聚苯胺纳米点的氧化还原态与其库仑台阶效应

应用电化学恒电位法结合模板法制备聚苯胺纳米点阵列,导电原子力显微镜研究处于不同氧化还原态的聚苯胺纳米点的I～V特性,发现只有处于部分氧化态(导电态)的聚苯胺纳米点才出现库仑台阶效应,还原和全氧化态聚苯胺纳米点不显示库仑台阶.初步探讨了上述现象.     

静电纺丝法制备聚丙烯腈/聚苯胺复合纳米纤维及其表征

利用静电纺丝技术,以聚丙烯腈(PAN)和苯胺(ANI)为前驱物,用过硫酸胺(APS)溶液在低温下缓慢氧化聚合,制备了PAN/PANI复合纳米纤维,直径约500 nm.通过扫描电子显微镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)和激光拉曼(RAMAN)光谱仪等测试手段对材料的形貌和结构进行了表征.探讨了材料制备过程中影响纤维形貌、尺寸、均匀度的因素和PANI含量对复合纤维导电性能的影响,结果表明,PAN浓度、ANI的加入量和电压是影响纤维特性的主要因素;PANI在PAN基体中呈纳米尺寸分布,复合纳米纤维具有良好的导电性能,导电率可达10-2S/cm.     

不同质子酸掺杂对银/聚苯胺纳米复合材料结构和导电性的影响

利用紫外光作为辅助条件,在反胶束体系中采用一步双原位法合成了硝酸(HNO3)、对甲基苯磺酸(TSA)和5-磺基水杨酸(SSA)掺杂的银/聚苯胺(Ag/PANI)纳米复合材料.通过对复合材料进行红外光谱(FTIR)、紫外光谱(UV-Vis)、扫描电镜(SEM)、X射线衍射(XRD)和导电性能的测试,研究了不同质子酸对Ag/PANI纳米复合材料结构、形貌和导电性能的影响.测试结果表明,3种酸掺杂制备的Ag/PANI纳米复合材料均为聚苯胺包覆银粒子的核-壳结构.不同的质子酸掺杂会对Ag/PANI纳米复合材料的电性能有重要影响.在3种酸掺杂的复合材料中,TSA掺杂的复合材料的电导率最佳,为215.14 S·cm-1.     

碳纳米管网/聚苯胺复合材料的制备及电化学储能性能

分别采用粉末碳纳米管(CNT)和带连接点的碳纳米管网(CNTN)为模板,通过与聚苯胺(PANI)有限域聚合得到了CNT/PANI和CNTN/PANI 2种复合材料.采用透射电子显微镜和扫描电子显微镜对材料的形貌进行了表征,采用氮气吸附-脱附分析研究了材料的孔结构参数,运用双电四探针测试仪对材料的导电性能进行了测试,利用恒流充放电、循环伏安、循环寿命及交流阻抗等电化学测试手段表征了材料的电化学储能性能.结果表明,CNTN/PANI复合材料比CNT/PANI复合材料表现出更好的导电性能和电化学储能性能,其放电比容量可达到143.2 F/g(有机电解液).     

PANI/Ce(OH)3-Pr2O3·3H2O/NanoG复合材料制备与表征

开发了反胶束模板-原位聚合纳米复合法制备聚苯胺(PANI)/Ce(OH)3-Pr2O3·3H2O/石墨纳米薄片(NanoG)纳米复合材料的方法.膨胀石墨在乙醇水溶液中经超声处理制得石墨纳米薄片,以苯胺的氯仿溶液为油相,稀土金属离子Pr3+、Ce3+水溶液为水相,依靠表面活性剂十六烷基三甲基溴化铵(CTAB)自组装形成的反胶束为模板-制备PANI/Ge(OH)3-Pr2O3·3H2O/NanoG复合材料.利用红外光谱(FTIR)、扫描电镜(SEM)、透射电镜(TEM)和 X-射线衍射(XRD)对该复合材料进行了表征和分析,研究了其导电性能和热性能.结果表明,PANI/Ce(OH)3-Pr2O3·3H2O/NanoG复合材料各相分散均匀,稀土纳米粒子在体系中以棒状的形态分布.热重分析表明,该复合材料的热稳定性明显提高;导电性研究说明,石墨纳米薄片的特殊的结构(较大的径厚比)对其在聚合物基体中形成导电网络具有重要作用;PANI/Pr2O3-Ce(OH)3/NanoG纳米复合材料的渗滤阀值低于1.0wt%.     

尺寸可控的聚苯胺复合微球的电纺制备与表征

以十二烷基苯磺酸(DBSA)掺杂的导电聚苯胺与聚乙二醇(PEG)及Fe3O4的混合氯仿溶液,采用静电纺丝(spinning technology)方法制备含Fe3O4纳米颗粒的导电聚苯胺(PANI)/PEG/Fe3O4复合微球.SEM结果表明,电纺所得的PANI/PEG/Fe3O4复合微球结构依赖于PEG聚合物浓度、静...     

TiO2纳米微粒对聚苯胺性能的影响

纳米微粒具有量子尺寸效应, 其光、电、声及磁等方面的性能与常规材料有显著的不同, 其中以TiO2纳米微粒的电荷载体、光电活性中心、光学微腔和光电特性等特征[1,2]尤为引人注目. 导电聚合物的纳米复合材料是纳米材料的研究热点之一, 在导电材料、电流体和高密度信息存储材料等方面具有良好的应用前景[3]. 在导电聚合物中, 聚苯胺(PANI)因其具有较高的电导率, 原料便宜, 稳定性好而成为目前最有希望获得实际应用的导电聚合物[4～6]. 将纳米微粒和PANI制成复合材料, 其光电性能等与PANI相比均有所改变. 目前已相继有PANI-ZrO2, PANI-MnO2, PANI-SiO2纳米复合材料的报道[7,8], 而有关PANI-TiO2研究工作尚少见报道. 本文制备了PANI-TiO2纳米复合材料, 通过红外光谱、紫外可见光谱及透射电镜等探讨了复合材料的微结构及性能.     

静电纺丝制备荧光导电双功能复合纳米纤维及其表征

采用静电纺丝技术将导电聚苯胺(PANI)和铕/铽稀土配合物掺杂到高分子基质聚乙烯吡咯烷酮(PVP)中,制备出荧光导电复合纳米纤维。用扫描电镜(SEM)、荧光光谱仪(FL)、宽频介电松驰谱仪对荧光导电复合纳米纤维的性能进行分析,结果显示,在270nm紫外光激发下,铕系列与铽系列复合纳米纤维分别发出红光和绿光。同时,复合纳米纤维的电导率可以达到1.18×10~(-6) S/cm,两种复合纳米纤维同时具有优异的荧光性能及良好的导电功能。     

PANI导电水凝胶的制备及其进展

导电水凝胶结合了水凝胶和导电高分子电性能的独特特性,并且具有特殊三维网络结构。其中聚苯胺(PANI)由于其独特的导电性能得到了广泛应用,因此PANI导电水凝胶是导电水凝胶中研究最为广泛的。本文综述了PANI导电水凝胶的制备方法及其发展,详述了PANI导电水凝胶的四种制备方法:直接填充、原位聚合、化学交联和物理交联。其中,利用直接填充和原位聚合方法制得PANI水凝胶是较传统的方法,获得的PANI水凝胶是由绝缘的水凝胶组分和导电的PNAI组分组合在一起,电化学性能不高。化学交联法的应用提高了导电水凝胶的电化学性能,物理交联法应用较少。最后,对导电水凝胶材料的应用以及未来发展方向进行了展望。     

ZnO-聚苯胺复合膜的制备和性能研究

利用溶胶-凝胶法在Au膜、聚苯胺膜(PANI)和ITO(导电玻璃)基体上制备ZnO纳米微粒膜,初步研究了该微粒膜的形貌,结构和紫外-可见吸收等性质.结果表明,PANI的孔洞结构抑制了ZnO颗粒的团聚,因此,ZnO-PANI复合膜的紫外-可见吸收光谱和荧光光谱相对于ZnO-Au微粒膜有一定程度的蓝移.光电流谱研究同时表明,ZnO-聚苯胺复合膜有望在光电化学方面得到应用.     

Nanoscale measurements of conducting domains and current-voltage characteristics of chemically deposited polyaniline films

Spatial variations in electric conductivity and evolutions of band structures of polyaniline (PANI) films have been studied by use of a so-called current-sensing atomic force microscope (CS-AFM) or atomic force microscope current image tunneling spectroscopy (AFM-CITS). PANI films were deposited chemically onto indium-tin oxide- (ITO-) glass substrates, and their thickness and doping levels were controlled by polymerization and acid-doping conditions. The conducting uniformity of the PANI films depends on their doping level and thickness. Conducting domains were observed in fully doped PANI film, even when the bias voltage was reduced to as small as 30 mV. High current flowing regions gradually disappeared when conducting PANI films were partially dedoped. The point-contact current-voltage (I-V) characteristics of conducting tip-polymer/ITO systems were investigated on PANI films with different thickness and degree of doping. Various types of I-V curves representing metallic, semiconducting, and insulating states were obtained depending on the aggregation of polymer chains and doping level of the polymer film. The band gap energies (estimated from the I-V or dI/dV-V curves) of emeraldine base (EB) (undoped polyaniline) films are all higher than 3.8 eV, and a wide distribution of the band gap energies (0-1.1 eV and 0.75-1.8 eV for fully and partially doped PANI thin films, respectively) was found in a single polymer film.     

Effects of polymerization media on the nanoscale conductivity and current-voltage characteristics of chemically synthesized polyaniline films

A current sensing atomic force microscope (CS-AFM) was used to probe the conducting homogeneity and band structures of fully doped polyaniline (PANI) films prepared from in situ chemical polymerization/deposition of aniline on indium tin oxide in various inorganic acids. The charge transport properties of PANI films depend on the film thickness as well as polymerization medium. Fluctuations in conductivity are observed on all acid-doped PANI films and the conducting homogeneity was dependent on the film thickness: the conductivity of thick film is more uniform. The current-voltage (I-V) characteristics of all thick (>200 nm) films displayed a metal-like behavior and conductivity as high as 40 S/cm was detected in high conducting regions of film thicker than 400 nm. Whereas thin (<120 nm) films revealed insulating, semiconducting, and semimetal conducting, wide distribution in conductivity and interband distances (estimated from the I-V ordI/dV-V curves) was found. The interband distances is 0-1.35, 0-1.0, and 0-0.78 eV for thin PANI film prepared from HCl(aq), HClO(4)(aq), and H2SO4(aq), respectively. PANI film (260 nm) prepared from H2SO4(aq) revealed fiberlike morphology, and compared to PANI films prepared from HCl(aq) and HClO4(aq) with similar thickness, it has higher average nanoscale conductivity but lower bulk conductivity. This result could be direct evidence which supports that the bulk conductivity of PANI depended on the carriers hopping between the conducting domains.     

Study of a nanocomposite based on a conducting polymer: polyaniline

A simple way to obtain a conducting nanocomposite is described, and the conducting particles are characterized. Core-shell particles [polystyrene-polyaniline (PANI)] have been obtained by the dispersion process from three types of polystyrene latexes: a no-cross-linked core stabilized by a nonylphenolethoxylate (NP40) and two cross-linked cores stabilized by NP40 and a mixture NP40/Surfamid (a surfactant bearing an amide group). The surface of these particles has been extensively characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and scanning electron microscopy. A maximum coverage of 94% was obtained for the high PANI content as revealed by XPS analysis. A better coverage was obtained for the cross-linked polystyrene latex stabilized by the Surfamid. The amide group of this surfactant allows the H-bonding formation with the PANI backbone and, thus, improves the conductivity. It was shown that a uniform coverage of the core particles was not required to ensure a good conductivity.     

Development and application of patterned conducting polymer thin films as chemoresponsive and electrochemically responsive optical diffraction gratings

We describe the preparation of two-dimensionally patterned polyaniline (PANI) thin films via microtransfer molding and electropolymerization techniques. This procedure yields reproducible conducting polymer patterns with excellent feature periodicity, making them useful as diffraction gratings. The fabricated polymer gratings were characterized via tapping-mode atomic force microscopy. Spectroelectrochemistry was used to characterize the optical properties associated with various intrinsic PANI redox states. In accordance with the Kramers–Kronig relation for change-in-absorptivity and change-in-index-of-refraction, electrochemically induced changes in refractive index (detected via changes in diffraction efficiency) were observed to coincide with electrochemically-induced changes in the PANI electronic absorption spectrum. In addition, the higher oxidation states of PANI and the associated changes in refractive index proved accessible via chemical oxidation. Beyond the novelty of a chemically-switchable transmission grating, the response of this system points to the possibility of developing diffraction-based chemical sensing schemes.     

PANI Conductivity: A Dependence of the Chemical Synthesis Temperature

Summary: This work evaluated the influence of the synthesis temperature on the polyaniline (PANI) properties obtained by in-situ polymerization onto a poly (terephthalate) (PET) substrate. The residual mass of these syntheses was dried under vacuum, obtaining PANI powders for each temperature investigated. PANI/PET thin films and PANI powders were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis) and four-point probe techniques. The UV-Vis results showed that the synthesized PANI presents the emeraldine oxidation state. By means of XRD technique, it was possible to verify that the PANI powders present crystalline form. The AFM and FEG-SEM techniques showed that the decrease in PANI/PET and PANI powders electrical conductivity with increasing of the synthesis temperature is related to the polymeric aggregates morphology.     

Exploring the electronic and mechanical properties of protein using conducting atomic force microscopy

In interfacing man-made electronic components with specifically folded biomacromolecules, the perturbative effects of junction structure on any signal generated should be considered. We report herein on the electron-transfer characteristics of the blue copper metalloprotein, azurin, as characterized at a refined level by conducting atomic force microscopy (C-AFM). Specifically, the modulation of current-voltage (I-V) behavior with compressional force has been examined. In the absence of assignable resonant electron tunneling within the confined bias region, from -1 to 1 V, the I-V behavior was analyzed with a modified Simmons formula. To interpret the variation of tunneling barrier height and barrier length obtained by fitting with the modified Simmons formula, an atom packing density model associated with protein mechanical deformation was proposed and simulated by molecular dynamics. The barrier heights determined at the minimum forces necessary for stable electrical contact correlate reasonably well with those estimated from bulk biophysical (electroanalytical and photochemical) experiments previously reported. At higher forces, the tunnel barrier decreases to fall within the range observed with saturated organic systems. Molecular dynamics simulations revealed changes in secondary structure and atomic density of the protein with respect to compression. At low compression, where transport measurements are made, secondary structure is retained, and atomic packing density is observed to increase linearly with force. These predictions, and those made at higher compression, are consistent with both experimentally observed modulations of tunneling barrier height with applied force and the applicability of the atom packing density model of electron tunneling in proteins to molecular-level analyses.     

Synthesis and Characterization of PANI/ZnO Nanocomposites

This paper presents our results on the successful fabrication of HCl‐doped polyaniline (PANI)/ZnO nanocomposites via an electrochemical synthesis route. Different weight percents of ZnO nanoparticles were uniformly dispersed in the PANI matrix. The interaction between the dispersed ZnO nanoparticle and PANI was studied using X‐ray diffraction, ultraviolet–visible absorption spectroscopy, photoluminescence (PL) spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, thermogravimetry, and transmission electron microscopy. It is shown that the doping state of the PANI/ZnO nanocomposite is highly improved as compared to that of PANI. The dispersed PANI/ZnO nanocomposites exhibit enhanced PL behavior and thermal stability.     

Conducting polymer diffraction gratings on gold surfaces created by microcontact printing and electropolymerization at submicron length scales

Conducting polymer diffraction gratings on Au substrates have been created using microcontact printing of C18-alkanethiols, followed by electropolymerization of either poly(aniline) (PANI) or poly(3,4-ethylenedioxythiophene) (PEDOT). Soft-polymer replicas of simple diffraction grating masters (1200 lines/mm) were used to define the alkanethiol template for polymer growth. Growth of PANI and PEDOT diffraction gratings was followed in real time, through in situ tapping-mode atomic force microscopy, and by monitoring diffraction efficiency (DE) as a function of grating depth. DE increased as grating depth increased, up to a limiting efficiency (13-26%, with white light illumination), defined by the combined optical properties of the grating and the Au substrate, and ultimately limited by the loss of resolution due to coalescence of the polymer films. Grating efficiency is strongly dependent upon the grating depth and the refractive index contrast between the grating material and the surrounding solutions. Both PEDOT and PANI gratings show refractive index changes as a function of applied potential, consistent with changes in refractive index brought about by the doping/dedoping of the conducting polymer. The DE of PANI gratings are strongly dependent on the pH of the superstrate solution; the maximum sensitivity (DeltaDE/DeltapH) is achieved with PANI gratings held at +0.4 V versus Ag/AgCl, where the redox chemistry is dominated by the acid-base equilibrium between the protonated (emeraldine salt) and deprotonated (emeraldine base) forms of PANI. Simulations of DE were conducted for various combinations of conducting polymer refractive index and grating depth, to compute sensitivity parameters, which are maximized when the grating depth is ca. 50% of its maximum obtainable depth.     

Molecular dynamics simulation of surface morphology and thermodynamic properties of polyaniline nanostructured film

To develop predictive models in nanostructured films, there is an ongoing research to validate molecular dynamics (MD) simulation results with experimental data. The morphology and surface topography of polyaniline (PANI) nanostructured film coated on a TiO₂ nanocrystalline surface were investigated by scanning electron microscopy and atomic force microscopy, respectively. The atomistic model of the simulated PANI was generated using energy minimization with a condensed‐phase optimized molecular potential for atomistic studies force field function to reach a thermodynamic equilibrium state. Various parameters of PANI such as density, energy, cavity size, and free volume distributions are calculated. MD simulation has also been used to obtain specific volume (V) as a function of temperature (T). It is demonstrated that this V–T curve can be used to determinate glass transition temperature T_g, reliably. Although experimental data available for the PANI film are very limited, simulation results such as density and T_g are in good agreement with the experimental values reported in the literature. Comparison of the surface topography of PANI demonstrates a reasonable trend between atomic force microscopy image analysis and the MD simulation results at various temperatures. Copyright © 2014 John Wiley & Sons, Ltd.