Influence of doped polyaniline on the interaction of Pu/PAni blends and on its microwave absorption properties

In this work, the influence of polyaniline (PAni) doped with both camphorsulfonic acid (PAni‐CSA) and dodecylbenzenesulfonic acid (PAni‐DBSA) on polyurethane (PU)/PAni blends was studied by rheological and morphological analyses. The effect of doped polyaniline on the attenuation of incident microwave radiation, in the frequency range from 8.0 to 12.0 GHz, was also investigated. The complex viscosity (η*) of PAni‐DBSA blends is observed to vary more significantly as a function of resting time than PAni‐CSA blends. This behavior is attributed to a better dispersion of PAni particles into the matrix on account of the presence of smaller agglomerates, as observed by optical and electron microscopy. However, this behavior has not been determinant on microwave absorption by the blends, with those that contain PAni‐CSA showing higher attenuation values. Copyright © 2007 John Wiley & Sons, Ltd.     

Determination of percolation threshold electroactivity and phase behavior study on conducting blends of thermotropic polyesters and polyaniline

The new thermotropic polyester/polyaniline (PIn/PAni) blends have been prepared by solution blend of synthesized liquid crystalline poly[4,4′‐bis (ω‐alkoxy) biphenylisophthalate]s having four and six methylene units in spacer (PI4 and PI6) with PAni doped with camphorsolfonic acid (CSA). The percolation threshold electroactivity of prepared blend films has been determined by cyclic voltammetry. The effect of the PAni concentration, solvent nature and polyester structure on the electroactivity of the blends has been investigated. The extremely low percolation threshold of prepared PIn/PAni‐CSA blends from dimethylformamide (DMF) and m‐cresol solution was 3% weight of PAni‐CSA. The amount of conducting polymer necessary to retard the formation of the liquid crystalline (LC) phase is up to 45% by weight. Phase behavior studies by differential scanning calorimetry and polarizing microscopy show that blends with 45% of conducting polymer are both liquid crystal and conductive. The morphology of the blends has been investigated by scanning electron microscopy. Copyright © 2004 John Wiley & Sons, Ltd.     

Development of environmental friendly castor oil‐based waterborne polyurethane dispersions with polyaniline

This study describes the fabrication and characterization of castor oil‐based waterborne polyurethane/polyaniline (COWPU/PAni) conducting polymer blend films. The COWPU synthesized from isophorone diisocyanate was reacted with castor oil to form prepolymers, which were chain extended by reacting it with N‐methyldiethanolamine. Quaternization and self‐emulsification including deionized water followed in COWPU dispersions. Also, COWPU/PAni hybrid dispersions were synthesized with 2, 4, and 6 wt% of PAni–dodecyl benzene sulfonic acid to make different conductive composites. The outcome of COWPU/PAni was characterized by Fourier transform infrared spectrometer, differential scanning calorimeter, thermogravimetric analysis, dynamic mechanical and thermal analyzer, and scanning electron microscopy analysis. According to Fourier transform infrared spectrometer analysis, hydrogen bonding appears between –NH of PAni and C?O of COWPU. Meanwhile, incorporating PAni can improve the thermal stability of COWPU. The resulting COWPU/PAni conducting blend films can be used as antistatic and anticorrosive coating materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Antistatic thermoplastic blend of polyaniline and polystyrene prepared in a double-screw extruder

One of the major aims of research on intrinsically conducting polymers (ICP) is the production of blends combining the processing properties of thermoplastic polymers with the conductivity of conducting polymers. The main problem in applying ICP on a large scale in the plastic industry is the impossibility of plasticizing these polymers under heat and shear. However, the use of functionalized acids improves the thermal stability and processability of conductive polymers. In this work the doping process was carried out during processing, also denoted as “reactive processing”. This procedure reduces the number of steps to obtain the final product, PS/SBS/PAni. Blending of polystyrene with dodecylbenzenosulfonic acid doped polyaniline was carried in a double-screw extruder using the block copolymer of styrene and butadiene, SBS, as compatibilizer. A conductive thermoplastic (σ = 10⁻⁶-10⁻² S cm⁻¹) was obtained in the form of ribbons, which were used to evaluate the thermal, mechanical, morphological and electrical properties. We used SBS as compatibilizer and different formulations were tested according to a statistical response surface method. The mechanical and electrical properties of these thermoplastic blends are adequate for antistatic applications.     

A conductive elastomer based on EPDM and polyaniline: II. Effect of the crosslinking method

Electrically conductive heterogeneous binary polymer blends based on ethylene-propylene-diene-monomer (EPDM) and polyaniline (PAni) were prepared in a Haake Rheocord 90 rheometer, coupled with an internal mixer (counter rotating cam rotors) using different amounts of PAni doped with dodecylbenzenosulfonic acid (DBSA). Blends were crosslinked using two methods: (i) phenolic resin (SP-1045) as crosslinking agent and (ii) electron beam irradiation. The last method avoids the interference of the acid dopant in the crosslinking process and produces blends with higher conductivity.     

Processing, characterization and properties of conducting polyaniline-sulfonated SEBS block copolymers

Incorporation of polyaniline (PAni) into thermoplastic elastomers can be used to produce materials that potentially combine the good mechanical properties and processability of thermoplastic elastomers with electrical, magnetic and optical characteristics of PAni. In this work, a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene copolymer (SEBS) was chemically modified by grafting a sulfonic group onto the chain backbone in order to promote higher levels of compatibility between the thermoplastic elastomer and polyaniline. The sulfonation process was performed by reacting SEBS with acetyl sulfate. Infrared spectroscopy and titration were used to monitor the amount of sulfonic groups successfully grafted on SEBS. Mechanical tests performed in sulfonated SEBS showed that sulfonation levels lower than 15% did not reduce substantially the mechanical properties of SEBS. PAni doped with dodecylbenzenesulfonic acid (PAni·DBSA), used in the preparation of the blends, was prepared by the “in situ doping polymerization” method. PAni·DBSA was then blended in solution with SEBS having different levels of sulfonation. The introduction of sulfonic group into the structure of SEBS improved coulombic interactions between the phases in the blend and enhanced compatibility. As a consequence, higher values of electrical conductivity (measured by the four-probe method) were achieved in blends with sulfonic groups grafted onto polymer chains. Concentrations as low as 20 wt% of PAni were able to lead to electrical conductivities of PAni·DBSA/sulfonated SEBS blends close to 1.2 S/cm. Optical micrographs of the blends showed that PAni·DBSA/sulfonated SEBS microstructure is composed of a very disperse group of small conducting particles. This type of microstructure would then be responsible for the enhanced electrical conductivity and low percolation threshold of PAni·DBSA/sulfonated SEBS, when compared to PAni·DBSA/SEBS blends.     

Extrinsic and intrinsic structural change during heat treatment of polyaniline

HCl doped polyaniline (PAni) was synthesized electrochemically and heat treated at 150 °C, 200 °C and 250 °C for 30 min in vacuum. Different intrinsic and extrinsic structural changes due to heat treatment were determined from XRD, TGA, FT-IR, conductivity and solubility measurement. When HCl doped PAni is subjected to heat treatment, different changes are taking place in the system like doping, dedoping (extrinsic), oxidation, chain scission, cross-linking and changes in crystal structure (intrinsic). Mechanism for doping, dedoping, oxidation, chain scission and cross-linking is proposed.     

Structural effects of dopants and polymerization methodologies on the solid‐state ordering and morphology of polyaniline

The solid‐state three‐dimensional ordering of polyaniline–dopant complexes was investigated with four structurally different sulfonic acid dopants. The doped materials were produced in three different ways: polyaniline emeraldine base doped with sulfonic acid (aqueous route), in situ polymerization at the organic–water solvent interface (interfacial route), and in situ polymerization in organic and aqueous solvent mixtures (bilayer route). p‐Toluenesulfonic acid (PTSA), 5‐sulfosalicilic acid (SSA), camphorsulfonic acid (CSA), and dodecylbenzene sulfonic acid (DBSA) were employed as dopants. The conductivity of the aqueous‐route samples showed 10 and 100 times higher conductivity than the interfacial and bilayer routes, respectively. WXRD studies suggested that the crystallinity of the doped samples was dependent on both the structure of the dopants and the polymerization techniques. DBSA increases the polyaniline interplanar distance and produced highly crystalline materials via the aqueous and bilayer routes but failed with the interfacial route because of poor solubility in water. CSA, PTSA, and SSA produced highly crystalline samples by the interfacial route but failed with the aqueous (except for CSA) and bilayer routes. SEM analysis revealed that the doped materials of the interfacial route had excellent continuous morphology and uniform submicrometer‐size particle distributions in comparison with those of the aqueous and bilayer routes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1321–1331, 2005     

XPS研究聚苯胺的竞争掺杂行为

采用X射线光电子能谱（XPS）方法对不同反应体系下化学合成的聚苯胺（PANI）的结构和掺杂状况进行了研究。发现盐酸（HCl）掺杂的聚苯胺在样品后处理过程中易发生脱掺杂行为;在十二烷基苯磺酸钠（SDBS）和盐酸共存体系下合成聚苯胺时,对阴离子DBS-和Cl-发生竞争掺杂行为。结果表明DBS-与带正电荷聚苯胺链结合,起到了掺杂和诱导聚苯胺可溶性的作用,它的N1s和S2p谱图与单独采用十二烷基苯磺酸（DBSA）掺杂聚苯胺的谱图相似。但SDBS-HCl复合体系比单独采用DBSA体系更为有利。     

Synthesis of core‐shell silver–polyaniline nanocomposites by gamma radiolysis method

Core‐shell silver (Ag)–polyaniline (PAni) nanocomposites have been synthesized by the in‐situ gamma radiation‐induced chemical polymerization method. Aqueous solution of aniline, a free‐radical oxidant, and/or silver metal salt were irradiated by γ‐rays. Reduction of the silver salt in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline to polyaniline. The resultant Ag‐PAni nanocomposites were characterized by using different spectroscopy analyses like X‐ray photoelectron, UV–visible, and infrared spectroscopy. The optical absorption bands revealed that the bands at about 400 nm are due to the presence of nanosilver and the blue‐shifted peak at ～ 555 nm is due to the presence of metallic silver within the PAni matrix. X‐ray diffraction pattern clearly indicates the broad amorphous polymer and the sharp metal peaks. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the composites have a higher degradation temperature than polyaniline alone. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5741–5747, 2007     

PAni/Si/G/C复合材料的制备及电化学性能

通过球磨及高温固相法制得了Si/C复合材料,并氧化合成聚苯胺包覆于硅碳复合材料的表面. 采用XRD、SEM、红外和热重分析观察复合材料形貌、分析样品结构,循环伏安法和充放电测试表征PAni/Si/G/C电极电化学性能. 结果表明,PAni/Si/C复合材料表面覆盖了较为完整的片层状结构的聚苯胺膜,可逆容量高达784 mAh.g^-1,50次周期循环后,嵌锂容量保持在690 mAh?g-1.     

Lightweight electromagnetic shields using optimized polyaniline composites in the microwave band

A genetic algorithm (GA) was used to optimize a multilayer electromagnetic shield of polyaniline (PANI)–polyurethane (PU) conducting composites in the microwave band. First, the electronic properties of freestanding films with different mass fractions of polyaniline were studied. A very low percolation threshold (0.2%) was found, with a maximum of conductivity of 10⁴ S/m. Second, the electromagnetic shielding effectiveness of the films were investigated in the X and Ku bands (8.2–18 GHz), showing an attenuation increase of 1–40 dB with the mass fraction of polyaniline in the blends. Then, the electromagnetic shielding properties of multi‐layered PAni–PU composites were investigated in order to obtain an attenuation superior to 40 or 80 dB, depending on the application. To improve the performances of the electromagnetic shields, three‐layered PAni–PU composites were made, using an optimization method. The intrinsic physical parameters of the composites were used as a database for the optimization calculation. The optimization results showed that materials with a thickness of <500 µm could answer many industrial or military shielding applications. As the electronic properties can be tuned easily with the mass fraction of polyaniline in the blends, conducting multi‐layered composite materials can be made following the results of the optimization. Their electromagnetic shielding effectiveness was measured, showing good agreement between the measurements and modeling. These results demonstrated that the genetic algorithm allows us to conceive lightweight and high performance electromagnetic shields using intrinsically conducting polymers. The mass per unit of surface of the shield was <200 g/m², giving potential applications in the aeronautics domain. Copyright © 2007 John Wiley & Sons, Ltd.     

Analytical performance characteristics of nanoelectrospray emitters as a function of conductive coating

As miniaturization of electrospray continues to become more prevalent in the mass spectrometry arsenal, numerous types of conductive coatings have been developed with miniaturized electrospray emitters. Different conductive coatings have different properties that may lead to differences in analytical performance. This paper investigates and compares the analytical properties of a series of applied conductive coatings for low-flow electrospray ionization developed in this laboratory vs. commercially-available types. Evaporated graphite is thoroughly compared with commercially available polyaniline (PANI) coated emitters and metal coated emitters. Each set of emitters was investigated to determine various performance characteristics, including susceptibility to electrical discharge in both positive and negative ionization modes, as well as emitter reproducibility and generation of a standard curve to determine each emitter coating's limit of detection and limit of quantitation. Furthermore, evaporated graphite and polyaniline coated fused silica capillaries were investigated to determine which coating is more stable over long-term analyses and during electrical discharge.     

Polyaniline/thermoplastic polyurethane blends: Preparation and evaluation of electrical conductivity

Conducting polymer blends whose undiluted components have different properties are promising materials for specific applications and have attracted interest in recent years. The aim of this study was to obtain and evaluate the electrical conductivity of polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA)/polyurethane thermoplastic (TPU) blends. The PAni.DBSA was synthesized from DBSA-aniline (DBSAn) salt through an emulsion polymerization in tetrahydrofurane (THF) or in the presence of polyurethane thermoplastic solution, resulting in pure PAni.DBSA or PAni.DBSA/TPU blends. Blends of PAni.DBSA/TPU were also prepared through casting, at room temperature, after dissolving both components in THF as a common solvent. The insulator-conductor transition was very sharp and the percolation threshold was lower than 2.7 wt% of PAni.DBSA. The electrical conductivity of PAni.DBSA/TPU blends, prepared by both methods, reached maximum values at a PAni.DBSA concentration of 40 wt%, close to the value observed for the undiluted conducting polymer. However, for a PAni.DBSA content lower than 30 wt%, the electrical conductivity was dependent on the blend preparation method. Blends were characterized by infrared spectroscopy, thermogravimetric analysis (TG) and optical microscopy. The electrical conducting characteristics of the PAni.DBSA/TPU blends prepared using different procedures indicate a high potential for their successful application in electrical processes.     

Zn-Al-[V_(10)O_(28)]~(6-)双层氢氧化物掺杂对LY12铝合金表面溶胶-凝胶涂层性能的影响

采用共沉淀法制备Zn-Al-[V10O28]6-双层氢氧化物(以下简称LDH-V),研究不同添加浓度(0.0、0.25×10-3、0.75×10-3、1.5×10-3、3.0×10-3mol·L-1)的LDH-V对LY12铝合金溶胶-凝胶涂层形貌、耐蚀性的影响.采用扫描电子显微镜(SEM)和傅里叶变换红外(FTIR)光谱研究LDH-V对涂层形貌和结构的影响.运用中性盐雾实验对涂层进行耐蚀性评估.利用电化学方法对涂层在0.05 mol·L-1的NaCl溶液中的腐蚀行为进行研究.探讨加入LDH-V后溶胶-凝胶涂层的耐蚀机理.结果表明,一定量LDH-V的加入不仅可以提高溶胶-凝胶涂层的耐蚀性能,还可对涂层被破坏区域进行自修复,起到延缓铝合金基体腐蚀的作用.然而,当LDH-V的添加溶度超过一定值时,会破坏涂层的完整性并降低涂层的腐蚀防护性能.实验结果表明LDH-V最佳的添加浓度为1.5×10-3mol·L-1.     

Doping of polyaniline with polymeric dopants in solid state,gel state and solutions

Polystyrene with different degrees of sulfonation was empolyed as a polymeric dopant for polyaniline. The purpose of using a polymeric dopant is to avoid the migration of a small molecule dopant to increase stability of the doped complex. We applied the polymeric dopant to polyaniline in three different ways: in solid state, in solution and in gel state. In solid state, the conducting form was achieved only through a novel thermal doping method with the increase in temperature and pressure. In solution, the doping process was shown to be dependent on the nature of the solution and also on the molecular weight of the polymer. In the gel form of polyaniline, a polymeric dopant with a surprising low degree of sulfonation was found to be successful in the doping process.     

掺杂态聚苯胺的性能及其防腐应用研究进展

聚苯胺具有良好的导电性和独特的掺杂-解掺杂特性,成为近年来备受关注的导电高分子材料,其特有的抗划伤、抗点蚀和钝化性能使其在金属防腐领域拥有巨大的应用前景。聚苯胺结构中苯环的存在,使得其分子链具有较大刚性,而分子间氢键又导致其难溶、难熔、可加工性能较差,严重制约了聚苯胺的应用。掺杂过程能有效改善聚苯胺的某些性能,或赋予其新的功能,扩展聚苯胺的应用。本文综述了聚苯胺的掺杂方式、掺杂机理、聚苯胺防腐材料的制备方法,以及其在金属防腐领域的应用,展望了聚苯胺的研究和应用前景。     

Enhancing corrosion resistance of zinc-filled protective coatings using conductive polymers

Organic coatings containing zinc are amply used for the protection of metals, particularly steel structures. Ways to reduce the zinc content in the coating materials are sought for environmental and financial reasons. Our previous work (Kohl, Prog Org Coat 77:512–517, 2014; Kohl and Kalendová, Mater Sci Forum 818: 171–174, 2015a) suggested that one of the options consists in the use of conductive polymers in the formulation of the zinc coatings. The benefits of conductive polymers include nontoxicity, high stability, electric conductivity and redox potential. Previously we focussed on the effect of conductive polymers added to the organic coatings so as to complete the zinc volume concentration to 67%. The anticorrosion efficiency of the organic coatings was found to improve with increasing polyaniline phosphate or polypyrrole concentrations. Zinc content reduction in the system, however, did not attain more than 5%. The present work focusses on systems where the organic coatings are prepared with zinc having a pigment volume concentration PVC = 50%. Zinc content reduction in the system attains up to 20%. This work examines the mechanical and anticorrosion properties of the organic coatings with reduced zinc contents. The present work was devoted to the feasibility of using of conductive polymers in the formulation of coatings with reduced zinc contents. The conductive polymers included polyaniline, polypyrrole and poly(phenylenediamine); these were synthesised and characterised using physico-chemical methods. Polyphenylenediamine as a potential corrosion inhibitor has not been paid adequate attention so far. Subsequently, organic coatings with reduced zinc contents and containing the pigments at 0.5, 1 and 3% volume concentrations were formulated. The coatings were subjected to mechanical tests and accelerated corrosion tests to assess their mechanical and corrosion resistance. The corrosion resistance of the organic coatings was also studied by linear polarisation. The results of the mechanical tests, accelerated corrosion tests and linear polarisation measurements indicate that the organic coating properties get affected by the conductive polymer type as well as by the pigment volume concentration. The important finding is that the use of conductive polymers in coatings with reduced zinc contents was beneficial in all cases.     

Facile synthesis of the structural hierarchy in chrysanthemum–snowball-like self-organized polyaniline

A facile synthesis of the “chrysanthemum–snowball”-shaped polyaniline (PAni) has been prepared by using self-assembly polymerization of the host–guest monomeric inclusion complex of β-cyclodextrin (β-CD) with aniline. The amount of the monomer complex plays a role as a structural regulator during fabrication of the inclusion polymer as chrysanthemum–snowball structure/nanorods via intermolecular interactions such as: hydrogen bonding between β-CD and PAni, π–π interactions and cooperative interaction between PAni with FeCl₃ in an aqueous medium. The microstructure and morphology of the resulting materials were investigated by using various analytical techniques such as Fourier transform infrared, wide-angle X-ray diffraction, small-angle X-ray scattering, field emission scanning electron microscopy and transmission electron microscopy. After observing the growth process, a tentative mechanism is proposed to elucidate the formation of the PAni hierarchical structures.     

Self-supported bacterial cellulose polyaniline conducting membrane as electromagnetic interference shielding material: effect of the oxidizing agent

Conducting bacterial cellulose (BC) membranes coated with a high proportion of polyaniline (PAni) were prepared through in situ oxidative polymerization of aniline on the surface of the BC in the presence of acetic acid as the protonating agent. The effect of two different oxidizing agents, ammonium persulfate (APS) or iron(III) chloride (FeCl₃), on the mechanical performance, electrical conductivity, crystallinity, morphology and ability to absorb the electromagnetic radiation was investigated. BC/PAni membranes prepared with FeCl₃ displayed higher conductivity and better mechanical performance than those observed for pure BC or the BC/PAni membranes prepared with APS. Experiments related to the electromagnetic absorbing properties revealed that BC/PAni membranes prepared with FeCl₃ also present improved absorbing properties in the frequency range of 8–12 GHz. The morphology of the membranes, observed by field emission gun-scanning electron microscopy, is strongly affected by the oxidizing agent. Whereas the BC/PAni membranes prepared with APS present PAni nanoparticles attached on the fiber surface as agglomerates in the form of flakes, those prepared with FeCl₃ display a uniform and smooth coating of PAni on the BC fibers as hierarchical mode.