Emulsion Polymerization Of Aniline Research Articles

Polyaniline-(dinonylnapthyl disulphonic acid) hydrogel showing enhanced supercapacitor and photo-current performance by in situ growth of AgNPs

Emulsion polymerization of aniline in presence of dinonylnapthyl disulphonic acid (DNNDSA) produces 3D-fibrillar network and invariant storage and loss modulus with frequency suggest (PANI-DNNDSA, PD) gel formation. The x-ray diffraction and x-ray photoelectron spectroscopy confirm in-situ Ag NP formation. The PD gel exhibits excellent specific capacitance of 1100 F/g, however, in-situ growth of AgNPs (PDAg1.2) exhibits specific capacitance 1350 F/g at 1 A/g current density in three-electrode technique. Two electrode measurement with flexible carbon cloth using poly(vinyl alcohol)-H2SO4 gel electrolyte shows a specific capacitance value of 646 F/g and Ragon plot exhibits maximum power density 7000 W/kg at energy density of 34.7 Wh/kg. The PDAg1.2 gel exhibit highly improved photocurrent with simultaneous presence of photocurrent memory and photocurrent rectification which are absent in pure PD gel. Due to synergistic interaction between silver plasmon bands and polaronic bands of PANI very good photocurrent and stable photocurrent switching is noticed.

Improving the Performance of PANI‐SA⋅TiO2Supercapacitor Active Electrode MaterialviaEmulsion Polymerization of Aniline with MWCNT

AbstractFlexible electrode with high electrical conductivity and electrochemical performance are desirable today to meet the energy demand in portable electronics. Here we designed a flexible electrode, polyaniline‐sulfate‐titanium dioxide‐multiwalled carbon nanotubes (PANI‐SA⋅TiO2⋅MWCNT) to improve the electrochemical performance. This is achieved by following a synthetic strategy via the synthesis of PANI‐SA⋅TiO2⋅MWCNT by a two‐step process; initially, PANI‐SA⋅TiO2synthesized by aqueous polymerization using two oxidants, namely peroxotitanium acid (PTiA) and ammonium persulfate (APS). Wherein, PTiA acts both as oxidant and source of TiO2. In the second step, emulsion polymerization of PANI‐SA⋅TiO2with a small amount of MWCNT by benzoyl peroxide as oxidant. Formed PANI‐SA⋅TiO2⋅MWCNT was coated on a stainless steel foil without using any binder. Electrochemical performances of the electrodes of both PANI‐SA⋅TiO2and PANI‐SA⋅TiO2⋅MWCNT were carried in symmetric cell supercapacitor configuration in aq. 1 M sulfuric acid electrolyte by cyclic voltammetry and charge‐discharge measurements. This composite exhibits an excellent rate capability, and no degradation was observed in specific capacitance over 5,000 charge‐discharge cycles carried even at a higher current density of 1.6 A g−1. The electrochemical performance of PANI‐SA⋅TiO2,including cycle life, is enhanced with the use of MWCNT.

Tollen’s reagent assisted synthesis of hollow polyaniline microsphere/Ag nanocomposite and its applications in sugar sensing and electromagnetic shielding

The present study is focused on synthesis of polyaniline hollow microspheres (PnHM) nanocomposites of silver (Ag) i.e., PnHMAg by emulsion polymerization of aniline and Tollen’s reagent as a source for Ag nanoparticles. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis of PnHMAg indicated presence of silver nanoparticles dispersed on polyaniline surface. The electrical conductivity of PnHMAg is increased by ∼6 times compared to PnHM. Cyclic voltammogram of PnHM in sugar sensing exhibits characteristics redox peaks at ∼0.09 (sugar) and ∼0.53V (polyaniline). Interestingly, PnHMAg showed a single peak at ∼−0.18V with increased intensity (∼5 times) indicating its high sugar sensing ability. PnHMAg also exhibits high shielding efficiency of 19.5dB (11.2GHz) due to the presence of highly conducting Ag nanoparticles. TEM studies confirmed that Ag nanoparticles are well distributed on PnHM. As a result, a continuous electronic path is developed due to enhanced interconnectivity of PnHM.

Conductive elastomeric nanocomposites based on oxidation of aniline with silver nitrate via inverse emulsion polymerization

The present investigation describes a facile and rapid approach of conductive nanocomposites production and assesses the opportunity of their use as electro-mechanical sensors. Hybrid materials containing silver and polyaniline nanoparticles reinforcing a thermoplastic elastomeric matrix were studied. The approach developed includes ultrasonically assisted in situ inverse emulsion polymerization of aniline oxidized by a weak oxidant and silver nitrate, and supported with a strong oxidant, ammonia peroxydisulfate. Aniline was doped with dodecylbenzene sulfonic acid in the presence of dissolved styrene–isoprene–styrene thermoplastic elastomer. While conventional polymerization of aniline with silver nitrate takes 2 weeks, by utilization of inverse emulsion polymerization, the reaction time reduces to 5 days. The assistance of a strong oxidant dramatically shortens the reaction time to 30 min. The technique developed results in uniform distribution of polyaniline/silver (PANI/Ag) conductive nanoparticles in the elastomeric matrix. The morphological studies of the films reveal spherically shaped 45 nm Ag particles. The presence of PANI/Ag in the styrene–isoprene–styrene elastomeric matrix enhances the electrical, thermal, and mechanical properties of the nanocomposites. The approach described provides an opportunity of the development of tunable structures and a remarkably distinctive architecture. A rapid electrical resistance response to an applied strain makes the nanocomposites developed useful as sensitive strain sensors. Copyright © 2014 John Wiley & Sons, Ltd.

Investigation of corrosion performance of epoxy coating containing polyaniline nanoparticles

An emulsion polymerization of aniline was performed in a solution of dodecylbenzenesulfonic acid emulsifier, benzoyl peroxide oxidant and tartaric acid as dopant. The polyaniline-containing coating was applied over carbon steel panels and the polyaniline content in the coating was 1 %. The influence of reactants concentration on the morphological and anti-corrosive properties of polyaniline was investigated to determine the optimum conditions for the synthesis of polyaniline nanoparticles. The average size of particles determined by X-ray diffraction measurement was 70–104 nm, which is found to be in agreement with the scanning electron microscopy results. Corrosion resistance of coatings was obtained using electrochemical techniques (electrochemical impedance spectroscopy and open circuit potential measurements) in 3.5 % sodium chloride solution. Nyquist diagrams showed two capacitance loops, one at high frequency range followed by a larger one at low frequencies due to coating and charge transfer resistance. The corrosion resistance values were found to decrease due to the corrosion of carbon steel in pinholes of the coating. For longer immersion times, the coating resistance values were found to increase due to the passivation effect of polyaniline. The results showed that epoxy coating with doped polyaniline nanoparticles is able to offer protection in sodium chloride solution.

Electrical properties of in situ polymerized polystyrene/polyaniline composites: The effect of feeding ratio

Polystyrene/polyaniline (PS/PANI) composites were prepared by emulsion polymerization of aniline in a mixture of PS and dichloromethane, at different feeding ratios of aniline to PS. Dodecylbenzenesulfonic acid (DBSA) was used as a dopant during chemical oxidation of aniline. Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), scanning and transmission electron microscopies (SEM and TEM) were used for structural characterization of the composites. The effect of PANI content on electrical properties of the composites was studied by electrical resistivity and electromagnetic interference (EMI) shielding measurements. Electron microscopy showed that the conductive PANI distributed in the continuous PS matrix, heterogeneously. Electrical conductivity, EMI shielding effectiveness, real permittivity and imaginary permittivity values increased with PANI content. It was found that absorption had more contribution to EMI shielding than reflection. 1.1mm thick samples of the composites exhibited electrical conductivity up to 10−2S/cm and electromagnetic interference shielding effectiveness (EMI SE) up to 8dB, for sample containing ca. 20wt% PANI.

Effect of reaction conditions on film morphology of polyaniline composite membranes for gas separation

AbstractComposite membranes combining polyaniline as an active layer with a polypropylene support have been prepared using an in situ deposition technique. The protonated polyaniline layer with a thickness in the range of 90–200 nm was prepared using precipitation, dispersion, or emulsion polymerization of aniline with simultaneous deposition on top of the porous polypropylene support, which was immersed in the reaction mixture. Variables such as temperature, concentration of reagents, presence of steric stabilizers, surfactants, and heteropolyacid were found to control both the formation and the quality of the polyaniline layers. Both morphology and thickness of the layers were characterized using scanning electron microscopy. Selective separation of carbon dioxide from its mixture with methane is used to illustrate potential application of these composite membranes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Preparation and Characterization of Polyaniline / Montmorillonite Composite by Situ Emulsion Polymerization

Polyaniline(PANI)/montmorillonite(MMT)composites were prepared by situ emulsion polymerization of aniline at 0 °C in the presence of MMT in aqueous solution with ammonium persulfate (APS) and dodecylbenzene sulfonic acid (DBSA) as oxidant and surfactant (acid dopant), respectively. Infrared spectra revealed the shift of N-B-N stretching vibration band, suggesting the presence of interfacial interactions between PANI chains and clay layers. X-ray diffraction showed an increase in the interlayer spacing from 1.26 nm for MMT to 1.468nm for PANI/MMT10%, signifying PANI was intercalated into the MMT galleries and the expansion is in agreement with the intercalation of single chains with extended chain conformation. Thermal gravimetric analysis suggested that the introduction of MMT clay resulted in improvement of thermal stability of the composites. It was found that when the MMT content reached a certain limit (30%), the PANI/MMT showed higher conductivity than pristine PANI .

A novel ternary composite: fabrication, performance and application of expanded graphite/polyaniline/CoFe2O4 ferrite

Expanded graphite–polyaniline microparticles (EG/PANI), synthesized by the emulsion polymerization of aniline in the presence of expanded graphite, were coated with CoFe2O4 ferrite (CF) to form ternary composites of EG/PANI/CoFe2O4 (EG/PANI/CF). The phase composition, morphology, electrical and magnetic performances of the composites were characterized by means of modern measurement technology. The results indicated that the electrical and magnetic performances of the ternary composites were related to their composition, and were better than those of binary composites. The EG/PANI/CF composites with a mCF/mEG/PANI of 0.2 had the best conductivity (86.207 S cm−1) of all ternary composites. The EG/PANI/CF composites with a mCF/mEG/PANI of 0.8 at a thickness of 0.5 mm had the minimum reflection loss of −19.13 dB at 13.28 GHz and an available bandwidth of 5.94 GHz. Hence, the obtained composites had potential and valuable applications in microwave shielding and absorption fields.

Probing the Molecular Interactions at the Conducting Polyaniline Nanomaterial Surface via a Pyrene Fluorophore

We report a unique fluorophore cumulant dopant approach for tracing the molecular interaction at the polyaniline nanomaterial surface. Emulsion polymerization of aniline + pyrene sulfonic acid (PSA) produced well-defined fluorescent polyaniline nanofibres of 250 nm diameters with lengths up to 1−3 μM. Post-polymerization doping of a polyaniline emerldine base with PSA produced fluorescent agglomerated nanospheres of 500−700 nm in diameter. Dynamic light scattering (DLS) analysis of the aniline + PSA complex confirmed the existence of ∼25 nm micellar aggregates in the emulsion which templates for the polyaniline nanofibers during the chemical oxidation process. The compositions of the dopant and polymer in the nanomaterials were determined by absorbance spectroscopy. The plots of incorporation of PSA in the nanomaterials versus feed revealed that the dopants incorporated a five times higher amount in the emulsion route compared to that of post-doping process. Wide angle X-ray diffraction (WXRD) analysis sh...

Expanded graphite/polyaniline electrical conducting composites: Synthesis, conductive and dielectric properties

Expanded graphite/polyaniline electrical conducting composites were prepared by emulsion polymerization of aniline in the presence of expanded graphite. The phase composition and morphology of the composites were characterized by X-ray diffractometer and scanning electron microscopy, respectively. The electrical conductivities were measured by a four-probe resistivity instrument. The dielectric loss factor was performed on an impedance/material analyzer. The electrical conductivities of the composites were enhanced dramatically to 298.51 S cm − 1 compared to polyaniline. The composites also showed excellent dielectric loss behavior in the frequency range from 1 MHz to 3 GHz, and the maximum of the dielectric loss factor approximated to 15,000.

The preparation of polyaniline waterborne latex nanoparticles and their films with anti-corrosivity and semi-conductivity

An emulsion polymerization of aniline was performed in micellar solution of sodium dodecylbenzene sulfonate (SDBS), dodecylbenzene sulfonic acid (DBSA), or sodium dodecylsulfate (SDS) as both emulsifier and dopant to obtain stable nano-polyaniline (PAN) waterborne latexes. The direct film formability and anti-corrosivity of PAN latexes were studied. The uniform PAN–SDS/polyvinyl alcohol (PVA) composite films were prepared by casting a direct mixture of the PAN latex and PVA aqueous solution. The emulsifier species and concentration, mixing way of emulsifier with aniline, and polymerization solution acidity, have a remarkable influence on the diameter and stability of PAN latex particles. The molar ratio of emulsifier over aniline was optimized for the synthesis of the PAN latex with small particle size and good properties including film formability, anti-corrosivity, and electrical conductivity. The smallest diameters of PAN–SDBS, PAN–DBSA, and PAN–SDS spherical particles determined by laser particle analyzer and electron microscopes are 2500, 40 and 5 nm, respectively. A good direct film formability of the PAN latex nanoparticles was found. The film formed by solution-casting method is thin, smooth and metal-lustrous. The electrochemical impedance spectroscopy was used to evaluate the impedance of the PAN latex films sandwiched between acrylic resin and iron sheet. It is found that the PAN has excellent anti-corrosivity, implying a possibility of direct application as metal anti-corrosive coating. A semi-conductive PAN/PVA nanocomposite film containing a very small amount of PAN nanoparticles exhibits low percolation threshold of PAN concentration of 0.1 wt.%.

Preparation and characterization of a polyaniline/poly(butyl acrylate–vinyl acetate) composite as a novel conducting polymer composite

AbstractThis is the first report on the preparation and characterization of a polyaniline/poly(butyl acrylate–vinyl acetate) composite. The composite was prepared by the emulsion polymerization of aniline in a medium containing poly(butyl acrylate–vinyl acetate). Films prepared from the composite (cast from an aqueous medium) had excellent mechanical properties and could be stretched up to 900%. The resultant composite was soluble in common organic solvents, and a stable water‐based dispersion could also be prepared. An electrical conductivity of 2.2 S cm−1 was obtained. Cyclic voltammograms revealed that the composite was electroactive. It had excellent adhesion to either glass or steel plate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2525–2531, 2003

Melt/solution processable conducting polyaniline: Elastomeric blends with EVA

AbstractPolyaniline (PANI) protonated with dopant, the sulfonic acid of 3‐pentadecylphenoxyacetic acid (SPDPAA; synthesized from an inexpensive naturally existing biomonomer, cardanol), was blended with an elastomeric polymer, the ethylene vinyl acetate (EVA) copolymer. Blending was performed either by emulsion polymerization of aniline into the EVA matrix or by the solution‐mixing method. Thin films were prepared by the conventional melt‐processing technique for an emulsion‐polymerized system and by the solution‐casting method for a solution‐mixed system. In the case of the emulsion‐polymerized system, the percolation threshold occurs at a very low weight percentage of PANI, and a maximum conductivity value of 0.85 S cm−1 was obtained for 28.5 wt % of PANI. These elastomeric conducting blends were characterized by elemental analysis, FTIR and UV‐visible spectral analysis, conductivity measurements, SEM, XRD, tensile properties, TGA, and DSC. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1438–1447, 2002; DOI 10.1002/app.10408

Effects of water phase concentration on the emulsion polymerization of polyaniline

The emulsion polymerization of aniline in three-phase system of xylene-functionalized protonic acid-water was carried out using (NH4)2S2O4 as oxidant. The influences of water phase concentration on the viscosity, conductivity, transmittance of polyaniline(PAN) latex and its powders were studied. The results show that the properties of PAN prepared through the emulsion polymerization are influenced by the amount of water used in the polymerization. The morphology of PAN varies with the water phase concentration used in the polymerization, which may result in the change of properties of PAN latex and its powders. When the volume fraction of water (φ) is about 20%–30%, the prepared PAN powder has higher conductivity, and the PAN latex has appropriate viscosity and particle size. The consumption of xylene was reduced at high φ value.

Change of conductivity of polyaniline/(styrene-butadiene-styrene) triblock copolymer composites during mechanical deformation

A measuring method for a conductivity change through a current change during extension deformation or compression deformation of conductive elastomeric composites composed of a polyaniline (PAn)/styrene-butadiene-styrene (SBS) triblock copolymer was established. The composites were prepared by in situ emulsion polymerization of aniline in the presence of SBS using dodecylbenzene sulfonic acid (DBSA) as an emulsifier and a dopant. The product was melt-processed (MP), solution-processed (SP), or secondary doped with m-cresol (SSP). The results for measurement of the conductivity change of the composites processed by the three different methods showed that for the MP and SP samples conductivity increases with extension, whereas for the SSP sample when the PAn content is lower than the percolation threshold, conductivity diminishes with increasing extension, but when the PAn content exceeds the percolation threshold value, conductivity followed an empirical equation with a maximum value. During compression, the conductivities of most of the MP, SP, and SSP samples exhibited a maximum value with change of the compression force, except the MP sample with a higher PAn content, the conductivity of which increased with the compression force. All the differences are related to their different morphological structures.

Emulsion polymerization of aniline

In this communication, we report that aniline can be conveniently polymerized directly into conducting material using an emulsion polymerization technique. The polymerization is carried out in non-polar or weakly polar solvents in the presence of a functionalized protonic acid that acts simultaneously as a surfactant (emulsifier) and as a protonating agent (dopant) for the resulting electrically conducting polyaniline. It was found that the present direct, one-step preparation of polyaniline-protonic acid complexes in organic solvents may lead to polyaniline with significantly higher molecular weight than that prepared in acidic aqueous solutions. In addition, the present polyaniline-functionalized acid complexes displayed higher solubilities in non-polar or weakly polar organic solvents than corresponding complexes obtained by mechanically mixing the emeraldine base form of polyaniline with the protonic acid. Films cast from concentrated solutions routinely exhibit conductivities in excess of 100 S cm −1. Additionally, it was found that, using the emulsion polymerization route, polyaniline-functionalized protonic acid complexes of fibrillar morphology can be produced, which have an exceptional degree of crystalline order and orientation.

Emulsion polymerization of aniline

High quality polyaniline, PANI, has been made by polymerization of aniline using a direct one-step emulsion polymerization technique. The polymerization is carried out in an emulsion comprising water and a non-polar or weakly polar organic solvent in the presence of the functionalized protonic acid dodecylbenzene sulphonic acid (DBSA). We found that using the emulsion polymerization technique, conducting PANI-DBSA complexes can be produced that exhibit high molecular weight, high conductivity and high solubility in organic solvents in the electrically conducting state. We found, furthermore, that using this technique, in-situ production of PANI-DBSA fibrils can be produced that exhibit a high aspect ratio and an exceptional degree of crystalline order and orientation.