Study on soluble polyaniline by positron annihilation technique

The solubility, electrical conductivity, and other properties of polyaniline (PANI) are highly dependent on its oxidation state. In this work, polyaniline (PANI1) prepared by peroxodisulphate induced polymerization of aniline in acidic aqueous medium in presence of benzenediazonium chloride salt was found to exist in lower oxidation state than emeraldine form of PANI and was highly soluble in common organic solvents. This polymer was subjected to positron annihilation spectroscopic study to investigate the correlation between the oxidation state of the polymer and defect sites generated by different degrees of protonation that in turn affect its electrical conductivity. The positron annihilation lifetime data were resolved to yield a three‐component fit for PANI1 subjected to different levels of protonation. The variation of positron annihilation parameters (τ_1,I₂) and Doppler broadening parameters (R, S) as a function of protonation level of the polymer indicate the dopant sites increase initially on protonation and reach a saturation value after a certain level of acidification. The lower value of electrical conductivity and the intensity of intermediate lifetime component (I₂) for PANI1 compared to PANI in emeraldine oxidation state indicate the presence of lesser number of quinoid–imine moieties that could undergo protonation and thus yield highly enriched trapping centers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

聚苯胺及其复合材料研究现状

对聚苯胺的结构、合成及其机理、质子酸掺杂 ,聚苯胺的应用 ,以及聚苯胺复合材料的研究现状进行了综合阐述 ,并详细介绍了有关煤基聚苯胺的研究情况。煤基聚苯胺和纯聚苯胺相比 ,电导率下降不大 ,而且成本降低、热稳定性增强 ;同时 ,煤基聚苯胺也为煤的非能源利用提供了新途径和新机遇 ,具有一定的推广价值。     

复合氧化剂在合成导电聚苯胺中的应用

以苯胺为单体,采用(NH4)2S2O8和抗坏血酸组成的复合氧化剂,在硫酸水溶液中,用化学氧化法直接合成导电聚苯胺。系统地研究了复合氧化剂配比、硫酸的浓度、氧化剂浓度等因素对苯胺聚合反应的影响。结果表明,该方法聚合反应的最佳条件为:在10~25℃的温度范围内,不加氮气保护条件下,苯胺1.0 mol/L,H2SO41 mol/L,(NH4)2S2O81 mol/L,(NH4)2S2O8/抗坏血酸(C6H8O6)的配比为10∶1,合成了电导率达1.33 S/cm、产率达82.17%的聚苯胺。通过红外光谱和X衍射研究了通过不同氧化剂聚合得到聚苯胺的结构变化,结果表明,复合氧化剂氧化聚合得到的聚苯胺结晶比通过过硫酸胺作氧化剂聚合得到的聚苯胺结晶好,并且相应基团在红外光谱上发生红移。     

Selective recognition of chloroacetic acids by imprinted polyaniline film

A novel conductive imprinted polyaniline (PAN) film is prepared by adding template during the PAN film preparation. Monochloroacetic acid (MCA) and trichloroacetic acid (TCA) were used as templates. The conductivity of imprinted PAN films was measured by the four‐point probe method. The conductivity changes of imprinted PAN films were compared to reference PAN reflecting the MCA and TCA specific sites on the surface of PAN films. The conductivities were linearly dependent on the template concentrations, and linear calibration curves were obtained in the range 1–30 and 1–40 ppm of the MCA and TCA, respectively. Excellent method reproducibility (standard deviation 0.04 S/cm⁻¹) was observed for the determination of 15 ppm MCA. The effect of various factors on preparation, properties, and recognition effects of the imprinted PAN films was investigated. The best electrical and mechanical properties were obtained with 7 × 10⁻⁴ mmol MCA as a template and doping agent. The measurements are carried out under room temperature, and the maximum conductivities are reached after about 10 and 20 min for reference and imprinted PAN film, respectively. Selectivity experiments were carried out with standard MCA, TCA, and five analogs (dichloro‐, dibromo‐, and monobromoacetic acid) in water. The results exhibited a good selectivity for the templates compared to structurally related compounds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrochromic properties of chemically prepared polyaniline

The electrochromic properties in non-aqueous medium of chemically prepared polyaniline films proved not to depend on the oxidizing agent used for the synthesis and were very similar to the properties of electrochemically prepared films. These properties were studied by measuring the optical contrast changes at fixed wavelengths in the uv/visible region during cyclic voltammetric scans and by applying 7 × 10³–8 × 10³ redox potential steps.     

Preparation and electroanalytical characterization of polyaniline: Polyacrylonitrile composite films

Electrically conducting composite films of polyaniline:polyacyrlonitrile (PANI:PAN) prepared with varying composition ratios of aniline mixed with a fixed amount PAN. The films of optimum thicknesses (0.10 mm) were obtained using an electrically operated automatic pressure machine. The films polymerized by oxidative polymerization using 0.1M potassium persulphate (K₂S₂O₈), undoped in 1M aqueous ammonia (NH₄OH) and doped in 1M hydrochloric acid (HCl). The conductivity of composite films was studied by keeping it in 1M HCl for different time period using 4-in-line probe DC electrical conductivity measuring instrument and the temperature dependence of DC electrical conductivity was studied using isothermal technique. The PANI:PAN composite film is used as a working electrode in an electrochemical cell. Chemically doped composite film is used as cathode (working electrode), aluminum metal foil as anode (counter electrode) and platinum foil as reference electrode. The electrolyte is of 0.05M aluminum chloride (AlCl₃) in dimethyl sulfoxide (DMSO). The voltage of the working electrode is stabilized with respect to the reference electrode and current applied between the working and counter electrode through a 9-V battery. The change in voltage versus time is plotted as the discharge curve and reversing the cell processes results in the doping of the composite films. The diffusion coefficient of the dopant ion (Cl⁻) present in the fully doped films were estimated by the galvanostatic pulse technique and found to bedifferent in different samples in the range of 10⁻¹⁶ to 10⁻¹² cm² s⁻¹. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel conducting polyaniline blends with cyanoresin

Novel conducting polyaniline (PANI)/cyanoresin (Cyan) blends were prepared by the addition of Cyan/dimethylformamide solutions to aniline monomer/dopant solutions and the in situ chemical oxidative polymerization of aniline with ammonium persulfate as an oxidant in aqueous p‐toluene sulfonic acid solutions. The PANI/Cyan blends were prepared with various compositions (5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, and 70:30), and blend films of PANI/Cyan were obtained with a casting method. The conductivity of the PANI/Cyan blend films was 10^?7 to 10^?2 S/cm, which was measured by a four‐probe technique. The tensile strength of the blend films was maintained with an increasing amount of PANI (up to 50 wt %), and this was attributed to intermolecular interactions such as hydrogen bonding between PANI and Cyan and a reinforcing effect through blending. This hypothesis was corroborated by Fourier transform infrared spectroscopy. Field emission scanning electron microscopy and thermogravimetric analysis were also used to investigate the morphology and thermal properties of the conducting PANI/Cyan blend films, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1035–1042, 2005     

聚苯胺季铵盐的合成及其性能研究

以邻氨基苯甲酸为原料,与氯乙醇反应生成2-氨基苯甲酸氯乙酯,然后用三乙胺季铵化合成了苯胺季铵盐,并将其聚合,通过红外光谱、紫外-可见光谱、X-射线衍射、循环伏安法和热重分析等对其结构与性能进行了研究。     

Preparation and characterization of polyaniline powder synthesized on microstructured aluminium

Aluminium surfaces were microstructured in 0.1 M HNO₃ by potentiodynamic anodic activation to potentials generating pitting. This surface was then used as an electrode to prepare polyaniline powder. The number of pits is responsible for the amount of powder produced. Emeraldine salt powder was successfully prepared from 0.4 M aniline in 0.5 M H₂SO₄ solution. Other acid solutions for deposition are not convenient because powders are electrochemically inactive (e.g., in 1 M HNO₃) or the electrode is covered by a film (e.g., in 0.5 M H₂C₂O₄).     

The characterization of polyaniline and polypyrrole composites by pyrolysis mass spectrometry

In this work, direct insertion probe pyrolysis mass spectrometry technique was applied to investigate the thermal and structural characteristics of electrochemically prepared polyaniline (PANI), polypyrrole (PPy), and their composites/copolymers synthesized either by electrochemical polymerization of pyrrole on PANI‐coated electrode (PANI/PPy) or by coating PANI on PPy (PPy/PANI) in H₂SO₄ solutions. It has been determined that the polymer first coated on the electrode degraded to a certain extent during the polymerization of the second. The extent of degradation was greater for PPy and increased with the increase in acid concentration. On the other hand, the detection of mixed dimers confirmed copolymer formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Conductive composites from polyaniline and polyurethane sulphonate anionomer

The present work describes the synthesis of conductive composite of polyurethane sulphonate anionomer (PUSA) and para toluene sulphonic acid doped polyaniline (PANI–PTSA). HCl‐doped PANI was synthesized by chemical oxidative polymerization of aniline in HCl, which was converted to PANI–EB by treatment with NH₄OH. PTSA doped PANI was synthesized from EB‐PANI by redoping with PTSA solution. PUSA was synthesized from 4, 4′‐diphenylmethanediisocyanate (MDI), polypropylene glycol (PPG), 1,4‐butanediol (BD), and ionic diol SDOL. The composite was prepared by mixing of the solutions of two polymer components in DMF and then solution casting. The products were characterized and analyzed by UV‐Vis and FTIR spectroscopy, thermogravimetry, differential scanning calorimetry and scanning electron microscopy. The conductivity was found to increase by 100 times with concomitant decrease in percolation threshold when polyurethane was replaced by PUSA in the composite for the same amount of polyaniline. The composite film was thermally stable upto ～300°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41600.     

Control of polyaniline conductivity and contact angles by partial protonation

Many studies require a specific value of conductivity when investigating conducting polymers. The conductivity of polyaniline can efficiently be controlled by partial protonation of the polyaniline base. Although this is a simple task in principle, practical guidelines are missing. In the present study, the changes in the conductivity of polyaniline base after immersion in aqueous solutions of various acids are reported. Polyaniline base has been reprotonated in aqueous solutions of picric, camphorsulfonic and phosphoric acids. The conductivity of partially reprotonated polyaniline varied between 10⁻⁹ and 10⁰ S cm⁻¹. The relation between the pH of a phosphoric acid solution, which was in equilibrium with polyaniline, and the conductivity σ is pH = 0.77 − 0.64 log(σ [S cm⁻¹]). The wettability, i.e. water contact angles, can similarly be set by partial protonation to between 78° for polyaniline base and 44° for polyaniline reprotonated in 1 mol L⁻¹ phosphoric acid. In solutions of picric acid, the transition from the non‐conducting to the conducting state occurs over a narrow range of acid concentrations, and the tuning of conductivity is consequently difficult. Phosphoric acid is well suited for the control of conductivity of polyaniline because of the moderate dependence of the conductivity on the acid concentration or pH. Copyright © 2007 Society of Chemical Industry     

Electrochemical behaviour of polyaniline in aromatic sulphonic acids

This report describes the synthesis and redox behaviour of polyaniline in aqueous solutions of benzene sulphonic acid and 4-toluene sulphonic acid. The characterization of the polymer was carried out by electronic spectra, FTIR studies and ¹HNMR in DMSO-d₆.     

Preparation and characterization of composites of polyaniline nanorods and multiwalled carbon nanotubes coated with polyaniline

Composites of polyaniline (PANI) nanorods and multiwalled carbon nanotubes (MWNTs) coated with PANI were prepared by in situ polymerization with perchloric acid as a dopant. Transmission electron microscopy images showed that the coexisting composites of PANI nanorods and MWNTs coated with PANI were formed at low MWNT contents. The interaction between MWNTs and PANI was proved by Fourier transform infrared and ultraviolet–visible spectra. The electrical conductivity of a dedoped PANI/MWNT composite with a 16.3 wt % concentration of MWNTs reached 3.0 × 10^?3 S/cm, which was 6 orders of magnitude higher than that of dedoped PANInanorods. The results also showed that coexisting composites of PANI nanorods and MWNTs coated with PANI had high electrochemical activity and good cyclic stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation of conducting polysiloxane/polyaniline composites

Polysiloxane/polyaniline microcomposites were prepared, in which polyaniline particles act as filler, thus combining the mechanical properties of polysiloxane matrix with conductivity of polyaniline. Two syntheses were evaluated: (1) homogeneous dispersion of a polyaniline colloid in the reaction mixture from which the polysiloxane matrix subsequently formed, and (2) the blending of previously prepared dry polyaniline particles with a liquid oligomeric siloxane resin followed by cure (“heterogeneous method”). Both methods lead to composites with evenly distributed filler. Electrical conductivity was achieved above 40 wt % of polyaniline, which is better obtained by the “heterogeneous” method. During the composite cure, the polyaniline particles, which are softer than the matrix, act as a catalyst and cause more efficient matrix crosslinking, thus leading to somewhat raised moduli. Although particulate fillers usually deteriorate the impact toughness, in the case of the prepared composites, the impact toughness was preserved due to the softer consistence of the filler, which hinders crack propagation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42429.     

导电聚苯胺的研究进展

概述了聚苯胺的几种合成方法及其溶解性问胚,并介绍了聚苯胺复合材料及聚苯胺的应用。     

Comparative study of conducting polyaniline/copper and polyaniline/nickel composites in the presence of surfactants

Polyaniline/copper and polyaniline/nickel composites were synthesized in the presence and absence of surfactants using ammonium persulfate as an initiator. The structural and surface characteristics of the composites were studied and compared using different techniques. The interfacial interactions and thermal stability of the composites were characterized using X‐ray diffraction and thermogravimetric analysis. Surface properties were investigated using scanning electron microscopy and energy‐dispersed X‐ray spectroscopy. The results indicate significant changes in the morphological and physicochemical properties of the composites when incorporating surfactants. The surfactant‐induced surface characteristics also have an effect on conductivity. Copyright © 2010 Society of Chemical Industry     

XPS study of aged polyaniline films

In this article, a study of the aging of conducting Polyaniline–Polystyrene blends using X‐ray photoelectron spectroscopy (XPS) and UV‐visible‐near IR analysis is presented. The physicochemical results are compared to those obtained by electrical measurements. XPS results confirm the existence of an oxidation process also deduced by the electrical conductivity studies. The N1s and S2p core level spectra decomposition allows to show that a deprotonation process and cyclization of tertiary amine occur during aging. The absorption spectrum shows a decrease of delocalized charges and the apparition of localized polarons after a long aging time. All these mechanisms are responsible of the electrical conductivity decrease observed during aging at elevated temperature. The results are presented for films of PANI–CSA–PSt blends, but the conclusions can be extended to pure conducting PANI–CSA films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3730–3736, 2003     

导电聚苯胺高分子复合材料的研究进展

重点介绍了聚苯胺结构与性能，综述了聚苯胺高分子复合材料的应用及其制备方法．水溶性聚苯胺的研究进展，并展望了聚苯胺复合材料具有广阔的应用前景。该工作对于全面了解聚苯胺具有一定的意义。     

Investigation on microstructural behavior of styroflex/polyaniline blends by WAXS

Styroflex/polyaniline (STF/PAni) blends were prepared by two routes namely by in situ and thermo mechanical processing method with various PAni compositions, namely, 0, 15, 30, and 45 wt %. The influence of volume fraction of PAni in the blends and synthetic routes of the STF/PAni blends on the volume resistivity and microcrystalline parameters have been investigated. The microcrystalline parameters such as the nanocrystal size (<N>), lattice disorder (g), interplanar distance (d_hkl), width of the crystallite size distribution, surface weighted crystal size (D_s), and crystallite area were evaluated from the wide angle X‐ray scattering profiles. The different asymmetric column length distribution functions namely, exponential, reinhold, and lognormal distribution methods were employed to probe the microcrystalline behavior of the STF/PAni blends and the results are compared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011