Flexible polyaniline

Flexible polyaniline having excellent mechanical properties (e.g., elongation at break = 41% and tensile strength = 1.8 kg cm^?2) was prepared by electrochemical reduction of ordinary polyaniline in organic solvents. The flexibility is directly related with the polymer morphology which was definitely affected by the nature of electrolyte anion. Perchlorate or tetrafluoroborate anion were found suitable to obtain flexible polyaniline. At the same time, it is essential that the polymer so prepared should be reduced (undoped) in some suitable organic solvents before making a flexible free standing film.     

Synthesis of poly(o‐phenylenediamine) nanofiber with novel structure and properties

The poly(o‐phenylenediamine) (PoPD) was synthesized from the monomer o‐phenylenediamine in various organic solvent medium viz. dimethyl sulfoxide (DMSO), N,N‐dimethyl formamide (DMF) and methanol using ammonium per sulfate as a radical initiator. The structure just like polyaniline derivative with free ?NH functional groups of the synthesized polymers confirmed by various standard characterizations was explained from the proposed polymerization mechanism. All the synthesized polymers were completely soluble in common organic solvent like DMSO and DMF because of the presence of polar free ?NH functional groups in its structure. The formation of polymer nanofiber by reverse salting‐out process was confirmed, and the synthesized polymer in DMSO medium was the best polymer in terms of nano‐morphology as well as conducting properties. Interestingly, the average DC conductivity of undoped polymer film was recorded as 2.21 × 10^?6 Scm^?1 because of induced doping through self charge separation. Moreover, the conductivity of the polymer film was further increased to 1.16 × 10^?3 Scm^?1 after doping by sulfuric acid. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of carbon black content on electrical and microwave absorbing properties of polyaniline/carbon black nanocomposites

Carbon black coated with polyaniline, forming a core-shell structure, was synthesized by in situ polymerization at different carbon black contents (5-30 wt.%) and introduced into epoxy resin to be a microwave absorber. The spectroscopic characterizations of the formation processes of polyaniline/carbon black composites were studied using Fourier transform infrared, ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. Microwave absorbing properties were investigated by measuring reflection loss in the 2-18 and 18-40 GHz microwave frequencies range using the free space method. The results showed that a wider absorption frequency range could be obtained by adding different carbon black contents in polyaniline.     

Circularly Polarized Luminescence of a Stereogenic Curved Paraphenylene Anchoring a Chiral Binaphthyl in Solution and Solid State

A curved stereogenic [6]paraphenylene ([6]PP), anchoring a chiral binaphthyl scaffold at 7,7’-positions, was prepared and investigated for its properties as a solid-state circularly polarized luminescence (CPL) dye. X-ray analysis revealed a helically twisted structure of PP units induced by axial chirality of binaphthyl framework. The curved [6]PP exhibits fluorescence in powder and polymethyl methacrylate (PMMA) film as well as solution. A significant increase in quantum yield was observed for a non-fluid PMMA film owing the suppression of the molecular motion. The g_CPL values of the dye in solution and as PMMA film were almost the same (4.3–4.4×10⁻³) and lager than that in powder. TD-DFT calculations in the excited state suggest that the exciton can be delocalized into a twisted PP unit to produce a larger magnetic transition dipole moment.     

Synthesis and Properties of Composite Polyaniline–Nafion Films on Platinum

Information on the synthesis of a polyaniline film on platinum covered with a Nafion film is obtained. The effect of electrochemical conditions on the synthesis is studied. The relationship between these conditions and properties of obtained composite polyaniline–Nafion films is revealed. It is established that on platinum covered with a Nafion film in certain electrochemical conditions in a polyaniline solution there occurs the formation of a composite polyaniline–Nafion film. The polyaniline in the film mainly retains its individual properties. It is demonstrated that the mechanism of the synthesis of polyaniline in the composite film substantially differs from that in the case of the formation of a film on platinum.     

Synthesis and characterization of aluminum–polyaniline thin films and membranes

Polyaniline (PAni) films of different intrinsic oxidation states, including emeraldine salt, emeraldine base and leucoemeraldine base, were synthesized. Free‐standing membranes and thin film bilayers of aluminum–polyaniline were fabricated by magnetron sputter deposition of aluminum onto polyaniline films. Aluminum–polyaniline samples were analyzed by transmission electron microscopy (TEM) to investigate the microstructures of specimens, including cross‐sectional TEM micrographs of the metal‐polyaniline interfacial structure not previously reported in the literature. Auger electron spectroscopy (AES) and X‐ray photoelectron spectroscopy (XPS) were employed to study the chemical bonding and interaction between deposited aluminum and polyaniline at the interface. Results indicated that the intrinsic oxidation state of the polyaniline influenced the chemistry of the aluminum–polyaniline interface. Distinct interaction between aluminum and polyaniline in the emeraldine salt‐form was observed. However, there was no evidence of direct interactions of the aluminum with emeraldine base and leucoemeraldine base polyaniline. Copyright © 2005 John Wiley & Sons, Ltd.     

Polyaniline thin film optical waveguides for integrated optics and VLSI prepared by vacuum evaporation technique

Polyaniline is emerging as an important polymer material which offers challenging opportunities for both fundamental research and new technological applications in waveguides. Metal doped polyaniline has been prepared initially in the form of powder by a solution growth technique. The emeraldine salt with doped metal was also prepared by solution growth technique. This powder was used for vacuum evaporation on optically flat glass substrate. The dark green doped (Fe, Al) polyaniline thin films were prepared by vacuum evaporation technique (10^?4 torr). Deposited waveguide thin films have been characterized structurally, using X‐ray diffraction (XRD), optically etc. Effective refractive index of the thin film waveguide was also calculated theoretically and experimentally. Waveguide parameters, namely refractive index, propagation loss and depth of vacuum deposited polyaniline thin films optical waveguide have been determined. The optical spectra and structure and waveguide parameters of vacuum deposited polyaniline thin films are strongly affected by the type of doping. It is possible to reduce the losses by addition of Fe to the vacuum deposited polyanine thin film and modify the effective refractive index (O_eff) according to particular requirements. Results are compared with the results in the literature. Copyright © 2002 John Wiley & Sons, Ltd.     

Conductive polymers as a new type of thermoelectric material

Thermoelectric properties were investigated for the films of electrically conductive doped polyanilines. The thermoelectric performance, evaluated by thermoelectric figure-of-merit (ZT = T (S² σ) / κ), of various protonic acid-doped polyaniline bulk films was found to depend on the electrical conductivity σ of the film. Thus, the higher the electrical conductivity, the higher the figure-of-merit is, because the thermal conductivity κ of polyaniline films does not depend on the electrical conductivity. Among the conductive bulk films of polyaniline, the highest figure-of-merit (ZT = 1 × 10⁻⁴) was observed for (±)-10-camphorsulfonic acid (CSA)-doped polyaniline in an emeraldine form (σ - 188 S cm⁻¹) at room temperature. The multilayered film, composed of electrically insulating emeraldine base layers and electrically conducting CSA-doped emeraldine salt layers, exhibited 6 times higher ZT at 300 K than that of a bulk film of CAS-doped polyaniline, showing the highest ZT value of 1.1 × 10⁻² at 423 K. Stretching of the CAS-doped polyaniline film also increased the figure-of-merit of doped polyaniline films along the direction of the stretching.     

Electrochemical behavior of polyaniline films in acetonitrile

The electro-oxidation and electroreduction behavior of polyaniline films in acetonitrile in the absence and presence of added acid or base were investigated using cyclic voltammetry. A general mechanism is proposed that enables the interpretation of the electroactivity loss and the catalytic and autocatalytic properties of the film. The electroactivity loss was found to be a reversible phenomenon which is accelerated in alkaline solutions through deprotonation. Electroactivity was recovered when the electroinactive films were reduced in an acidic solution. The films that lose their electroactivity on electro-oxidation were found to be conducting, and various cation radicals in the structure are believed to be responsible for this nonprotonic conductivity. The proton content of the polyaniline film was found to be crucial in determining its electrochemical and physical properties. Autocatalysis was detected when protons were produced electrolytically in situ during electropolymerization.     

聚苯胺黄嘌呤氧化酶电极的生物电化学活性

用电化学方法将黄嘌呤氧化酶固定在聚苯胺中以制成聚苯胺黄嘌呤氧化酶电极。该电极呈现典型的酶催化反应动力学特性。且具有快速的生物电化学响应。固定化黄嘌呤氧化酶的表观米氏常数为21×10^-^6mol.dm^-^3, 最适pH为8.4,酶催化反应的活化能为85.1kJ.mol^-^1。酶电极具有较高的稳定性。使用聚苯胺黄嘌呤氧化酶电极能可靠地测定较低的底物浓度, 如2×10^-^6mol.dm^-^3黄嘌呤。     

The carbon nanotubes-polyaniline composites and their effect on catalytic properties of deposited catalysts

Composites of functionalized single-wall carbon nanotubes and polyaniline are deposited onto electrodes by in situ electrochemical polymerization. Their electrochemical behavior and differential capacitance are studied by cyclic voltammetry, electrochemical impedance spectroscopy, and chronovoltamperometry. The differential capacitance of the composite electrode exceeds that of pure polyaniline film deposited onto electrode, which can be explained by the nanotubes’ loosening effect on the polyaniline structure. The composite-electrode capacitance is as large as 1000 F g⁻¹ or higher. Thus obtained composite films were used as a support for deposited platinum-ruthenium catalyst. The Pt-Ru structure and catalytic properties in the methanol oxidation reaction are studied. It is shown that the specific current of methanol oxidation at Pt-Ru is larger by a factor of 7–15 than those measured when pure polyaniline, pure carbon nanotubes, or standard Vulcan XC-72 carbon black are used as supports. It is found that the catalytic activity is the same for all studied supports, provided the current is reduced to the unit of Pt-Ru true surface area. Thus, the observed large catalytic effect is associated with the structure and high dispersivity of the electrodeposited metals incorporated to the single-wall carbon nanotubes-polyaniline composite.     

Thermodynamic and structural properties of water adsorbed film on MgO (100) ionic surface

We have investigated by adsorption isotherms and neutron diffraction measurements, respectively the thermodynamic and structural properties of water physisorbed film on MgO (100) powder. Thanks to a high temperature thermal treatment, under vacuum, our MgO powder samples are characterized by a highly homogeneous (100) MgO surface. We have determined the structure of the (2D) water film physisorbed on such an ionic surface. This one is a commensurate P(2×3) structure which is very similar to the (110) planes of ice-VII. Recall that ice VII, which is stable at very high pressure, is characterized by a quite large density (d = 1.6).     

GAS SEPARATION PROPERTIES OF FREESTANDING FILM OF POLYANILINE

The gas separation properties of free- standing film of polyaniline (PANI) for gas pairs of He/N2, H_2/N_2. CO_2/N_2 and CO_2/CH_4 at room temperature were measured as a function of the protonation state. Variation of the gas permeabilities coefficient of PANI with an insulator to metal transition upon the protonation processes was observed, which might be due to a change in both gas solubility coefficient and diffusion coefficient with the protonation state.     

循环伏安法的电扫描方式对苯胺聚合产物形貌影响的观察

在含有0.2 mol.L-1苯胺的0.5 mol.L-1H2SO4溶液中,以扫描速度50 mV.s-1,扫描电位为-0.1~0.9 V,采用循环伏安法(CV),在金属Ti基体上,通过控制扫描方式分别得到了颗粒状、纤维状及管-片状的苯胺聚合产物,分析了形成不同形貌聚苯胺的原因,并通过扫描电子显微镜(SEM)、循环伏安法和电化学阻抗谱(EIS)对不同形貌聚苯胺的结构和性能进行了表征.结果表明,不同形貌聚苯胺的形成是由于聚苯胺的成核及生长模式不同,而无论何种形貌的聚苯胺膜都具有很大的比表面积和良好的导电性能,其中,管-片状聚苯胺的膜层阻抗最小,导电性能最好.     

Platinum-modified polyaniline/polysulfone composite film electrodes and their electrocatalytic activity for methanol oxidation

The polyaniline/polysulfone (PAN/PSF) composite films were prepared by electropolymerization, and then platinum was deposited into this composite film to obtain the platinum-modified polyaniline/polysulfone(Pt/PAN/PSF) composite film electrodes. Their component, morphology and structure were characterized by FTIR spectra, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that the composite film has a bi-layer structure with asymmetrical pores, and the platinum particles are homogeneously dispersed in the modified film electrodes. The cyclic voltammetry and electrochemical impedance spectroscopy techniques were applied to investigate the electrochemical properties and the electrocatalytic activity of the modified film electrodes, which show a promotive action for methanol oxidation and the methanol oxidation under a diffusion-controlled process.     

Two‐Dimensional Mesoscale‐Ordered Conducting Polymers

Despite the availability of numerous two‐dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale‐ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assemblies in different dimensions to achieve 2D conducting polymer nanosheets with structural ordering at the mesoscale. The supramolecular assemblies of amphipathic perfluorinated carboxylic acids and block co‐polymers serve as 2D interfaces and meso‐inducing moieties, respectively, which guide the polymerization of aniline into 2D, free‐standing mesoporous conducting polymer nanosheets. Grazing‐incidence small‐angle X‐ray scattering combined with various microscopy demonstrates that the resulting mesoscale‐ordered nanosheets have hexagonal lattice with d‐spacing of about 30 nm, customizable pore sizes of 7–18 nm and thicknesses of 13–45 nm, and high surface area. Such template‐directed assembly produces polyaniline nanosheets with enhanced π–π stacking interactions, thereby resulting in anisotropic and record‐high electrical conductivity of approximately 41 S cm^?1 for the pristine polyaniline nanosheet based film and approximately 188 S cm^?1 for the hydrochloric acid‐doped counterpart. Our moldable approach creates a new family of mesoscale‐ordered structures as well as opens avenues to the programmed assembly of multifunctional materials.     

Facile Synthesis of Free‐Standing Polymer Brush Films Based on a Colorless Polydopamine Thin Layer

A free‐standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface‐initiated atom transfer radical polymerization (ATRP) of 2‐hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free‐standing PHEMA brush film (1.5 cm × 1.5 cm). Because the cross‐linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross‐linking the polymer brushes. The free‐standing film thicknesses of ≈16–75 nm are controlled by simply changing the ATRP reaction time. The results show that the free‐standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.

     

基于超氧化物歧化酶/氧化锌的超氧离子传感器

利用物理气相沉积法制备了纳米氧化锌(Nano-ZnO) 膜, 通过扫描电子显微镜(SEM)、紫外-可见分光光度法(UV-Vis)、X 射线衍射(XRD)及电化学等方法测定了其物理化学性质. 实验结果表明, 该Nano-ZnO 膜是具有多晶六边形纤维锌矿结构的多孔纳米膜, 微粒直径在 50～100 nm, 室温禁带宽度3.37 eV. 采用浸渍法将超氧化物歧化酶(SOD)直接修饰于 Nano-ZnO 膜上, 制备了SOD 修饰电极(SOD/ZnO). 通过交流阻抗法(EIS)及循环伏安法(CV)证明了SOD能稳定地吸附在多孔ZnO膜上, 并实现了直接电子传递; 紫外-可见及红外光谱研究证明吸附在ZnO膜上的蛋白质保持了良好的生物催化活性, 并成功地构建了第三代超氧离子(O2-)生物传感器. 这种生物传感器有较宽的线性范围(氧化电流: 0.24~180×10-6 mol/L, 还原电流: 0.12~250×10-6 mol/L)、较低的检测限(氧化电流: 2×10-7 mol/L, 还原电流: 1×10-7 mol/L)、较快的响应时间(4 s)以及较好的稳定性.     

Water absorption in polyaniline emeraldine base

Atomistic classical molecular dynamics simulations have been used to investigate the water absorption behavior of polyaniline emeraldine base. Results derived from simulations, which were performed considering polymeric systems with different concentrations of water (3%, 10%, 15%, 20%, 50%, and 100% w/w), have been compared with experimental evidences obtained for both powder and films. Calculation of the Hildebrand solubility parameters explains not only the insolubility of polyaniline in water but also the requirements, in terms of intermolecular interactions, needed by solvents to be compatibles with this polymer. The maximum content of absorbed water predicted for hygroscopic polyaniline is 15% w/w. The effects of the absorbed water in both the organization and conformation of the polymer chains have been examined at the microscopic level by analyzing the microstructures derived from simulations, while the role of the moisture in the morphology of powder and film samples has been investigated using atomic force microscopy. The overall of the results provides a complete and understandable view of the polyaniline·water interactions, and explains the influence of the water molecules in the structural properties of the polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1322–1331, 2011     

β-萘磺酸掺杂聚苯胺纳米粒子的固相反应法制备及其表征

利用固相反应法制备了 β 萘磺酸掺杂的聚苯胺纳米粒子 ,并以红外光谱 (FTIR) ,扫描电子显微镜(SEM) ,透射电镜 (TEM) ,X 射线衍射 (XRD)以及粉末微电极等测试方法对其进行了表征 .结果表明 ,固相反应法合成的 β 萘磺酸掺杂聚苯胺粒子直径为 30～ 5 0nm ,聚苯胺分子链排列有序 ,晶化率较好 .粉末微电极的循环伏安测试表明 ,β 萘磺酸掺杂聚苯胺有较好的电化学活性 .