Polyaniline Clay Research Articles

Optimizing the Synthesis and Thermal Properties of Conducting Polymer–Montmorillonite Clay Nanocomposites

Given the availability of a wide range of properties not possessed by individual materials, nanocomposites based on conducting polymers and inorganic materials have attracted much deserved attention. However, there has been little attempt to optimize the synthesis and thermal properties of polyaniline–clay nanocomposites. In this study, the synthesis and thermal properties of polyaniline (PANi) and polyaniline–clay nanocomposites (PACN) were performed by systematically varying the feed composition. Both PANi and polyaniline–montmorillonite (MMT) nanocomposites were prepared by using ammonium persulfate (APS) as the oxidant. The chemical structure of the nanocomposites was studied by Fourier transform infrared spectroscopy (FTIR). FTIR spectra confirmed the presence of clay in the nanocomposites and the existence of mainly the emiraldine form of PANi. Thermal analysis was performed by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology and structure of PANi and PACN were studied by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). Our results confirm the intercalation and partial exfoliation of clay. This study also showed that increasing the oxidant concentration resulted in decreasing thermal stability and melting temperature of PANi. The reinforcement of PANi with MMT resulted in increased thermal stability and increased melting point of PANi. It was also shown that the addition of only about 0.1 wt% of APS resulted in an optimal thermal stability and melting point for PANi.

A novel water-based epoxy coating using self-doped polyaniline–clay synthesized under supercritical CO2 condition for the protection of carbon steel against corrosion

The synthesis of a polyaniline–clay nanocomposite (PAniC NC) was achieved using the in situ polymerization of aniline in a Cloisite® 30B nanoclay suspension in a supercritical CO2 (Sc-CO2) medium. The interfacial co-polymerization of aniline (ANI) and m-aminobenzenesulfonic acid (SAN) in the presence of Cloisite® 30B was performed in Sc-CO2/water to produce the SPANI-clay NC. The NC was then mixed with a water-based hardener. This water-based composite is developed with the goal of reducing environmental and health risks. The use of this Sc-CO2 technique produced a composite material that resulted in the enhanced protection of carbon steel against corrosion when compared to a similar composite synthesized under atmospheric conditions. The materials obtained were characterized using UV/visible spectroscopy, X-ray powder diffraction and scanning and transmission electron microscopy. The anti-corrosion performance and the adhesion properties of these coatings were evaluated using standardized tests. Electrochemical impedance spectroscopy was also used to determine the electrochemical properties of these anti-corrosion coatings. Better exfoliation and dispersion of the clay was achieved using the Sc-CO2 medium resulting in superior performances in corrosion and electrochemical tests because of the higher level of intercalation.

Evaluating protection performance of zinc rich epoxy paints modified with polyaniline and polyaniline-clay nanocomposite

Abstract Cloisite 30B nano clay was delaminated in the presence of aniline monomers using supercritical CO 2 (ScCO 2 ) process. Rapid mixing polymerization of aniline monomers was done in supercritical CO 2 to produce exfoliated polyaniline clay (PAniC) nanocomposites with high barrier properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and XRD analysis have been used to characterize morphology and structure of the synthesized products. The synthesized products were added to a commercial zinc rich epoxy primer to improve its initial barrier properties. Barrier properties of unmodified and modified primers were then studied by determining water vapour transmission (WVT) rate of their free films, free corrosion potential ( E corr ) and electrochemical impedance spectroscopy (EIS) measurements of carbon steel coated panels. Results showed that samples modified with PAniC nanocomposites had better barrier properties compared to PAni modified and original primers. The coating resistance of PAniC modified primer was at least one order of magnitude higher than other primers at the begining of immersion. After one year of immersion, the coating resistance of original, PAni modified and PAniC modified primers were found to be 267, 1610 and 5540 ohm, respectively.

A facile and inexpensive method for the preparation of conducting polyaniline–clay composite nanofibers

Hybrid nanofibers constituted by polyaniline doped with phosphoric acid (PAniPh) and two different clays: pristine montmorillonite (MMT-Na+) and organoclay functionalized with amino undecanoic acid (MMT-COOH), were successfully prepared by employing a very simple procedure based on previous swelling the clay in anilinium salt solution followed by in situ polymerization under static conditions and low [acid]/[aniline] molar ratio. The nanocomposites were characterized by X-ray diffraction (XRD), field emission-scanning electron micrograph (FEG-SEM), transmission electron microscopy, Fourier transform-infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, electrical conductivity and thermal gravimetric analysis (TGA). Nanocomposites containing around 12% of clay resulted in conducting nano-fibers with ramose structure and higher electrical conductivity than pure PAniPh. The extended conformation was also confirmed from UV–vis spectrum. The best surface conductivity (2.3S/cm) and highest extended conformation were observed for the PAniPh/MMT-COOH nanocomposite.

Preparation of polyaniline and self-doped polyaniline–clay nanocomposites in supercritical CO2: Synthesis and conductivity study

Supercritical CO2 (ScCO2) was used as processing medium to prepare polyaniline (PANI) and self-doped polyaniline (SPANI)–clay nanocomposites. Interfacial copolymerization of aniline (ANI) and m-aminobenzene sulfonic acid (SAN) in the presence of Cloisite 30B nano-clay powder was performed in ScCO2/water to produce PANI and SPANI–clay nanocomposites. Different ratio of aniline to SAN was used and the temperature profile during copolymerization was measured to monitor the copolymerization process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR) and UV–vis spectroscopy were used to characterize the morphology and the structure of the resultant nanocomposites. SEM and TEM results reveal that nano-clays are fully dispersed in the ScCO2 synthesized nanocomposites, while in the atmospheric synthesize ones the nano-clays have tightly bonded agglomerated and are still stack to each others. FTIR and UV–vis results revealed that the products are in high conductive emeraldine salt state. The influences of clay loading on the conductivity of resulting nanocomposites were studied. It was found that the conductivity of nanocomposites is slightly lower than pristine polymers and decreases by nano-clay loading. Conductivity of compressed pellets of pristine PANI and SPANI were measured during the storage for different periods of times to evaluate aging properties. It was found that resulted SPANI has stable conductivity compare to the PANI nanocomposite.

Comparative assessing on corrosion protection effects of zinc rich ethyl silicate primers modified with undoped and HCl doped PAni–clay nanocomposite

This paper presents the works carried out to synthesise undoped and doped polyaniline–clay nanocomposite (PAniCN) by chemical oxidative polymerisation of aniline monomers in the presence of Cloisite 30B nanoclay powders. Fourier transform infrared analysis was used to characterise the synthesised nanocomposites. Electrical conductivity test was used to compare the conductivity of different PAniCN powders. The synthesised nanocomposites were added to a zinc rich ethyl silicate primer to modify the barrier properties of the primer. Unmodified and modified primers were applied on the carbon steel panels separately. The corrosion protection performances of different primers were evaluated via determining open circuit potential (OCP) and electrochemical impedance spectroscopy during immersing in 3·5% sodium chloride solution for a period of 120 days. Electrochemical impedance spectroscopy analysis showed that the coating resistances Rc of modified primers were higher than the original primer. Coating resistance of the undoped and doped PAniCN modified primers and original primer were reached to 6·056×103, 5·565×103 and 2·773×103 Ω cm2 after 120 days of immersing respectively. Open circuit potential measurements were carried out in order to evaluate the cathodic protection ability and duration. These measurements revealed that although the undoped PAniCN modified primer showed the highest resistance, the OCP of the panels coated with this modified primer pass through safety region [−0·86 V(SCE)] after 120 days of immersion. Besides salt spray test (according to ASTM B117-03) was used as a widespread accelerated test to evaluate the protection performances of primers. In salt spray test spots of rust appear on the surface of the panels coated with undoped PAniCN modified primer after 1500 h of exposure. The results of OCP measurement test were confirmed by the results of salt spray test.

Synthesis of exfoliated polyaniline–clay nanocomposite in supercritical CO 2

This paper presents the works done to synthesize fully exfoliated polyaniline–clay nanocomposites (PCNs) with high purity via in situ polymerization of aniline in Cloisite 30B nano-clay suspension in supercritical CO 2 (ScCO 2) medium. The Cloisite 30B was first delaminated with ScCO 2 treatment in the presence of aniline monomers. Ammonium peroxydisulfate (APS) solution was added rapidly into the mixture of delaminated Cloisite 30B and aniline monomers to produce PCNs. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and XRD analysis have been used to characterize the morphology and structure of the as-synthesized product. SEM results reveal that nano-clays are fully exfoliated in the final nanocomposite which is synthesized in ScCO 2. FTIR and UV–vis analysis showed that the resulted polyaniline (PANI) had been in highly conductive emeraldine salt state and ScCO 2 does not have any effect on chemical structures of the PANI.

Synthesis of Various Polyaniline / Clay Nanocomposites Derived from Aniline and Substituted Aniline Derivatives by Mechanochemical Intercalation Method

Polyaniline clay nanocomposite can be prepared by mechano‐chemical method in which intercalation of anilinium ion into the clay lattices accomplished by mechanical grinding of sodium montmorillonite (Na+MMT) in presence of anilinium hydrochloride at room temperature using mortar & pestle for about 30 min and subsequent grinding with oxidizing agent, ammonium peroxysulfate. The appearance of green colour indicates the formation of polyaniline/clay nanocomposite (PANI/Clay). Similarly aniline derivatives like o‐toludine and o‐anisidine in the form of HCl salt can form intercalation into the clay lattices. The intercalated aniline derivatives were ground mechanically in presence of oxidizing agent ammonium peroxysulfate lead to formation of substituted polyaniline/ clay nanocomposites. The characteristics of various polyaniline‐clay nanocomposites were investigated using UV‐Visible, FT‐IR, cyclic voltammetry studies.

Characterization and AC conductivity of polyaniline–montmorillonite nanocomposites synthesized by mechanical/chemical reaction

Polyaniline–clay nanocomposites were prepared by solid state polymerization of aniline chloride in the interlayer of montmorillonite through the use of persulfate of ammonium as oxidant. The proportion of aniline to clay and the molar ratio of oxidant to aniline are being varied. The analyse of UV visible and FTIR spectroscopy demonstrated that aniline has been polymerized to polyaniline (PANI) in its conducting emeraldine form. The conformation adopted by PANI chains in the clay interlayer depended on the molar ratio of aniline to montmorillonite. Thermogravimetric analysis of the nanocomposites suggested that polyaniline chains are more thermally stable than those of free polyaniline prepared by solid–solid reaction. The AC conductivity data of different synthesized nanocomposites were analyzed as a function of frequency. Low frequency conductivities of polyaniline/montmorillonite nanocomposites materials ranges from 0.18 to 5.6 × 10 −3 S/cm. All characterization data were compared to those of free polyaniline that was synthesized using a solid–solid reaction.

Intercalated conducting polyaniline–clay nanocomposites and their electrical characteristics

A nanocomposite material, which consists of polyaniline (PANI) and inorganic Na +-montmorillonite (MMT), was synthesized via a microemulsion polymerization method, in which the Na +-MMT was forced to be swollen, following insertion of a mixture of aniline monomer, sodium lauryl sulfate and pentanol under sonication into its gallery. The d-spacing of the PANI/Na +-MMT nanocomposite was found to become wider about 2.3 Å than that of the pure Na +-MMT particles, due to the successful intercalation of PANI into Na +-MMT layers. The electrorheological (ER) fluid based on the fabricated PANI/Na +-MMT nanocomposite was prepared by dispersing the particles in insulating silicone oil. Dynamic mechanical properties of the ER fluid were investigated via an oscillatory test using a vertical oscillation rheometer.

Studies on the formation of self-assembled nano/microstructured polyaniline–clay nanocomposite (PANICN) using 3-pentadecyl phenyl phosphoric acid (PDPPA) as a novel intercalating agent cum dopant

Novel self-assembled micro/nanostructured polyaniline–clay nanocomposite (PANICN) materials were prepared by in situ intercalative emulsion polymerization of aniline in aqueous dispersion of clay using functionalized amphiphilic dopant, 3-pentadecyl phenyl phosphoric acid (PDPPA) derived from renewable resource. The structural effect of PDPPA on the morphology, electrical conductivity and phase transition temperature of PANICNs was compared with nanocomposites prepared using dodecyl benzene sulphonic acid (DBSA) and HCl. X-ray diffraction and scanning electron microscopic (SEM) studies revealed the formation of monolayer of protonated PANI intercalated nanoclay layers with template polymerized self-assembled micro/nanostructured PANI on the surface of the clay. Nano/microstructured PANIs were formed by the supra-molecular self-assembling of the inter-chain hydrogen bonding, interplane phenyl stacking and electrostatic layer-by-layer self-assembling (ELBS) between polarised alkyl chains present in dopant anions and were manifested using Fourier transform infrared spectroscopy and differential scanning calorimetry.

Solvent free synthesis of polyaniline-clay nanocomposites from mechanochemically intercalated anilinium fluoride.

Nanocomposites consisting of conducting polyaniline and clay minerals were successfully synthesized from mechanochemically intercalated anilinium fluoride; the nanocomposites prepared by the mechanochemical intercalation method contained much more polyaniline in the clay layers than those prepared by a conventional solution method.

SYNTHESIS AND ELECTRORHEOLOGICAL CHARACTERIZATION OF POLYANILINE AND NA+-MONTMORILLONITE CLAY NANOCOMPOSITE

Polyaniline- Na +-montmorillonite nanocomposite particles were synthesized using an emulsion intercalation method, and electrorheological (ER) fluids were produced by dispersing the synthesized nanocomposite particles in an electrically-insulating silicone oil. The emulsion of an aniline monomer with dodecyl benzenesulfonic acid was inserted into the layers of clay, and polymerization was processed by adding the oxidant initiator solution. DBSA as a emulsifier and a dopant took a important role for polyaniline clay nanocomposite. This insertion of polyaniline was confirmed by X-ray diffraction. To observe its ER properties, we measured the shear viscosity and the shear stress by controlling shear rate. Furthermore, we conducted dynamic tests to investigate the viscoelastic properties of the ER fluid under an electric field in the linear viscoelastic region.

Physical characterization of emulsion intercalated polyaniline–clay nanocomposite

Abstract Using emulsion polymerization method, polyaniline (PAN)–Na+–montmorillonite (MMT) clay nanocomposites were synthesized. Dodecylbenzenesulfonic acid (DBSA) was used as an emulsifier and dopant during emulsion polymerization. The X-ray diffraction patterns showed that PAN–DBSA was intercalated between clay layers in the order of nanoscale. The room temperature (RT) dc conductivities of nanocomposites were 1–10 −3 S / cm depending on the molar ratio of dopants used. Temperature dependence of dc conductivity for the nanocomposites followed a quasi-one-dimensional (1D) variable range hopping (VRH) model. From temperature dependence of electron paramagnetic resonance experiments, magnetic properties and the density of states of the systems were obtained. The doping level of the nanocomposites was deduced from the results of X-ray photoelectron spectroscopy experiments. From the comparison of physical properties between PAN with clay and PAN without clay, the effects of dopant and the layer of clay on charge transport and structure are discussed.