Polyaniline/zeolite LTA composites and electrical conductivity response towards CO

Electrical conductivity response of polyaniline/zeolite composites towards CO is investigated in terms of dopant type, dopant concentration, zeolite LTA content and zeolite pore size. Both MA and HCl doped polyanilines respond with comparable magnitudes towards CO; the latter responses are slightly smaller for the same doping level. Addition of zeolite 4A reduces the electrical conductivity response but improves the sensitivity towards CO with increasing zeolite concentration up to 40% w/w. This concentration is evidently below the percolation threshold value, which is estimated to be above 50% w/w. Composite with zeolite 3A has a comparable sensitivity value relative to that of pure polyaniline. Composites of 4A and 5A have greater sensitivity values over that of the pure polyaniline at the CO concentration range between 16 and 1000 ppm. Zeolite 5A is the most effective mesoporous material in promoting interaction between CO and polyaniline because of its largest pore size of 5 Å, relative to the zeolite 3A and 4A which have the pore sizes of 4 and 3 Å, respectively.     

Electrical and structural analysis of conductive polyaniline/polyimide blends

Conducting films of dodecylbenzenesulfonic (DBSA)‐doped polyaniline/polyimide (PANI/PI) blends with various compositions were prepared by solvent casting followed by a thermal imidization process. Electrical and physical properties of the blends were characterized by infrared spectroscopy, an X‐ray diffraction technique, thermal analysis, a UV‐vis spectrophotometer, a dielectrometer, and conductivity measurements. The blends exhibited a relatively low percolation threshold of electrical conductivity at 5 wt % PANI content and showed higher conductivity than that of pure DBSA‐doped PANI when the PANI content exceeded 20 wt %. A lower percolation threshold and a lower compatibility was shown between the two components in the blends than those of PANI–camphorsulfonic acid/polyamic acid (PANI–CSA/PAA). A well‐defined layered structure due to the alignment of the long alkyl chain dopant perpendicular to the PANI main chain was evidenced by WAXD spectra. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2169–2178, 1999     

Fabrication and properties of solution‐cast polyaniline/carboxymethylchitin blend films

Blend films consisting of polyaniline in emeraldine base form (PANI EB) dispersed in partially cross‐linked carboxymethylchitin (CM‐chitin) were prepared by solution casting, and characterized for their physical, thermal, and electrical properties. Homogeneous and mechanically robust blend films were obtained having PANI EB contents up to 50 wt % in the CM‐chitin matrix. FTIR spectra confirm intimate mixing of the two blend components. The thermal stability of the blend films increased with increase of PANI EB content, suggesting the formation of an intermolecular interaction, such as hydrogen bonding, between PANI EB and CM‐chitin chains. The addition of PANI EB into the pure CM‐chitin film resulted in a decrease in electrical conductivity of the films owing to disruption of ionic conduction of the CM‐chitin structure. After doping the blend films by immersion in HCl solution, the electrical conductivity of the HCl‐doped films increased with increase of the PANI EB content to a maximum value of the order of 10^?3 S/cm at 50 wt % PANI EB content. The electrical conductivity of the blend films was also dependent on the HCl concentration as well as on the type of acid dopant. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and studies of exceptionally crystalline polyaniline thin films

Highly crystalline camphor sulfonic acid (CSA)‐doped polyaniline (PANI) thin films cast from m‐cresol and N‐methylpyrrolidone (NMP) were investigated. PANI powder prepared by chemical oxidative polymerization subjected to doping–de‐doping–re‐doping procedures was cast into thin films using NMP and m‐cresol as solvents. X‐ray diffraction (XRD) reveals the presence of exceptionally highly crystalline or rather ordered regions in the PANI film samples prepared from m‐cresol. Atomic force microscopy (AFM) images also support the presence of crystalline regions on the surface of these films. The DC electrical conductivity of m‐cresol‐cast PANI is found to be quite high, and much higher than that of NMP‐cast PANI. The free‐carrier absorption tail extending to the near‐infrared region observed in the optical absorption spectrum of the m‐cresol‐cast PANI films suggests a metallic nature and regular structural arrangement in these films. Both inter‐chain and intra‐chain ordering brought about as a result of CSA doping, secondary doping effect of m‐cresol and ultrasonication are suggested to be the prime factors contributing towards the observed excellent crystallinity of these PANI films as evident from the XRD and AFM studies. The marked thermal stability of the m‐cresol‐cast PANI films is also established based on the variation of DC electrical conductivity with temperature and on thermogravimetric analysis. Copyright © 2012 Society of Chemical Industry     

不同酸掺杂聚苯胺的电化学聚合及性能

采用循环伏安（CV）法在镀金PET膜上分别聚合了硫酸（H2SO4）、十二烷基苯磺酸（DBSA）、硫酸-十二烷基苯磺酸掺杂的聚苯胺（PANI）膜,对比研究了掺杂酸种类对PANI结构和性能的影响。结果表明,SO42?、DBSA?可以随聚合过程进入PANI分子链;H2SO4掺杂的PANI具有较高的电导率,但是在空气中的稳定性较差;大分子的DBSA使PANI优先产生单螺旋的纤维,提高了PANI在平行分子链方向上的结晶度和在空气中的稳定性;相对于单一酸掺杂,复合酸掺杂的PANI在酸溶液中电扫描表现出优良的循环伏安特性,在保持较高电导率的同时,提高了PANI在空气中的稳定性。     

Processable conductive blends of polyaniline/polyimide

By using camphorsulfonic acid (CSA) to protonate polyaniline (PANI), the counterion enabled the PANI–CSA complex processable as a solution phase. So camphorsulfonic acid (CSA)-doped polyaniline/polyimide (PANI/PI) blend films were prepared by the solvent casting method using N-methylpyrrolidinone (NMP) as a cosolvent followed by thermal imidization. The conductivity of the PANI–CSA/PAA (50 wt % PANI content) is greater than that of the pure PANI sample at room temperature. As the thermal imidization proceeded, molecular order of polymer chain structure was improved in the resulting PANI–CSA/PI film due to the annealing effect of PANI chain, and this PANI–CSA/PI film showed higher conductivity than PANI–CSA and PANI–CSA/PAA film. PANI–CSA/PI blend films had a good thermal stability of conductivity at high temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1863–1870, 1998     

Synthesis of nano‐sized ZnO and polyaniline‐zinc oxide composite: Characterization,stability in terms of DC electrical conductivity retention and application in ammonia vapor detection

Nano‐sized particles of Zinc oxide (ZnO) were synthesized using a new chemical rout. The chemical oxidative polymerization of aniline in the presence of nano ZnO was employed to synthesize a polyaniline‐zinc oxide (PANI‐ZnO) nanocomposite. The material was characterized by using transmission electron microscopy, XRD, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and Thermogravimetric analysis (TGA). The conductivity measurements showed the resulting composites possessed higher conductivity as compared to pure polyaniline (PANI). The nanocomposite exhibited fairly sensitive towards solution of aqueous ammonia (NH₃), when it was exposed to various concentrations of NH₃ in an ambient room temperature. The results show that the sensor has good sensitivity and good repeatability upon repeated exposure to NH₃. PANI‐ZnO nanocomposite was also used to study electrical conductivity under isothermal conditions in the temperature range 50–130°C. The composite was found stable under ambient conditions below 90°C in terms of DC electrical conductivity retention. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Melt‐processed polyaniline nanofibers/LDPE/EAA conducting composites

The melt‐processable polyaniline nanofibers doped with superfluous dodecylbenzenesulfonic acid (PANI‐DBSA) were synthesized using the interfacial polymerization and thermal doping technique. Conducting composites composed of PANI‐DBSA nanofibers, low‐density polyethylene (LDPE), and ethylene‐acrylic acid copolymer (EAA) as compatibilizer were prepared by melt processing. The effects of PANI‐DBSA nanofibers on the electrical conductivity, and mechanical properties, and morphological structure of the composites were investigated. As a result, the conducting composites had lower percolation threshold (4 wt%) due to the easy formation of conducting paths for fibrillar‐like PANI‐DBSA in the LDPE matrix, which was also confirmed by the frequency dependence of the real part of the AC conductivity. The Scanning electron microscopy (SEM) images indicated that the PANI‐DBSA nanofibers were dispersed uniformly in the matrix. The mechanical properties of the composites were improved at the low PANI‐DBSA load (about 1 wt%), but they were deteriorated at high PANI‐DBSA content. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Electrical conductivity and mechanical properties of polyaniline/natural rubber composite fibers

Electrically conducting elastomer fibers based on natural rubber (NR) and up to 10% w/w polyaniline (PANI) in its emeraldine base (EB) form were fabricated by a wet spinning process. The resulting fibers at various PANI contents were doped by immersion in aqueous HCl solution, which converted the PANI to the electrically conductive emeraldine salt (ES) form. The morphology of the composite fibers was studied by scanning electron microscopy (SEM). PANI particles were inhomogeneously distributed in the NR matrix. The electrical conductivity of the fibers increased with the increasing PANI‐ES content and leveled off at a value of around 10^?3 S/cm at PANI‐ES concentration of 5% w/w. The fibers retained most of their elasticity upon doping, while the tenacity was somewhat reduced. Gratifyingly, the electrical conductivity of the new elastomer fibers was preserved upon elongational deformation, even if strains as large as 600% were applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and characterization of tanninsulfonic acid doped polyaniline–metal oxide nanocomposites

Composites of conducting polymers and metal oxides have a potential role in electronic devices because of their enhanced physical and electronic properties. An in situ synthesis of metal oxide nanocomposites of polyaniline (PANI) and tanninsulfonic acid doped PANI was carried out at ?10°C with two different ratios of aniline to sodium persulfate (oxidant) and the simultaneous incorporation of TiO₂, Al₂O₃, and ZnO nanopowders. The products were characterized by X‐ray diffraction (XRD), thermal analysis, spectroscopy, and electrical conductivity measurements. XRD and thermogravimetric analysis confirmed the presence of the metal oxide in the final product, whereas the spectroscopic characterization revealed interactions among the tannin, metal oxides, and PANI. The electrical properties were determined by four‐point‐probe bulk conductivity measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Photoluminescence,FTIR, and electrical characterization of samarium(III) chloride‐doped polyaniline

The synthesized polyaniline (PANI) is doped with different concentrations of Samarium(III) chloride (SmCl₃). The electrical conductivity of doped PANI samples has been measured in the temperature range (300–400K). It has been found that dc conductivity increases with the increase of dopant concentration. Different parameters, based on the conductivity, such as pre‐exponential factor (σ₀) and activation energy (ΔE) have also been calculated. These parameters exhibit information about the nature and suitability of the dopant. Doped samples are characterized by FTIR and photoluminescence studies, which show the interaction of dopant with PANI. Two sharp peaks of different intensities from PL spectra at 388 and 604nm have appeared in doped PANI, which might be due to the effect of SmCl₃. It has been observed that SmCl₃ (dopant) shows noticeable changes in the electrical and spectroscopic properties of doped PANI. © 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     

Study of polyaniline polyacrylamide composites by positron annihilation technique

Polyaniline doped with nonoxidizing Bronsted acids is recognized as a conducting material, as its electrical conductivity changes with percentage of doping. In the present work, different percentages of doped polyaniline were blended with polyacrylamide and their electrical conductivities as well as the positron annihilation lifetimes were measured. Analysis of data yielded three lifetime components. It was observed that the value of the short lifetime component remained constant for doping concentration, whereas that of the intermediate component τ₂ decreased. The relative intensity pertaining to τ₂, however, increased with the increase in doped PANI concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 930–933, 2003     

Preparation and properties of polyaniline electrospun fiber web

The objective of this study is to fabricate the highly electrical conducting polymer fibers applicable to many conducting materials. Therefore, we tried to prepare polyaniline (PANI) thin fiber web by an electrospinning process by the following steps. First, PANI emeraldine base (EB) was prepared by oxidative polymerization. Second, the PANI EB was doped with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPSA), and subsequently that was dissolved in trifluoroacetic acid (TFA). Third, the PANI‐AMPSA solution was electrospun by an electrospinning process. Consequently, the PANI doped with AMPSA was successfully electrospun into thin fiber form, and the electrical conductivity was superior. Also, the electrical conductivity of the PANI‐AMPSA electrospun was increased by a simple redoping process with AMPSA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Room temperature preparation,electrical conductivity,and thermal behavior evaluation on silver nanoparticle embedded polyaniline tungstophosphate nanocomposite

An advanced nanocomposite, polyaniline tungstophosphate (PANI‐WP) cation exchanger, was synthesized by simple solution method and treated with silver nitrate resulting silver embedded PANI‐WP (PANI‐WP/Ag). Spectroscopic characterization of PANI‐WP/Ag was carried out by scanning electron microscopy, fourier transform infrared spectroscopy, UV‐Visible spectroscopy, and X‐ray diffraction. Electrical conductivity measurements and thermal effect on conductivity of PANI‐WP/Ag was studied after acid treatment. The dc electrical conductivity was found 3.06 × 10⁻³ S cm⁻¹ for HCl doped, measured by 4‐in line‐probe dc electrical conductivity measuring technique. Thermal conductivity is stable with all temperatures in isothermal studies showing excellent stability of PANI‐WP/Ag material. Hybrid showed better linear Arrhenius electric conducting response for semiconductors, stable upto 120°C. It was observed that conductivity is at the border of metallic and semiconductor region. POLYM. COMPOS., 37:2460–2466, 2016. © 2015 Society of Plastics Engineers     

Effect of Ni2+ as a codopant on the structure,morphology, and conductivity of nanostructured polyaniline

One‐dimensional nanostructures of polyaniline (PANI) doped with (1S)‐(+)‐10‐camphorsulfonic acid (D‐CSA) alone and with NiCl₂ as a codopant were synthesized via in situ polymerization. PANI nanofibers with diameters of about 200 nm were formed when PANI was doped with D‐CSA only. When NiCl₂ was added as a codopant, the morphology of PANI obviously changed. The effects and related mechanisms were investigated by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, inductively coupled plasma–atomic emission spectroscopy, and X‐ray diffraction, and the results indicated that Ni²⁺ destroyed the micelles' structure by chemical conjunction with ? SO₃H groups in camphorsulfonic acid (CSA) molecules, which were the key component in forming the CSA–aniline micelles. The combination between Ni²⁺ and SO in CSA with a lower addition of Ni²⁺ led to a reduction of CSA doping to PANI, but a higher loading of Ni²⁺ brought about the direct doping of Ni²⁺ to PANI, which caused a higher degree of doping and oxidation. The conductivity of PANI increased almost linearly with increasing Ni²⁺. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Doping effect of organic sulphonic acids on the solid‐state synthesized polyaniline

Polyaniline (PANI) salts doped with organic sulfonic acids (methanesulfonicacid, p‐toluenesulphonic acid, and dodecylbenzenesulphonic acid) were first synthesized by using solid‐state polymerization method. The polymers were characterized by Fourier transform infrared (FTIR) spectra, ultraviolet‐visible spectrometry, X‐ray diffraction, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and conductivity measurements. It was found that PANI doped with p‐toluenesulphonic acid is formed in conductive emeraldine oxidation state, and displayed higher doping level and cyrstallinity. On the contrary, PANI doped with dodecylbenzenesulphonic acid was lower at doping level and highly amorphous. In accordance with these results, the conductivity and electrochemical acitivity was also found to be higher in p‐toluenesulphonic acid‐doped PANI, and these properties were opposite in the case of dodecylbenzenesulphonic acid. The results also revealed that the morphology of dodecylbenzenesulphonic acid‐doped PANI was remarkably different from other PANI salts. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

樟脑磺酸掺杂聚苯胺的合成及性能研究

采用溶液聚合法,用樟脑磺酸(CSA)在间甲酚(m-c)与三氯甲烷(ch)的混合溶剂中对聚苯胺进行掺杂,掺杂能够使聚苯胺在保持较好溶解性的同时,提高其电导率。当PANI/CSA(mol/mol)=1/50时,制备出了电导率高达400 S.cm-1的PANI-CSA自支撑膜。采用四探针法测量了掺杂态聚苯胺的电导率,并用红外光谱(FT-IR)和热失重(TG)等方法表征了樟脑磺酸和盐酸掺杂的聚苯胺的结构和形态。     

On the prospects of polyaniline and polyaniline/MWNT composites for possible pressure sensing applications

This work highlights the prospects of applications of doped polyaniline (PANI) and Polyaniline–MultiWalled Carbon Nanotube (MWNT) composites with different dopants in pressure sensing devices. PANI and its nanocomposite samples in the form of pressed pellets show orders of change in electrical conductivity with applied pressure in the range 0–30 MPa, even for very small applied bias of a few milli‐volts. The percentage variation of electrical conductivity with applied pressure is strikingly large for PANI and its composite samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of LiCl as an additive in the polymerization reaction of aniline and its influence on the structural and electrical property of polyaniline

Doped polyaniline (PANI) is synthesized in aqueous HCl medium by ammonium persulphate (APS) as oxidant. We used LiCl during in situ polymerization of aniline to explore any improvement of electrical properties of PANI due to Li⁺ and HCl incorporation. We varied the HCl and LiCl molarity in the polymerization medium keeping the total Cl⁻ concentration constant. The level of Li⁺ loading was measured by fluorescence spectroscopy of doped PANI. The PANI was characterized by FTIR and UV–visible spectroscopy, XRD analysis, intrinsic viscosity measurement and optical microscopy. The conductivity of doped PANI was measured by four probe method. Hall effect measurement was also done to measure the resistivity and the charge carrier density of the doped polyaniline.