Polyaniline Clay Nanocomposites 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.

Polyaniline/clay nanocomposites. A comparative approach on the doping acid and the clay spacing technique

Polyaniline/clay nanocomposites (PCNs) have been synthesized by oxidative polymerization of aniline by using two different clay treatment techniques (mechanical agitation and ultrasonication), as well as two different doping acids (hydrochloric acid – HCl – and dodecylbenzene sulfonic acid – DBSA –). The effect of both conditions on their chemical nature, structure and morphology has been studied by Raman spectroscopy, X-ray Diffraction (DRX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). PCNs electrical conductivity was measured by the 4-probe technique. The results reveal that the type of clay treatment shows no impact on the PCNs morphology, but it does determine their final structure – either intercalation or exfoliation – which has a remarkable effect on the electrical conductivity. Moreover, the doping acid presented a strong influence on both morphology and electrical conductivity of the prepared PCNs. In this work, HCl doping and ultrasonication are highlighted as the optimal PCN synthesis conditions, since the highest electrical conductivity is reached with less time and energy consumption.

Nanofiber Polyaniline and Polyaniline-Clay Nanocomposite Prepared via Sonochemical and Sol-Gel Techniques

Polyaniline (PANI) and polyaniline-clay (PANI-clay) composite nanostructured materials were prepared via both ultrasonic irradiation and sol-gel preparation techniques. The molecular structure of prepared PANI and PANI-clay composite samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The characterization results confirm the nanostructure of prepared samples. BET surface area results were obtained for the prepared matrices. TEM and SEM images showed the morphology of the fabricated nanomaterials.

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.

Percolated conductive polyaniline-clay nanocomposite in polyvinyl chloride through the combined approach porous template and self-assembly

In this paper, we are reporting a novel strategy for the preparation of conductive polyaniline-clay nanocomposite in Polyvinylchloride (PVC) matrix by admicellar emulsion polymerization using a low cost renewable resource based sur- factant cum dopant. The highly oriented percolated network of polyaniline-clay nanocomposite in PVC matrix was revealed from the studies made by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FTIR) results suggested that porous template was formed by the noncovalent interactions among the hydroxyl groups present in the nanoclay edges and the chloride ions present in PVC matrix. Here, the bio-based surfactant, 4-hydroxy-2-pentadecyl benzene-1-sulphonic acid (PDPSA) performed multiple roles of dopant, emulsifier and soft template during the polymerization of anilinium + PDPSA - (An + PDPSA - ) in PVC-clay matrix. The prepared composite exhibited electrical conductivity (!dc) of 4.8·10 -2 S/cm and electromagnetic interference shielding efficiency (EMI SE) of 55.2 dB suggesting it as a prospectable candidate for the encapsulation of electronic devices in high technological applications.

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 and evaluating corrosion protection effects of emeraldine base PAni/clay nanocomposite as a barrier pigment in zinc-rich ethyl silicate primer

In the present work, polyaniline/clay nanocomposite (PAniCN) was synthesized by chemical oxidative polymerization of aniline monomers in the presence of Closite30B powders. XRD and SEM examinations were used to examine the intercalation and morphologies of PAniCN, respectively. Electrical conductivity test showed that the conductivity of final PAniCN was higher than pristine PAni by one order of magnitude. Synthesized nanocomposite was added to the zinc rich ethyl silicate primer to modify its barrier properties. The corrosion protection performances of modified and unmodified primers were evaluated using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution for a period of 120 days. It was found that the modified primer had higher barrier properties than original primer. After 120 days of immersion, resistance of modified and unmodified primers reaches 5.565×103Ωcm2 and 6.056×102Ωcm2 respectively. The OCP of both primers were lower than −800mV/SCE during the immersion. Besides, the OCP of modified primer was higher than the original primer due to the passivation and barrier effects of PAniCN. Results revealed that the performance of modified primer improved strongly.

Preparation and Anticorrosion Property of Polyaniliane/Organo-Clay Nanocomposite Coatings: Comparative Studies of Different Intercalating Agent

In this study, we present the first systematically comparative studies for the effect of intercalating agent on the property of polyaniline (PANI) -clay nanocomposite (PCN) materials. First of all, (4-carboxybutyl) triphenyl-phosphonium bromide (PC-4) and dodecyltriphenyl-phosphonium bromide (PC-12) were used as intercalation agent, separately, for the preparation of organophilic clay through cationic exchange reactions with Na+-montmorillonite (Na+-MMT) clay. Subsequently, organophilic clay was blending with aniline monomers followed by performing in-situ conventionally oxidative polymerization to give series of PCN materials. Subsequently, the as-prepared materials were characterized by Fourier-Transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (WXRD), and transmission electron microscopy (TEM). It should be noted that Na+-MMT modified with PC12 was found to reveal better dispersion than that of PC4-modified clay existed in polymer matrix based on studies of WAXRD and TEM. It should be noted that the PCN coatings containing PC12-modified clay platelets was found to reveal better corrosion protection than that of containing PC4-modified clay based on series of electrochemical corrosion measurements in saline. Effect composition on the electrical conductivity, optical and molecular weight of PANI of as-prepared PCN materials was also investigated by four-point probe technique, UV-visible absorption spectroscopy and gel permeation chromatography (GPC), respectively.

Development of electromagnetic shielding materials from the conductive blends of polystyrene polyaniline-clay nanocomposite

Electromagnetic interference shielding composite materials were developed from the conductive blends of nanostructured polyaniline-clay composite (PANICN) and Polystyrene (PS) by a one step host matrix assisted emulsion polymerization of anilinium salt of 3-pentadecyl phenol-4-sulphonic acid (3-PDPSA) in clay. 3-PDPSA was derived from cashew nut shell liquid, a low cost renewable resource based product. These blends were characterized using Uv–visible and FT-IR spectroscopy, XRD, electrical conductivity, thermal property, dielectric property and electromagnetic shielding efficiency. The interactions between the primary particles and host matrix were elucidated from the studies made through spectroscopy and rheology. The key finding of the research is that this low cost PANICNPS blend with superior electrical conductivity (7.6 × 10 −1 S/m), excellent thermal stability and EMI SE of 10–20 dB at 8 GHz makes them as a promising candidate for application in EMI shielding and antistatic discharge matrix for the encapsulation of micro electronic devices.

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 likeo-toludine ando-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.

Role of amphiphilic dopants on the shape and properties of electrically conducting polyaniline‐clay nanocomposite

AbstractThe role of functionality and rigidity of the amphiphilic dopants on the morphology and electrical property of the polyaniline‐clay nanocomposites (PANICNs) were studied by preparing polyaniline (PANI) and PANICNs using five structurally different amphiphilic dopants having backbone—phenyl, naphthyl, alicyclic, and alkyl groups. Effect of the size and functionality of the dopant on the extent of intercalation/exfoliation, morphology, thermal stability, and phase transitions were studied. PANICNs exhibited different morphologies such as nano/micro granules, rods, nanotubes, aggregated layers/clusters, and rice grain for PANICN‐2,6‐naphthalene sulphonic acid, PANICN‐para‐toluene sulphonic acid, PANICN‐stearic acid, PANICN‐dodecyl benzene sulphonic acid, and PANICN‐camphor sulphonic acid, respectively. X‐ray diffraction, Fourier transform infrared, and scanning electron microscopic studies showed that the self‐assembled nano/microstured aggregates were formed by the combined effect of many noncovalent interactions such as phenyl–phenyl stacking, hydrogen bonding, ion–dipole interaction, π–π stacking, and electrostatic layer‐by‐layer self‐assembling. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009.

Development of electromagnetic shielding materials from the conductive blends of polyaniline and polyaniline-clay nanocomposite-EVA: Preparation and properties

Electromagnetic interference shielding composite materials were developed from the conductive blends of nanostructured polyaniline (PANI) and polyaniline-clay nanocomposite (PANICN) with ethylene vinyl acetate (EVA) as host matrix. Electrically conducting nanostructured PANI and PANICNs were prepared using amphiphilic dopants, 3-pentadecyl phenol 4-sulphonic acid (3-PDPSA) derived from cashew nut shell liquid, a low cost renewable resource based product and dodecyl benzene sulfonic acid (DBSA). Effects of type and quantity of conductive fillers on the electrical conductivity, mechanical properties, thermal stability, morphology and electromagnetic shielding efficiency were investigated. The presence of exfoliated nanoclay and interaction between the conductive filler–host matrix in conductive films containing PANICNs manifested from the measurement on rheological property. Films with conductive filler (∼15% loading) showed a shielding effectiveness of ∼40–80 dB at 8 GHz which makes these conducting composites potential candidate for the encapsulation as EMI shielding materials for electronic devices.

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.

Structure – Directing Effect of Renewable Resource Based Amphiphilic Dopants on the Formation of Conducting Polyaniline-Clay Nanocomposite

Summary: The structure-directing effect of two amphiphilic dopants on the nucleation and growth mechanism during the formation of micro/ nanostructured polyaniline (PANI) and polyaniline-clay nanocomposites (PANICNs) is described. PANIs and PANICNs were prepared by in-situ intercalative emulsion polymerization of aniline using the amphiphilic dopants, 3-pentadecyl phenyl phosphoric acid (3-PDPPA) and 3-pentadecyl phenol–4-sulphonic acid (3-PDPSA), derived from cashew nut shell liquid, a renewable resource. These molecules act as intercalating agents, dopants and also as structure-directing agents. X- ray diffraction (XRD) and scanning electron microscopic (SEM) studies revealed the formation of lamellar/fibrillar – network in PANI- PDPPA and cylinder/rod morphology in PANI-PDPSA. Experimental data reveal that fibrillar morphology arises from the heterogeneous nucleation followed by an indefinite growth mechanism. On the other hand rod-like structures are formed from the self-assembled rod-like micelle guided polymerization through homonucleation followed by an anisotropic growth mechanism. Electrical conductivity measurement revealed lower conductivities for PANICNs than that of PANIs.

Structure – Directing Effect of Renewable Resource Based Amphiphilic Dopants on the Formation of Conducting Polyaniline‐Clay Nanocomposite

AbstractSummary: The structure‐directing effect of two amphiphilic dopants on the nucleation and growth mechanism during the formation of micro/ nanostructured polyaniline (PANI) and polyaniline‐clay nanocomposites (PANICNs) is described. PANIs and PANICNs were prepared by in‐situ intercalative emulsion polymerization of aniline using the amphiphilic dopants, 3‐pentadecyl phenyl phosphoric acid (3‐PDPPA) and 3‐pentadecyl phenol–4‐sulphonic acid (3‐PDPSA), derived from cashew nut shell liquid, a renewable resource. These molecules act as intercalating agents, dopants and also as structure‐directing agents. X‐ ray diffraction (XRD) and scanning electron microscopic (SEM) studies revealed the formation of lamellar/fibrillar – network in PANI‐ PDPPA and cylinder/rod morphology in PANI‐PDPSA. Experimental data reveal that fibrillar morphology arises from the heterogeneous nucleation followed by an indefinite growth mechanism. On the other hand rod‐like structures are formed from the self‐assembled rod‐like micelle guided polymerization through homonucleation followed by an anisotropic growth mechanism. Electrical conductivity measurement revealed lower conductivities for PANICNs than that of PANIs.

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.