Effect of dopant and oxidant on the electrochemical properties of polyaniline/graphite nanoplate composites

Optimizing the synthesis parameters of polyaniline/graphite nanoplate (PANI/GNP) composite is essential to the final electrochemical performance. Herein, the electrochemical properties of PANI/GNP composites, prepared by in situ chemical polymerization using varying amounts of different oxidants, with or without the addition of 4‐dodecylbenzenesulfonic acid (DBSA) as dopant, were investigated. Cyclic voltammetric results suggested that a stoichiometric amount of the oxidant iron chloride (FeCl₃) was beneficial to the electrochemical properties of the composites. The use of ammonium persulfate (APS) instead of FeCl₃ as oxidant largely increased the actual PANI content, conductivity and specific capacitance of the PANI/GNP composites. The dopant DBSA increased the conductivity of the PANI/GNP composites but did not show a positive effect on the electrochemical behavior. The cyclic voltammograms of the PANI/GNP composites indicated that the pseudocapacitance of PANI contributes more than the electrical double‐layer capacitance of GNP to the capacitance of the composites, while the presence of GNP plays an essential role in the rate capability of the composites. In this study, PANI/GNP (1:1) composite synthesized with an APS to aniline molar ratio of 1 showed a balanced combination of high specific capacitance (180.5 F g^?1 at 20 mV s^?1) and good rate capability (78% retention at 100 mV s^?1). © 2018 Society of Chemical Industry     

Synthesis and characterization of polyaniline co-doped with nitric acid and dodecyl benzene sulfonic acid

Polyaniline (PANI) co-doped with nitric acid (HNO₃) and dodecyl benzene sulfonic acid (DBSA) was directly prepared by the chemical oxidative polymerization of aniline in an aqueous solution. When the molar ratio of HNO₃/DBSA was 0.3:7, the resulted co-doped PANI (PANI_H0.3D7) reached a maximum electrical conductivity of 7.98 S/cm. When the molar ratio of HNO₃/DBSA was 0.4:6, the resulted co-doped PANI (PANI_H0.4D6) exhibited a maximum yield of 70.09%. Thermogravimetric analysis (TGA) results illustrated that there were four weight loss stages in the co-doped PANI. These weight losses were resulted from the evaporation of moisture, HNO₃, DBSA, and PANI respectively. TGA results also indicated that approximately 10.04 and 3.32 repeating units of PANI were doped with one HNO₃ molecule and one DBSA molecule in the co-doped PANI_H0.3D7, respectively. Fourier transform infrared (FTIR) results showed that the absorption peaks of the ?C═C? and ?C_aromatic?N? stretching vibrations in the emeraldine salt (ES) PANI were all shifted to the lower wavenumbers than those in the emeraldine base (EB) PANI. It was worth noting that the morphology of PANI was strongly affected by polymerization conditions.     

Morphological characterization and kinetics study of polyaniline film formation by emulsion polymerization

The kinetics and morphology of polyaniline film prepared by using ammonium persulfate (APS) as oxidant and dodecylbenzoyl sulfonic acid (DBSA) as both emulsifier and dopant were studied in this paper. The kinetics of the formation of polyaniline film was determined by using the quartz crystal microbalance (QCM), and the film morphology was characterized by scanning electron microscopy (SEM). The reaction exhibited half-order kinetics with respect to APS concentration and first-order kinetics with respect to aniline concentration. The activation energy is 41.15 kJ/mol, and the growth rate of PANI film increased with increasing temperature and decreased with increasing concentration of DBSA.     

Fabrication of DBSA‐doped polyaniline nanorods by interfacial polymerization

An interfacial polymerization was used to fabricate dodecybenzenesulfonic acid (DBSA)‐doped polyaniline (DBSA‐PANI) nanorods with diameter range from 40 nm to 1 μm. The molar ratio of aniline to ammonium peroxydisulfate (APS), the concentrations of DBSA and reaction temperature had an effect on the morphology and size of products. It was found that lower concentration of DBSA and lower temperature will be helpful to the formation of rod‐like PANI nanostructures with a relative small diameter. UV–vis and FTIR measurements were used to characterize the chemical structure of the obtained samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

DBSA掺杂聚苯胺的制备、表征及其导电性

采用过硫酸铵(APS)为氧化剂在十二烷基苯磺酸(DBSA)微胶束中化学氧化制备纳米棒状聚苯胺;DBSA既起乳化剂也起掺杂剂的作用。制备的掺杂聚苯胺用红外光谱(FTIR)、紫外光谱(UV-vis)、X-射线衍射(XRD)和扫描电镜(SEM)进行了表征;透射电镜(TEM)下首次观察到了聚苯胺的有序排列结构,晶面间距为5.99 Å。考察了掺杂剂/苯胺、氧化剂/苯胺的摩尔比和反应温度、时间等对聚苯胺电导率影响,最高电导率达到了0.72 S/cm。透射电镜怎能看到5.99     

Synthesis,characterization, and comparative study of conducting polyaniline/lead titanate and polyaniline–dodecylbenzenesulfonic acid/lead titanate composites

To study the effect of a surfactant on the properties of polyaniline (PANI)/metal oxide composites, PANI/lead titanate (PbTiO₃) composites were synthesized with different weight percentages (10, 20, 30, 40, and 50 wt %) of PbTiO₃ in both the absence and presence of dodecylbenzenesulfonic acid (DBSA) by the polymerization of aniline with ammonium persulfate as an initiator. The structural characteristics and stability, surface characteristics, and electric properties of PANI/PbTiO₃ and PANI–DBSA/PbTiO₃ were studied and compared. The interfacial interactions and thermal stability of these composites were characterized with X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermogravimetry techniques. The results indicate significant changes in the physicochemical properties of the composites with the incorporation of DBSA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

酸浓度和聚合周期对DBSA掺杂PANI结构性能的影响

采用循环伏安法在镀金PET膜上聚合得到了十二烷基苯磺酸(DBSA)掺杂的聚苯胺(PANI)膜,通过对比不同条件下所得PANI膜的红外光谱、微观形貌、循环伏安特性、X射线衍射谱图和紫外-可见光-近红外反射光谱,研究了DBSA浓度和聚合时间对PANI结构和性能的影响。结果表明,DBSA可以通过电化学聚合过程掺入PANI分子链,由于长链烷基的增容作用,PANI呈纤维状。电化学聚合过程中,随DBSA浓度增大,PANI成核速率增加,易形成片状致密结构,造成PANI膜结晶度升高、离子空间位阻变大,且膜的光谱反射率逐渐降低。随聚合时间的增加,PANI表面形貌逐渐变差,出现团簇现象,成核速率逐渐增加,PANI纤维横向生长形成带状。     

Synthesis and characterization of polyaniline nanorods as curing agent and nanofiller for epoxy matrix composite

Novel PANI nanorods with average diameter of 21-53 nm and length of 0.5-1 μm were synthesized by dispersion polymerization method. The morphology of obtained PANI nanorods was significantly dependent on the type of salt, stirring, and polymerization temperature. Dispersion polymerization with FeCl₃ produced longer nanorods than ammonium persulfate (APS) and magnetic stirring decreased the length of nanorods. While the average diameter of PANI nanorods decreased with increasing reaction temperature, the electrical conductivity dropped considerable at high polymerization temperature due to the increment of insulating emeraldine base. Dynamic differential scanning calorimetry (DSC) study showed that the heat of cure was independent of heating rate. On the contrary, the heat of cure was proportional to the content of PANI nanorods as a role of curing agent. Isothermal DSC study revealed that the cure behavior of LCE/PANI nanorod system was an auto-catalyzed reaction. Thermogravimetric analysis (TGA) indicated that the thermal stability of cured LCE/PANI nanocomposite was significantly dependent on the PANI nanorod composition. In addition, the electrical conductivity of LCE/PANI nanocomposite materials was higher than that of conventional epoxy composites. Therefore, PANI nanorods played a role of curing agent owing to the existent amine group and acted as reinforcing filler for cured LCE nanocomposites.     

Facile preparation of conductive paint made with polyaniline/dodecylbenzenesulfonic acid dispersion and poly(methyl methacrylate)

We investigated an easy way to prepare industrially a conductive paint made with polyaniline (PANI)/dodecylbenzenesulfonic acid (DBSA) dispersion and poly(methyl methacrylate) (PMMA) in organic media. First, water‐dispersible PANI doped with DBSA was chemically synthesized with aniline sulfate using ammonium persulfate in water, and the resulting PANI/DBSA was readily extracted from the reaction medium with a mixture of toluene and methyl ethyl ketone (MEK) (toluene:MEK = 1:1 (v/v)), which is useful for industrial applications. The obtained PANI/DBSA organic dispersion was mixed with PMMA organic solution to give the corresponding PANI/DBSA conductive paint containing PMMA. A film prepared with the resulting PANI/DBSA conductive paint was found to possess relatively good conductivity and low surface resistivity for a conductive paint utilized for an electrostatic discharge even at low PANI/DBSA content in the PANI/DBSA–PMMA composite film (the conductivity and the surface resistivity were 9.48 × 10^?4 S cm^?1 and 3.14 × 10⁶ Ω cm^?2, respectively, when the feed ratio of PANI/DBSA:PMMA was 1:39 (w/w)). Furthermore, it was found that the conductivity of the film composed of PANI/DBSA–PMMA composite can be readily and widely controlled by the PANI/DBSA content of the composite or by the amount of DBSA used during the PANI/DBSA synthesis. The highest conductivity of PANI/DBSA–PMMA composite film (7.84 × 10^?1 S cm^?1) was obtained when the feed ratio of PANI/DBSA:PMMA was 1:4 (w/w). Copyright © 2007 Society of Chemical Industry     

Effect of dodecyl benzene sulfonic acid on the preparation of polyaniline/activated carbon composites by in situ emulsion polymerization

Polyaniline (PANI)/activated carbon (AC) composites are prepared by in situ emulsion polymerization using dodecyl benzenesulfonic acid (DBSA). DBSA can play a role as both surfactant and dopant in the process of PANI synthesis. The effect of DBSA on the preparation of PANI/AC composites is investigated in this research. For this purpose, the composites are prepared in micellar solutions with various concentrations of DBSA. It is confirmed using X-ray diffraction (XRD) analysis and Fourier-transform IR (FT-IR) spectroscopy that DBSA actually participates in the PANI doping process. The PANI doped with DBSA (DBSA-PANI) covering the AC surfaces is observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties of the composites are studied by cyclic voltammetry (CV). The composites show different values of specific capacitance, which was found to be a function of DBSA concentration. The composite prepared in 0.045 M DBSA solution shows the highest specific capacitance (115.2 F g^?1) among the prepared composites. The doping level of DBSA-PANI is increased with the concentration of DBSA in solution.     

Growth mechanism of transparent and conducting composite films of polyaniline

Composites of polyaniline (PANI) with various polymeric matrices as substrates were synthesized by means of diffusion–oxidation of aniline swollen polymeric matrices with FeCl₃ as oxidizer. The conductivity at room temperature, transmittance at 400–800 nm, stability in air, and morphology of PANI composite films depend on the polymerization time, concentration of FeCl₃, and substrate used. A maximum conductivity at room temperature and the highest transmittance at 500–800 nm can be achieved of 10^?1 S/cm and 70–80%, respectively. The growth mechanism of PANI composite films has been discussed. © 1993 John Wiley & Sons, Inc.     

Polymerization of anilinium/DBSA in the presence of clay particles: Catalysis and encapsulation

This paper describes polymerization of anilinium‐DBSA complex to PANI‐DBSA (DBSA doped polyaniline) in an aqueous dispersion in the presence of mica or talc clays. It is found that the clay presence significantly accelerates the polymerization kinetics by metal ions, such as Fe⁺² ions, present in the clays. Polymerization occurs preferentially on the clay particles' surface, causing their encapsulation with PANI‐DBSA shells. Further coating with PANI‐DBSA takes place on the already coated particles with thin PANI‐DBSA shells by an autoacceleration effect of anilinium‐DBSA polymerization by PANI. It is suggested that the catalytic/autoacceleration effect dominating in the coating process of clay particles with PANI‐DBSA can be extended to other particle/coating systems, which are already under investigation.     

Optimum reaction conditions for polypyrrole film deposition with some iron(III) compounds

The optimum reaction conditions for the deposition of smooth conductive polypyrrole (PP) films were monitored using a quartz crystal microbalance technique. This is for oxidative polymerization of pyrrole with some iron(III) compounds. The FeCl₃ · 6H₂O/pyrrole system in aqueous solution at 20 ± 0.5°C was examined in some detail. The effect of the initial molar ratio of the reactants on the yield and the growth rate of the PP film deposition was studied. The optimum molar ratio was found to be approximately 2.4 ± 0.1. A comparison between the growth rate of the PP films was made when different iron(III) compounds were used. The rate is shown to be affected by the nature of the anions in these compunds.     

聚苯胺/nano-ATO导电复合材料的原位聚合与表征

用原位聚合法,以十二烷基苯磺酸(DBSA)/HC l混酸为掺杂剂,过硫酸胺(APS)为氧化剂,制备了聚苯胺/掺锑二氧化锡(ATO)导电复合材料。探讨了ATO用量对导电复合材料电导率的影响。在n(苯胺)∶n(APS)∶n(DBSA)=1∶1∶0.7,m(ATO)∶m(苯胺)=0.1∶1时,复合材料室温25℃的电导率最高可达8.35 S/cm,比通常方法合成的聚苯胺和nano-ATO的电导率分别提高约1至2个数量级。通过FTIR、XRD、SEM和TEM对目标物进行了表征,结果表明,苯胺优先在ATO纳米粒子表面聚合,形成聚苯胺包覆ATO的导电复合材料。     

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。     

Effects of the loading and polymerization temperature on the capacitive performance of polyaniline in NaNO3

Polyaniline (PANI) synthesized by a potentiostatic method at 4 °C in 1 M HNO₃ with the polymerization charge density equal to/less than 0.45 C cm⁻² was demonstrated to exhibit ideally capacitive characteristics (i.e. high reversibility and high-power property) with a high specific capacitance of 210 F g⁻¹ for the application of electrochemical supercapacitors in NaNO₃. Influences of the polymerization charge density (i.e. the polymer loading) and the polymerization temperature on the capacitive characteristics of PANI films compared by both cyclic voltammetry and charge-discharge technique were reasonably correlated with their structural properties examined by X-ray photoelectron spectroscopy (XPS). The highest specific capacitance of a PANI film polymerized at 4 °C was attributed to its lowest density of structure defects. The surface morphology of these PANI films was examined by a scanning electron microscope (SEM).     

Pyrrole polymerization on polyimide surfaces creates conductive nano-domains

Oxidative polymerization of pyrrole on the surface of polyimide (PI) films was demonstrated to generate uniform, adherent coatings consisting of polypyrrole (PPy) electro-active nano-domains. This polymerization was carried out in aqueous methanol solution with FeCl₃ as oxidant/dopant. Model kinetic reactions carried out by hydrogen Nuclear Magnetic Resonance (¹H NMR) spectroscopy using ammonium persulfate (APS) as oxidant found evidence for an increase in the polymerization rate of pyrrole in the presence of a molar excess of PI. Attempts to identify changes to the PI chemical structure during pyrrole polymerization were investigated by high-resolution carbon ¹³C NMR spectroscopy and Infrared Attenuated Total Reflection (IR-ATR) spectroscopy. No differences were observed in concentrated D₂SO₄ solutions by NMR. However, IR-ATR noted a shift to lower wavenumbers of the PI carbonyl band and a higher wavenumber shift of the aromatic ether band. The morphology of PPy-coated PI films was analyzed by atomic force microscopy (AFM). The average size of PPy nanospheres was in the range of 20 nm with narrow distribution and was found to increase with reaction time.     

In situ polyaniline film formation using ferric chloride as an oxidant

In situ polyaniline (PANI) films were grown from an aqueous hydrochloric acid solution on glass substrates via the chemical oxidation of aniline using hydrated ferric chloride, FeCl₃.6H₂O (FC). The effect of initial molar ratios of FC/aniline on the yield of PANI films was monitored using the quartz crystal microbalance technique. The morphology of the resultant polymer film and powder was examined using scanning electron microscopy. It was found that the film possesses a porous character; however, the polymer powder consists of small particles with interconnected nanofibers. The polymer powder formed in the bulk was characterized using the energy dispersive analysis of X-ray, the X-ray diffraction, and the thermal gravimetric analysis. A comparison between the PANI produced from FC and ammonium peroxydisulfate was considered and discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

乳液聚合法制备聚苯胺/聚乙烯醇电致变色材料

以十二烷基苯磺酸(DBSA)为掺杂剂,在非有机溶剂的两相体系中以聚乙烯醇(PVA)为成膜助剂,采用现场乳液聚合法合成了可直接用于制备电致变色膜的聚苯胺(PAn)/PVA乳液。研究了PVA含量、苯胺(An)与DBSA的量比、氧化剂过硫酸铵(APS)与An的量比及反应温度对膜的电致变色性、导电性的影响。实验结果表明:在w(PVA)=4 3%、n(An)∶n(DBSA)∶n(APS)=0 86∶1∶0 86、反应温度为8℃时,所制得的PAn/PVA乳液可直接制成具有良好电致变色性的自支撑膜(电致变色响应时间小于0 5s,电导率可达2 69×10-4S/m)。     

Effect of aniline‐formaldehyde resin on the reduced conjugation length of doped polyaniline: Thermal studies

A linear aniline‐formaldehyde resin (AF) complexed with different acids was successfully synthesized with the traditional way of polymerizing a novolac‐type phenolic resin. When the AF(DBSA)_1.0 (AF complexed with only HDBSA (n‐dodecyl benzene sulfonic acid)) was blended with PANI(DBSA)_0.5 (polyaniline doped only by HDBSA, the T_gs (glass transition temperatures) of the polyblends decreased with PANI(DBSA)_0.5, indicating the presence of the compatibility that can alter the doping condition of PANI(DBSA)_0.5 by changing the conjugation length. In the polyblend system, it was also confirmed when the polyblend of 50/50 showed a higher residue weight than the rest of polyblends after being heated up to 450°C. The λ_max of UV–vis spectra of PANI (DBSA)_0.5 demonstrates a red shifts indicating the secondary doping effect (increasing conjugation length) was recovered when PANI(DBSA)_0.5 was mixed with less than 50% of AF(DBSA)_0.5 (HCl)_0.5. Similar phenomenon of red shift was found for the blended samples of PANI(DBSA)_0.5/AF(DBSA)_1.0 at high temperatures. IR spectra revealed an alkyl affinity interaction is present between PANI(DBSA)_0.5 and AF(DBSA)_1.0 at room temperature and a strong and free localized polaron band appeared at high temperatures due to the recovery of secondary doping. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2120–2128, 2007