ polymerization. The core‐shell structure of the reactive flame retardant (FR) is characterized by Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The results of water leaching rate and water contact angle measurements show that ammonium polyphosphate (APP) is well coated by a hydrophobic shell. Due to the presence of active groups (–OH) and hydrophobic groups (–CH₃) in shell, MHAPP exhibits better compatibility, flame retardancy, and water resistance compared with neat ammonium polyphosphate (APP) in rigid polyurethane foam (PU). Compression strength of PU/MHAPP with suitable loading is higher than that of PU/APP and PU, the reason is that the active groups in shell can improve the compatibility of MHAPP in PU composite. From thermal stability and residue analysis, it can be seen that the presence of reactive flame retardant shows positive effect on thermal stability of PU composite at high temperature, results also indicate that MHAPP can promote the carbonization formation efficiency of PU composite during combustion process compared with APP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42800.     

Polyaniline–maleicacid–dodecylhydrogensulfate salt as sensor material for toxic gases

This article reports the results of novel polyaniline material as gas sensor, capable of operating at room temperature for toxic gases. Polyaniline–maleicacid–dodecylhydrogensulfate salt (PANI‐MA‐DHS) was prepared by emulsion polymerization pathway, which is soluble in N, N‐dimethyl formamide. PANI‐MA‐DHS was coated on a ceramic bead by simple brush coating method and used as sensor material. The resistance change of PANI‐MA‐DHS material for NH₃, CO₂, SO₂, and H₂S gases at different concentrations (10, 100, 1000, and 10,000 ppm level) was monitored for sensor characteristics. The stability of the polyaniline material under continuous exposure of gas level from 10 to 10,000 ppm was also studied. This novel gas sensor material has advantages such as excellent sensing ability, low cost, fast regeneration time (～ 1–2 min), simple experimental setup, and operable at room temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of core–shell nanocomposites with enhanced photocatalytic efficacy

The current study establishes the unprecedented involvement in the evolution and production of novel core–shell nanocomposites composed of nanosized titanium dioxide and aniline‐o‐phenylenediamine copolymer. TiO₂@copoly(aniline and o‐phenylenediamine) (TiO₂@PANI‐o‐PDA) core–shell nanocomposites were chemically synthesized in a molar ratio of 5:1 of the particular monomers and several weights of nano‐TiO₂ via oxidative copolymerization. The construction of the TiO₂@PANI‐o‐PDA core–shell nanocomposites was ascertained from Fourier transform IR spectroscopy, UV–visible spectroscopy and XRD. A reasonable thermal behavior for the original copolymer and the TiO₂@PANI‐o‐PDA core–shell nanocomposites was investigated. The bare PANI‐o‐PDA copolymer was thermally less stable than the TiO₂@PANI‐o‐PDA nanocomposites. The core–shell feature of the nanocomposites was found to have core and shell sizes of 17 nm and 19–26 nm, respectively. In addition, it was found that the addition of a high ratio of TiO₂ nanoparticles increases the electrical conductivity and consequently lowers the electrical resistivity of the TiO₂@PANI‐o‐PDA core–shell nanocomposites. The hybrid photocatalysts exhibit a dramatic photocatalytic efficacy of methylene blue degradation under solar light irradiation. A plausible interpretation of the photocatalytic degradation results of methylene blue is also demonstrated. Our setup introduces a facile, inexpensive, unique and efficient technique for developing new core–shell nanomaterials with various required functionalities and colloidal stabilities. © 2018 Society of Chemical Industry     

Magnetic and conducting Fe3O4–polypyrrole nanoparticles with core‐shell structure

Magnetic and conducting Fe₃O₄–polypyrrole nanoparticles with core‐shell structure were prepared in the presence of Fe₃O₄ magnetic fluid in aqueous solution containing sodium dodecylbenzenesulfonate (NaDS) as a surfactant and dopant. Both the conductivity and magnetization of the composites depend strongly on the Fe₃O₄ content and the doping degree. With increase of Fe₃O₄ content in the composite, the conductivity at room temperature decreases, but the saturated magnetization and coercive force increase. Transmission electron microscopy (TEM) images of Fe₃O₄ and Fe₃O₄–polypyrrole particles show almost spherical particles with diameters ranging from 20 to 30 and 30 to 40 nm, respectively. The thermal stability of Fe₃O₄–polypyrrole composites is higher than that of pure polypyrrole. Studies of IR, UV–visible and X‐ray photoelectron spectroscopy (XPS) spectra suggest that the increased thermal stability may be due to interactions between Fe₃O₄ particles and polypyrrole backbone. Copyright © 2003 Society of Chemical Industry     

Electrosynthesis and capacitive performance of polyaniline–polypyrrole composite

The composite of polyaniline and polypyrrole (PPY‐PANI) was prepared by two‐step electrochemical polymerization method. Techniques of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravity analysis (TG/DTG) measurements were used to characterize the morphology and structure of the composite. The electrochemical properties of the composite were investigated by cyclic voltammetry (CV), galvanostatic charge‐discharge, and electrochemical impedance spectroscopy (EIS). The results indicated that the polyaniline–polypyrrole composite showed better electrochemical capacitive performance than polypyrrole (PPY) and polyaniline (PANI). The specific capacitance of the composite electrode was 523 F/g at a current of 6 mA/cm² in 0.5 M H₂SO₄ electrolyte. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Preparation of high‐k composites with low dielectric loss based on the double‐layer coaxial structure of inorganic/polymer

This study presents a novel and simple modification of cladding multiwalled carbon nanotubes (MWCNTs) using organic polymer and inorganic nanoparticles to synthesize a product, which has a double‐cladding coaxial structure and can be applied as filler in the dielectric field. The first layer of MWCNTs was coated with polyaniline (PANI) through the oxidation–reduction reaction mechanism using Ce(NH₄)₂(NO₃)₆ as oxidizing agent and metal precursor of cerium oxide. Cerium ions on the second cladding layer of MWCNTs were directly deposited from the solution to the surface of the PANI layer forming the double‐cladding hybrid (CeO₂/PANI@MWCNTs). The external inorganic layer provides an insulating shell, which can prevent the contact between the conductive particles and hinder the migration of electrons between the MWCNTs. The intermediate layer of PANI provides the bonding between CeO₂ and the conductive core of MWCNTs, which also shows lower conductivity than carbon nanotubes. The CeO₂/PANI@MWCNTs were compounded with epoxy (EP) resin and formed a dielectric material with the advantage of reducing dielectric loss while ensuring high dielectric constant. The dielectric constant of the coated MWCNTs/EP composites was 194.90 at 10³ Hz with the content of fillers reaching 30 wt %, which is 28 times that of the pure EP. Accordingly, the dielectric loss of 30 wt % coated MWCNTs/EP composites was only 0.09 at 10³ Hz, which is only 2.25 times that of the pure EP. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46299.     

The interfacial effect of TiO2–Ag core–shell micro‐/nanowires on poly(arylene ether nitrile)

Novel TiO₂–Ag core–shell micro‐/nanowires (TiO₂ shell coating on Ag core) have been successfully prepared via a solvent–thermal method. Energy dispersive spectroscopy and X‐ray diffraction analyses revealed that the micro‐/nanowires were composed of Ag, Ti and O elements, and Ag was face‐centered cubic whereas TiO₂ was mainly amorphous. Interestingly, scanning electron microscopy (SEM) and transmission electron microscopy results showed that most of the TiO₂ bristles were perpendicular to and uniformly studded on the surface of the Ag cores. Subsequently, TiO₂–Ag/poly(arylene ether nitrile) (PEN) composite films were prepared via a solution‐casting method in order to investigate the effect of TiO₂–Ag on the PEN matrix. SEM images showed that there was good interfacial adhesion between fillers and PEN matrix owing to the special bristle‐like structure. Thermal analysis results showed that the TiO₂–Ag/PEN composite films possessed excellent thermal properties endowed by the PEN matrix. The dielectric constant of the composite films increased to 9.3 at 100 Hz when the TiO₂–Ag loading reached 40 wt%. Rheology measurements revealed that the network formed by TiO₂–Ag was sensitive to shear stress and nearly time independent. © 2013 Society of Chemical Industry     

The microencapsulation of calcium chloride hexahydrate as a phase‐change material by using the hybrid coupler of organoalkoxysilanes

A novel method of microencapsulation for inorganic salt hydrates as phase‐change material (PCM), which is essential for their broad application, was pursued by combining sol–gel process with interfacial polymerization. Calcium chloride hexahydrate (CCH), chosen as a representative PCM of salt hydrates, was used as a core material, and organoalkoxysilane was applied to provide hybrid properties of mediating the hydrophilic core and hydrophobic shell material. The Fourier transform infrared spectra and SEM images confirmed that the siloxane and polyurea shell material successfully capsulated the CCH core. Fine morphology of microcapsules was further investigated with SEM, and it presented almost‐spherical shape and a well‐defined core–shell structure. Thermogravimetric analysis indicated that microcapsules containing CCH have sufficient thermal stability, which usually degraded in four steps. Differential scanning calorimeter investigation confirmed additionally that the microencapsulated CCH absorbs thermal energy with phase change during the melt process but undergo a severe super cooling phenomenon in the crystallizing process. In addition, the durability test was conducted to evaluate the siloxane polymer and polyurea as a shell material, protecting CCH from leaking. The effect of pH and the ratio of ingredients were studied in terms of encapsulation possibility and performance of core PCM, which include morphology of core–shell particles and essential thermal properties as a PCM. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45821.