Graphene oxide-filled conducting polyaniline composites as methanol-sensing materials

Polyaniline/graphene oxide (PANI/GO) composites were prepared by polymerization of aniline monomer in the presence of GO under acidic conditions. The synthesized samples were characterized by Fourier transform infra red spectroscopy, ultraviolet–visible absorption, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The direct current electrical conductivity of the composite was calculated by a four-probe technique. It is found that the conductivity dramatically increased to 241 S m^?1 for PANI/GO (5 wt%) composite at 110 °C compared to pure PANI (7.5 S m^?1). The composite material was investigated as a methanol vapour sensor and compared with pure PANI. The methanol-sensing characteristics of the prepared composite was monitored by measuring the change in electrical resistivity on exposure to methanol vapour at different concentrations. The resistivity of PANI increases on exposure to methanol vapour because of strong hydrogen bonding between methanol with the polymer chain. A density functional theory study was carried out to verify the proposed concept of hydrogen bonding between the polymer chains and methanol. The presence of GO in PANI/GO composite increases the sensitivity towards methanol as compared with the pure PANI.     

Novel conducting polyaniline copolymers of aniline and N-phenylglycine

N-phenylglycine was firstly applied to prepare the homopolymer and copolymers with aniline by chemical method using ammonium persulfate as oxidant. The products were characterized by Fourier transform infrared (FT-IR), Ultraviolet–visible (UV–vis) and X-ray diffraction (XRD). The conductivity was measured by two-probe method. The solubility increased while the conductivity and yield decreased with the increase in feed ratio of N-phenylglycine in the system.     

High-sensitivity, label-free DNA sensors using electrochemically active conducting polymers

Label-free oligonucleotide sensors that use a change in the electrode kinetics of the redox reaction of the negatively charged Fe(CN)(6)(3-/4-) redox couple to signal the formation of a DNA duplex with a surface-conjugated probe nucleotide are investigated. Electrochemically active conducting polymers (ECPs) can advantageously be used both as the active electrode and as the means of surface conjugation of the probe nucleotide. Here, we demonstrate that the sensitivity of the detection of the surface-complementary oligonucleotide can significantly be improved, into the low nanomolar range, by forming the ECP as a highly porous, very rough layer by growing it using electrochemical polymerization on a microelectrode. In comparison, smoother surfaces formed on macroelectrodes had detection sensitivity in the low micromolar range. We propose Donnan exclusion of the redox couple from small pores as the reason for the enhanced sensitivity. We discuss the effects using a simple patch model for the electrochemical kinetics and use the model to derive the equilibrium binding constant and binding kinetic rate constants for the surface hybridization reaction. We use the electrochemically active copolymer of pyrrole (Py) and 3-pyrrolylacrylic acid (PAA) [poly(Py-co-PAA)] as the sensing electrode and binding surface and measure the surface hybridization-induced changes in electrode kinetics of Fe(CN)(6)(3-/4-) by electrochemical impedance spectroscopy.     

导电聚苯胺乳胶纳米微球材料研究进展

本文综述了近年来国内外导电聚苯胺乳胶纳米微球材料的研究进展 ,对其主要分类、聚合原理、制备方法及特点进行了归纳和分析讨论 ,并对其在未来工业中的实际应用前景进行了展望。     

聚苯胺基导电可降解聚合物在组织工程中的研究进展

聚苯胺在电刺激下可调节细胞活性,促进细胞的黏附、生长和分化而备受关注。聚苯胺基导电可降解聚合物支架具有良好的电活性、生物相容性和可降解性,满足实际使用要求。研究支架降解速率与新组织形成之间的拟合是组织工程面临的挑战,对促进组织生长和愈合有着深远的意义。介绍了聚苯胺基导电可降解聚合物研究现状和发展方向,展望了导电可降解高聚合物在组织工程领域中的发展前景。     

新型智能材料:电活性聚合物的研究状况

电活性聚合物(electroactive polymer,EAP)是一种智能材料,具有特殊的电性能和机械性能。本文综述了不同类型电活性聚合物材料的国内外研究现状。按照作用机理的不同,电活性聚合物主要分为两大类:电子型和离子型。电子型EAP材料在直流电场作用下可产生诱导位移,但是需要较高的激励电场(>100V/μm);离子型EAP材料可以在较低电压下(1~2V)产生诱导弯曲位移,但是需要保持一定的湿润度,而且在直流电场激励下很难保持稳定的诱导位移。本文还介绍了电活性聚合物材料的应用领域和发展前景。由于其显著的电致伸缩响应,电活性聚合物被应用于驱动器和传感器,而且在仿生领域具有更广阔的应用。此外,透明度较高的EAP材料可被用于光学设备上。目前,电活性聚合物的应用还处于尝试阶段,但是,其独特的性能决定了这种材料具有不可估量的应用前景。     

Functionalised hybrid materials of conducting polymers with individual wool fibers

Composites of natural protein materials, such as merino wool, with the conducting polymers polypyrrole (PPy) and polyaniline (PAn) have been successfully synthesised. In doing so, hybrid materials have been produced in which the mechanical strength and flexibility of the fibers is retained whilst also incorporating the desired chemical and electrical properties of the polymer. Scanning electron microscopy shows PPy coatings to comprise individual polymer spheres, approximately 100 to 150 nm in diameter. The average size of the polymer spheres of PAn was observed to be approximately 50 to 100 nm in diameter. These spheres fuse together in a continuous sheet to coat the fibers in their entirety. The reduction of silver ions to silver metal nanoparticles onto the redox active polymer surface has also been successful and thus imparts anti-microbial properties to the hybrid materials. This gives rise to further applications requiring the inhibition of microbial growth. The chemical and physical characterisation of such products has been undertaken through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electrical conductivity, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and the testing of their anti-microbial activity.     

Nanocomposites based on conducting polymers and carbon nanotubes: from fancy materials to functional applications

This review deals with recent progress on the development of nanocomposite materials formed by conducting organic polymers (COPs) and carbon nanotubes (CNs), both from a fundamental and applied point of view. The combination of the unique properties of CNs with COPs makes of these materials interesting multifunctional systems with great potential in many applications such as supercapacitors, sensors, photovoltaic cells and photodiodes, optical limiting devices, solar cells, high-resolution printable conductor, electromagnetic absorbers, and, last but not least, advanced transistors.     

Nanofiber preparation by whisker method using solvent-soluble conducting polymers

We prepared conducting polymer nanofibers by means of whisker formation in a solution by using solvent-soluble conducting polymers with alkyl or alkoxy side chains. A morphological characterization using an atomic force microscope indicated that they have one-dimensional nanofibrillar structures with typical heights of 3-10 nm. The conductivity of a single poly(3-hexylthiophene) (P3HT) nanofiber was measured using 300-nm-spacing Pt electrodes and the conductivity of 0.25 S/cm at 290 K was achieved by chemical doping using nitrosonium tetrafluoroborate. Considering the temperature dependence of the conductivity, the carrier transport in the single nanofiber was explained by a quasi-one-dimensional variable range-hopping model.     

Construction of electrochromic devices using thiophene based conducting polymers

Dual type polymer electrochromic devices (ECDs) based on poly(terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester) (PTATE), its copolymer with thiophene P(TATE-co-Th) and poly(3,4-ethylenedioxythiophene) (PEDOT) have been constructed. Spectroelectrochemistry, switching ability and stability of the devices were investigated by UV-Vis Spectrophotometer and Cyclic voltammetry. These devices exhibit low switching voltages (between 0.0 V and +1.6 V), short switching times with reasonable switching stability under atmospheric conditions.     

Graphene-doped polyaniline nanocomposites as electromagnetic wave absorbing materials

Graphene doped polyaniline (G-PANI) nanocomposites with good electromagnetic properties were synthesized using an in situ emulsion polymerization method. Polyaniline was synthesized in ammonium persulfate and hydrochloric acid solution system. Graphene was added during the polymerization of aniline. Scanning electron microscopy and transmission electron microscopy analyses were performed to characterize the morphology of the nanocomposites. X-ray photoelectron spectroscopy provided the evidence for the oxidation of graphene. Conductivity and electromagnetic performances of polyaniline were improved after graphene doping. The reflection loss of G-PANI showed that the best electromagnetic wave absorbing was achieved at the graphene/polyaniline mass ratio of 1.5?×?10^?3.     

牺牲硅胶骨架法制备盐酸黄连素印迹聚合物及其性能研究

以盐酸黄连素（berberine-C1）为模板分子,硅胶为牺牲载体,甲基丙烯酸（MAA）或4-乙烯基吡啶（4-VP）、二甲基丙烯酸乙二醇酯（EDMA）及偶氮二异丁腈（AIBN）分别为功能单体、交联剂及引发剂制备了黄连素印迹聚合物。用光学显微镜观察了聚合物形貌,红外光谱（IR）研究了印迹聚合物（Mip）对模板分子的再结合...     

Fabrication of a near-infrared sensor using a polyaniline conducting polymer thin film

Near infrared (NIR) photo-responsive polyaniline-based conducting thin films are developed for sensor application. Upon NIR illumination (2.43 W/cm²), the electrical conductance of the polyaniline thin films was enhanced 5.9% and the response time was 20 s. NIR sensing performance of polyaniline conducting polymer thin film is comparable with that of bolometric carbon nanotube (CNT) network devices with the merits of polymers over CNTs such as processability, productivity and economy.     

Crack detection in conducting materials using SQUID magnetometry

A highly sensitive multichannel SQUID gradiometer, optimized uniquely for spatial resolution, was used to map in two dimensions the magnetic field perturbations from circular holes and thin slots in conducting plates and strips, respectively. Holes as small as 0.75 mm radius in electrically conducting plates were measured directly using a single channel. Edge slots as short as 0.5 mm long in conducting strips were detected, using a multiple-channel measurement method which eliminated the effects from the edge of the strip and the current leads. Clear magnetic signatures from these simulated cracks were measured using low current densities. Numerical computations of the theoretical field distributions are presented which confirm the experimental results. Calculations indicate that much smaller defects should be detectable with an optimization of test parameters.     

Influence ofβ-cyclodextrin as an encapsule and as an inclusion complex dopant on conducting polyaniline

An investigation on the effect ofβ-cyclodextrin (CD) in both free and inclusion-complexed forms with a guest anionic metal complex, dioxalatodiaquochromate(III) (DDC), on the characteristics of conducting polyaniline (PANI) is carried out. Four materials, PANI (i.e. PANI-SO ₄ ²⁻ ), PANI-DDC, PANI-CD and PANI-CD + DDC were prepared byin situ chemical oxidative polymerization in aqueous H ₂SO₄ at pH 1 and subjected to electrical conductivity and spectral (IR and UV-vis bd measurements. DDC and CD when separately incorporated, reduce the conductivity of PANI by about half whilst their inclusion complex CD + DDC enhances it. Spectral characterization reveals that DDC as a dopant and CD as an encapsule exhibit their effects through adverse interaction with imine-amine N centres and benzenoid moiety of PANI. The inclusion complex CD + DDC, on the contrary, functions as a dopant by lying in between the chains and seems to promote the extended conformation of PANI chain and hence theπ -electron delocalization. Exposure of the material to methanol vapour causes a decrease in conductivity in PANI and PANI-CD while an increase in PANI-CD + DDC. This study makes explicit the distinct role of CD as an encapsule and CD + DDC inclusion complex as a dopant in altering the electrical property of PANI.     

Metal oxalate complexes as novel inorganic dopants: Studies on their effect on conducting polyaniline

Doped polyaniline materials with metal oxalate complexes of Cr, Fe, Mn, Co and Al were synthesized byin situ chemical oxidative polymerization of aniline using potassium perdisulphate as oxidant in aqueous sulphuric acid medium. These polymer materials were characterized by chemical analyses, spectral studies (UV-visible and IR), X-ray diffraction and thermal techniques and also by conductivity measurements by four-probe technique. The presence of complex anion in polyaniline material was confirmed by chemical and spectral analyses. The yield and conductivity of metal oxalate doped polyanilines were found to be high when compared to the simple sulphate ion doped polyaniline prepared under similar condition. UV-visible and IR spectral features not only confirmed the polyaniline doping by complex anions but also substantiated their facilitating effect on conductivity. The X-ray diffraction patterns indicated some crystalline nature in metal oxalate doped polyaniline and amorphous in polyaniline sulphate salt. The conductivity of the polymer samples strongly depended on the degree of crystallinity induced by complex counter anions as dopant. All the polymer materials, as evident from TGA curves, were observed to undergo three-step degradation of water loss, de-doping and decomposition of polymer. Further, the thermal stability of polyaniline was found to improve on doping with metal oxalate complex.