Preparation and characterization of conducting polymer/silver hexacyanoferrate nanocomposite

In this work, we present an alternative route to prepare silver hexacyanoferrate(II)/polyaniline (PANI) composite thin films. Differently from the electrochemical method, used to synthesize the conducting polymer film on a electrode surface, this new chemical route makes use of dialysis membrane as a solid support to synthesize the silver hexacyanoferrate(III) compound, and subsequently uses this composite membrane as oxidizing agent to polymerize the aniline monomer. The spectroscopic (UV-vis and IR region) and electrochemical characterization (cyclic voltammetry) indicates that the polymeric composite remains optically active and conductive. The X-ray analysis shows that the composite membrane/Ag₃[Fe_III(CN)₆] has an crystalline structure that can be assigned to the Ag₃[Fe_III(CN)₆] structure, and after reaction with aniline solution it became less crystalline. Additionally the SEM measurements shown that the reaction of silver ions with hexacyanoferrate(III) across the membrane results in a well defined and aliened Ag₃[Fe_III(CN)₆] crystals and when this crystalline compound reacts with aniline monomer silver wire of 100 nm of diameter by 6 μm longer are formed together with the conducting polymer polyaniline/Ag_x[Fe_II(CN)₆] composite.     

导电聚合物微米/纳米结构的制备和性质

文章综述了导电聚合物微米／纳米结构(微米管、纳米管、纳米线和微米球等)近几年来所取得的研究进展．重点介绍了三种制备方法(模板合成、无模板法、电纺丝技术)和导电聚合物微米／纳米管的电学、力学、热学、磁学等性能．     

In situ surface modification of natural fiber by conducting polyaniline

Newly modified biofibers made up of kenaf fibers (KF) and conducting polyaniline (PANI) were successfully prepared via in situ polymerization. Several characterization methods were done to elucidate the interaction between the KF surfaces and the in situ polymerized PANI. The PANI coated KF (KF/PANI) achieved new electronic properties, without sacrificing its mechanical properties and natural fiber characteristic. Initial mercerization on the KF yielded better PANI coated fibers compared to the untreated KF. Fiber bundle tensile test on the untreated KF/PANI revealed a drop in the unit break of about 48% compared to the untreated neat KF. Meanwhile, the mercerized KF/PANI showed reduction of about 17% compared to the uncoated mercerized KF. The mercerized KF/PANI exhibits polaronic transitions, existence of favorable IR peaks and Raman scattering, enhanced DC conductivity, and better morphological characteristic as a result of the in situ PANI coating. Such electronically modified natural fibers could be suitable as green conducting fillers in composites to replace other synthetic fibers.     

Composites of multiwall carbon nanotubes and conducting polyaniline: Bulk samples and films produced from a solution in chloroform

Multiwall carbon nanotubes and conducting polyaniline, doped with dodecylbenzenesulfonic acid, are blended by employing the solubility of both materials in chloroform. Pellets are made by pressing the dried powder of the obtained composite, and films by sedimentary deposition onto a plastic substrate. In these composites, the advantageous properties of carbon nanotubes can be utilized in fully conducting bulk and planar structures while the strong decrease of the conductivity of doped polyaniline at low temperatures is simultaneously suppressed. The nanotube content in pellets can be as high as 40% by weight, and this wide range leads to a control over the shape and magnitude of the conductivity versus temperature curves. As the nanotube content grows, the temperature dependence of the conductivity becomes less steep, which is similar to the effect of annealing temperature on the conductivity of certain polycrystalline graphene films. In our case, this change is most likely caused by the increase of the density of highly conducting channels and not by homogeneous delocalization effects.     

Microwave absorption behavior of a polyaniline magnetic composite in the X-band

The development of nanosized materials is a subject of considerable interest both for understanding of the fundamental properties of magnetic materials for new technological applications. Polyaniline, composites Fe₃O₄/(PANI) with conducting, magnetic and electromagnetic properties with different amounts of Fe₃O₄ were successfully prepared. The samples were structurally characterized by scanning electron microscopy (SEM), X-ray diffraction and transmission electron microscopy (TEM) and magnetically, with a superconducting quantum interference device (SQUID) magnetometer. In order to explore microwave-absorbing properties in X-band, the composite nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite. Microwave behavior with different Fe₃O₄/(PANI)-epoxy resin ratio was studied using a microwave vector network analyzer (VNA) in the range 7.5 to 13 GHz. For a constant thickness of 1.5 mm, absorption increases with the magnetite contents in the composites and in the oriented samples by the application of a magnetic field.     

Polymerization of aniline on bacterial cellulose and characterization of bacterial cellulose/polyaniline nanocomposite films

Bacterial cellulose/polyaniline nanocomposite film was prepared by the chemical oxidative polymerization of aniline with bacterial cellulose. Polyaniline conducting polymer nanocomposite films with bacterial cellulose fibers was prepared and characterized. In nanocomposite film, the bacterial cellulose was fully encapsulated with polyaniline by direct polymerization of the respective monomers using the oxidant and dopant. These bacterial cellulose/polyaniline nanocomposite films materials exhibited the inherent properties of both components. The deposition of a polyaniline on the bacterial cellulose surface was characterized by SEM. XPS revealed a higher doping level of the nanocomposite films doped with p-TSA dopant. From the cyclic voltammetry results, the polyaniline polymer was thermodynamically stable because redox peaks of electrochemical transitions in the voltagrams were maintained in bacterial cellulose/polyaniline nanocomposite films.     

Electrochemical synthesis and characterization of a new conducting polymer: Polyrhodanine

An antimicrobial drug, rhodanine (Rh), was electrochemically polymerized on a Pt electrode using cyclic voltammetry (CV). The high quality and homogeneous polyrhodanine (pRh) films with a dark-purple color were obtained. The chemical structure characterization was investigated by Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy techniques. Further, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques used to investigate thermal properties of the film. It is found that thermal stability of pRh films is relatively high. It is also observed that tetrahydrofurane (THF) and N-methyl-2-pyrrolidone (NMP) are good solvents for the polymer.     

Freestanding conducting polyaniline film for the control of electromagnetic radiations

Electromagnetic interference is pollution generated due to dense nature of circuitry in electronic devices and is required to be control at its source. Polyaniline is an environmentally stable conducting polymer which can be cast as thin film, which can replace the corrosive metals as a shield for the control of electromagnetic radiations. In this communication we discuss our results on the preparation of flexible freestanding conducting polyaniline film of varied thickness using either p-toluenesulphonic acid (PTSA) or camphor-10-sulphonic acid as a primary dopant and 4-chloro-3-methyl phenol (CMC) as a secondary dopant. The resulting films were characterized by conductivity, scanning electron micrograph and shielding effectiveness measurements (SE). The SE measurements were carried out using co-axial transmission line method in the frequency range of 0.1–1000 MHz. We noticed that only the change of 2% in the shielding effectiveness of these films over the period of 3 years indicating the environmental stability of polyaniline films.     

萘磺酸掺杂对纳米管结构聚苯胺低温电阻率的影响

通过研究用自组装法制备的萘磺酸掺杂的纳米管结构聚苯胺(苯胺与萘磺酸的摩尔比分别为1∶025,1∶05,1∶1,1∶2,1∶3)的电阻率温度依赖关系(测量温区为80—300K),仔细分析聚苯胺的结构形貌特征,提出了变程跳跃隧道穿透混合模型:认为在萘磺酸掺杂的纳米管结构聚苯胺样品中,跳跃和隧穿两种机制同时起作用,载流子沿纳米管传导是变程跳跃过程起主要作用,而载流子在纳米管之间的传导是隧穿过程起主要作用.实验结果表明,不同浓度的萘磺酸掺杂对样品的低温电阻率的影响很大,随着掺杂浓度增加,载流子传导所需克服的能垒C0迅速减小,当掺杂接近饱和时,C0不再减小.实验中还研究了不同形貌对电阻率的影响,结果表明样品中纳米管所占比例的增大有利于载流子传导 关键词： 聚苯胺 纳米管 低温电阻率     

Far Infrared Spectra of Ammonia-Boron Trifluoride: NH3BF3 and ND3BF3

Abstract

Spectra of polycrystalline samples of NH₃BF₃ and ND₃BF₃ at 300 K and 98 K have been recorded in the frequency range 20-400 cm^?1. Isotopic frequency ratios are used to interpret the observed features in terms of the known molecular and crystal structures.     

Use of Cu dopant and it's doping effects on polyaniline conducting system in water and tetrahydrofuran

The structural modification and properties of polymeric materials are of utmost importance in deciding their applications. In the present study, the synthesis of polyaniline (PANI) has been carried out via chemical oxidation in acidic medium by potassium-dichromate and the yield of synthesized polyaniline was found to be 75-80%. The copper per chlorate tetrabenzonitrile salt (CuClO₄·4BN) used for chemical doping in synthesized polyaniline is stable in organic solvent like acetonitrile (AN) and benzonitrile (BN). The effect of Cu⁺¹ oxidation state (dopant) in polyaniline has been characterized by FTIR. Electrical and dielectric measurements show the decrease in the intensity of the Cu⁺¹ salt signal and the appearance of a radical signal due to the formation of oxidative coupled in polymeric species. Electrical and dielectric properties of doped polyaniline samples show significant changes due to the effect of dopant (CuClO₄·4BN). It is observed that the conductivity is contributing both by formation of ionic complex and particularly dominated by electronic due to the mobility of charge carriers along the polyaniline chain.     

过苯胺黑聚合物的双极化子态

利用改进的Ginder-Epstein模型研究聚苯胺黑的双极化子态,给出其键序波幅、芳环扭角、电子能级、理论吸收谱和电荷分布,并与极化子进行对比.结果发现双极化子激发能为3.08 eV,晶格驰豫宽度涉及12格点与极化子相当;键交错驰豫深度大约为极化子的2倍,畸变中心芳环扭角高达68.35°大于极化子中心扭角的2倍.两个能隙态几乎简并,吸收谱低能峰为1.6 eV.     

Comparative impact of doping nano-conducting polymer with carbon and carbon oxide composites in alkyd binder as anti-corrosive coatings

This study concentrated on producing anticorrosive coating depending on alkyd resin blended with polyaniline-carbon allotropes composites as filler. Polyaniline (PANI) and its composites were produced by doping of PANI with the carbon allotropes (graphene and multi-walled carbon nanotubes) and carbon-oxide allotropes (graphene oxide and multi-walled carbon nanotubes oxide) in different ratios through in situ chemical polymerization. The morphology of PANI and its composites were examined by transmission electron microscope (TEM), which proved that PANI composites appeared as a shell layer in core/shell structure with various overlay thickness depending on the adsorption type for polyaniline. The performance of the prepared coatings in cabinet salt agrees with electrical conductivity values where the best PANI/composite in conductivity value is the most efficient as an anti-corrosive coating.     

过苯胺黑聚合物的双极化子态

利用改进的Ginder-Epstein模型研究聚苯胺黑的双极化子态, 给出其键序波幅、芳环扭角、电子能级、理论吸收谱和电荷分布,并与极化子进行对比。结果发现双极化子激发能为3.08eV, 晶格驰豫宽度涉及12格点与极化子相当;键交错驰豫深度大约为极化子的2倍,畸变中心芳环扭角高达68.35°大于极化子中心扭角的2倍。两个能隙态几乎简并,吸收谱低能峰为1.6eV。     

Electrical resistance response of polyaniline films to water, ethanol, and nitric acid solution

<正>This paper reports on electrical resistance vs.aging time for the response of polyanihne films under exposure to water,ethanol and nitric acid(HNO_3) solution.Camphor sulfonic acid-doped polyanihne films were prepared by a "doping-dedoping-redoping" method,the morphology and microstructures of the films were characterized by a scanning electron microscope and an x-ray diffractometer,the electrical resistance was measured by a four-probe method.It was found that a lower amount of water molecules infiltrating the film can decrease the film's resistance possibly due to an enhancement of charge carrier transfer between polyanihne chains,whereas excessive water molecules can swell inter-chain distances and result in a quick increase of resistance.The resistance of the film under exposure to ethanol increases and becomes much larger than the original value.However,HNO3 solution can decrease the film's resistance sharply possibly owing to doping effect of protonic acid.These results can help to understand the conduction mechanism in polyaniline films,and also indicate that the films have potential application in chemical sensors.     

Photophysical characteristics of polyaniline with photochromic azobenzene side groups

Photochromic characteristics and optical molecular reorientation in conducting polymer such as polyaniline derivatives containing photochromic azobenzene moieties (PAPNPAPOA) in side chain are studied. Changes in the UV—vis absorption, refractive index, thickness, contact angle and morphology of these films after irradiation of a linearly polarized light with a wavelength of 365nm are measured. The trans-cis isomerization of PAPNPAPOA is proved irreversible even after withdrawing the UV light for a long time. That the structure of main-chain attends by the trans-cis isomerization of side-chain is confirmed by the absorption and the solution colour during the UV irradiation. These effects are discussed by taking the trans-cis isomerization of azobenzene into consideration.     

Optical investigations of conducting polypyrrole under pressure

Abstract

The changes in the characteristics of vibrational and optical properties of the conducting form of polypyrrole under pressure is studied.     

Simultaneous numerical optimization of the mechanical and electrical properties of polyaniline coated kenaf fiber using response surface methodology: nanostructured polyaniline on natural fiber

Response surface methodology was used to simultaneously optimize the electrical and mechanical properties of newly developed conducting biofibers made up of kenaf fiber/polyaniline (KF/PANI). The effect of process parameters such as PANI amount (1–10 wt.%), dopant concentration (5–25 N), and molar ratio of aniline/oxidant solutions (0.5–1.5) were studied using Design of Experiment. Both of the responses (electrical conductivity and unit break) obtained a quadratic model. The experimental values were in good agreement compared to the optimized process. The scanning electron microscope images of the optimized sample revealed uniform PANI component on the KF with nanofibrillar features.     

A novel intrinsically proton conducting star-shaped imidazole terminated oligomers

In this paper, intrinsically proton conducting imidazole-terminated oligomers were synthesized by tethering imidazole units via flexible ethylene oxides (EO) chain onto 1,3,5-benzenetricarbonyl chloride (TMA). The structure of the resulting material was confirmed by FT-IR; ¹H-NMR spectrometer and compositions were obtained by elemental analysis. Thermogravimetry results showed that the materials are thermally stable up to approximately 160 °C. Differential scanning calorimeter studies were performed to study the influence of the length of EO units on the glass transition temperatures of the materials. The conductivity isotherms exhibit Vogel–Tamman–Fulcher behavior with a maximum proton conductivity of at 110 °C for TMA-(Peg₆₀₀-Imi)₃.     

高压下某些导电高分子色散关系的研究

利用晶格动力学方法,研究在高压下几种导电高分子具有不同晶格链时的色散关系及其曲线的变化.链间耦合作用的减弱使横波与纵波的ω差值相应增大,且在BZ边界处拉开一个间隙,这是维度作用的结果.