PAN/PANI/rGO/Au复合纤维的制备及其催化、原位SERS监测性能研究

负载型贵金属纳米催化剂是提高贵金属催化剂利用率,降低经济成本的一种有效途径,也是一种新型的有潜力的表面增强拉曼光谱(SERS)的基底材料。本文首先利用静电纺丝技术构建了还原的氧化石墨烯(rGO)增强的聚丙烯腈/聚苯胺复合纤维(PAN/PANI/rGO),然后采用原位还原的方法在其表面生长金纳米颗粒得到了PAN/PANI/rGO/Au复合纤维,通过SEM, FTIR, XRD, XPS, Raman和UV-Vis光谱等手段对复合纤维进行了结构和形貌表征,最后以NaBH₄还原四硝基苯酚(4-NP)为模型,研究了复合纤维的催化性能和原位SERS检测该催化还原反应的过程,并将其与同种方法制备的PAN/PANI/GO/Au和PAN/PANI/Au复合纤维进行比较。结果表明,rGO增强的PAN/PANI/rGO/Au复合纤维具有优于PAN/PANI/GO/Au和PAN/PANI/Au复合纤维的催化活性、原位增强拉曼检测的能力和循环性能。     

Friction and wear behaviours of in situ reduced graphene oxide reinforced zirconia ceramic

The tribological behaviour of zirconia composites reinforced by in situ reduced graphene oxide (IrGO) was investigated by a rotating ball-on-plate configuration at room temperature, and was followed by a comparison with composites reinforced by pre-reduced graphene oxide(rGO). The results indicate that both the friction and wear resistance of ceramics increase with the incorporation of graphene oxide (GO). IrGO is better for enhancing the tribological performance of zirconia than rGO. The wear rate decreases by up to one order of magnitude (from 2.33 × 10⁻⁵ mm³·N⁻¹·m⁻¹ to 4.66 × 10⁻⁶ mm³·N⁻¹·m⁻¹) with 0.5 wt% GO. A protective tribofilm containing reduced graphene oxide forms at wear surfaces of ceramics, and the protruding-out of rGO is more pronounced. The main wear mechanism changes from severe delamination to plastic deformation and micro-cracking with increasing GO content. The analysis of wear tracks for ceramics with GO additives by Raman mapping reveals a decrease in the tetragonal-monoclinic phase transformation after sliding wear, which is regarded as the intrinsic reason for the improved wear resistance.     

Water dispersible conducting nanocomposites of poly(N-vinylcarbazole), polypyrrole and polyaniline with nanodimensional manganese (IV) oxide

Water dispersible composites of poly(N-vinylcarbazole) (PNVC), polypyrrole (PPY) and polyaniline (PANI) with colloidal MnO₂ were prepared. The incorporation of the polymers in the composites was endorsed by FTIR studies. SEM analyses revealed distinct morphological features of the composites. TEM analyses confirmed particle sizes to be in the nanometer range. DC conductivities of the PNVC–MnO₂ composites were 10⁷ to 10¹⁰ fold improved relative to the base polymer while those for PPY–MnO₂ or PANI–MnO₂ composites increased with the increasing polymer loading and dopant amount.     

A hybrid polymer of polyaniline and phthalimide dyes

A novel polyaniline derivative containing an emissive chromophore in its backbone was prepared by a palladium-catalyzed aryl amination. The incorporation of a 3,6-diamino phthalimide dye imparts a red color to the leucoemeraldine base analogues while reducing the overall electron density in the chain. The incorporated dye acts as a colorimetric tag indicative of the oxidation state of the polyaniline analogue. The three different oxidation states of the polymers were unambiguously characterized by comparison with an oligomeric model compound using IR and UV–vis spectroscopy. The emeraldine analogue of the polymer shows a measured conductivity of 10⁻⁵ S cm⁻¹ and unlike polyaniline, this material exhibits yellow fluorescence in solution. A cyclic tetramer was also isolated from the reaction mixture and 2D-WAXS measurements on an extruded fiber reveal that it forms a hexagonal columnar packing.     

Sulfonated polyaniline–titanium dioxide nanocomposites synthesized by one-pot UV-curable polymerization method

Sulfonated polyaniline–titanium dioxide (SPAni–TiO₂) hybrid composites have been synthesized by using a new strategy in one-pot system of UV-cured polymerization method. Aqueous solution of aniline and orthoanilinic acid comonomers, a free-radical oxidant and titania precursor were irradiated by UV rays. Hydrolysis and reprecipitation of the titania precursor in aqueous aniline and orthoanilic acid lead to the formation of titanium dioxide particles which in turn catalyze oxidation of comonomers to sulfonated polyaniline. The resultant SPAni–TiO₂ composites were characterized by using different spectroscopy analyses like X-ray diffraction, UV–visible (UV–vis) and infrared spectroscopy. The UV–vis absorption bands revealed that SPAni–TiO₂ nanocomposites are optically active and the blue-shifted peaks due to the presence of titania within the SPAni matrix. 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 SPAni–TiO₂ composites have a good thermal stability than the pristine SPAni.     

Preparation of TiO2/PANI composites in the presence of surfactants and investigation of electrical properties

“In situ” polymerization was carried out in the presence of titanium dioxide (TiO₂) to synthesize TiO₂/polyaniline (TiO₂/PANI) composite in an aqueous medium containing anionic (sodium dodecylbenzenesulfonate), DBSNa, cationic (tetradecyltrimethylammonium bromide), TTAB, and nonionic surfactants (poly(ethylene oxide) (20) sorbitan monolaurate), Tween 20). The composites were characterized by FTIR, UV–vis spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Gouy balance measurements. The FTIR and UV–vis spectra reveal that the interaction between TiO₂/PANI composite and surfactants. The anionic and cationic surfactants incorporated with TiO₂/PANI composite structure. The stability of the composites in terms of direct-current electrical conductivity retention was studied in isothermal conditions. Electrical conductivity measurements indicate that the conductivity of TiO₂/PANI synthesized in the presence of the cationic surfactant has the highest conductivity value. All composites showed negative mass magnetic susceptibility values.     

Stable polyaniline dispersions prepared in nonaqueous medium: synthesis and characterization

Peroxodisulfate-induced polymerization of aniline at 10°C in acidic (HCl) nonaqueous medium using dimethyl sulfoxide (DMSO) as the solvent, readily produced polyaniline (PANI) in a stable dispersion form. The stability of the dispersion of PANI in the nonaqueous (DMSO) medium is much enhanced when the same is synthesized in the presence of a support polymer, poly(vinyl alcohol) (PVA) dissolved in the solvent. Results of studies on HCl-doped PANI prepared in DMSO medium by UV–VIS and FTIR spectroscopy support that the doped PANI so obtained is structurally similar to that of doped PANI prepared likewise in acidic aqueous medium. PANI and PANI–PVA composite as prepared in DMSO medium and the relevant isolated dry products were further characterized thermally, employing differential scanning calorimetry (DSC) and thermogravimetry (TG) and morphologically, employing transmission electron microscopy (TEM). HCl-doped PANI prepared separately in DMSO and aqueous media shows electrical conductivity values of 1.07 and 12.0 S cm⁻¹, respectively, the polymer prepared in nonaqueous medium (DMSO) being measurably poorer in electrical conductivity,     

Chemical in situ polymerization of polypyrrole on bacterial cellulose nanofibers

Conducting porous nanofibrous composite membranes of bacterial cellulose (BC) and polypyrrole (PPy) were prepared through in situ oxidative chemical polymerization of pyrrole (Py) on the surface of synthetized BC nanofibers by using FeCl₃ as oxidant agent. The influence of polymerization conditions on electrical conductivity, morphological and thermal stability of the BC/PPy composites was investigated. The amount of PPy deposited on the BC nanofibers increased with increasing the monomer concentration and reaction time while the electrical resistivity of the composites decreased due to the formation of a continuous layer that coated the nanofiber surface. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) of the composites revealed strong interaction between PPy and BC, as characterized by a blue-shift of C–N band of PPy towards pure PPy with increasing Py concentration. BC/PPy composites showed higher thermal stability than BC membrane due to the protective effect of the conducting polymer coating. Scanning electron microscopy (SEM) analysis of the composites revealed that PPy consisted of particles of mean size of 35 nm that form a continuous coating that fully encapsulates the BC nanofibers. The material properties obtained by the method described in this work for the BC/PPy composites open interesting possibilities for novel applications of electrically conducting bio-based composites, particularly those that may exploit the biocompatible nature of the BC/PPy membranous composite.     

Inverse emulsion polymerization: a new route for the synthesis of conducting polyaniline

An inverted emulsion process for the synthesis of the emeraldine salt of polyaniline (Pani) using a novel oxidizing agent namely benzoyl peroxide is described. The polymerization is carried out in a non-polar solvent in the presence of four different protonic acids as dopants and an emulsifier (sodium lauryl sulphate). The polymer salts were characterized spectroscopically by UV–VIS, FT-IR, FT-Raman and EPR. Thermal method namely TGA was employed to determine the stability of the salts and the activation energy for the polymer degradation. The conductivity of the salts were found to be of the order of 10⁻¹ S cm⁻¹.     

X-ray absorption spectroscopy of iron-doped conducting polymers

X-ray absorption spectroscopy (XAS) measurements were performed at the Fe K edge to determine the iron local structure in chemically prepared polyaniline (PANI) and polypyrrole (PPy) samples prepared with FeCl₃ as an oxidant. The samples were conditioned at different pHs by an acid–base treatment. In both as synthesized-doped polymers, the observed dispersed Fe atoms were predominantly coordinated to chlorine as Fe(III)Cl_x species, where x=6 for PANI and x=4 for PPy samples suggesting that the polymer–counteranion bonding is weaker than the iron–chelate one. For the PANI samples submitted to basic treatment, three different sets of Fe distances were found: five Fe–O at 2.00 Å, three Fe–Fe at approximately 2.80 Å and five Fe–Fe at 3.00 Å and the near-edge spectra showed the presence of octahedrally coordinated Fe⁺³. These results strongly suggest the presence of small oxide/hydroxide aggregates. Similar data were obtained for PPy treated with NH₄OH.     

Redox behaviour of polyaniline–palladium catalytic system in the presence of formic acid

Redox behaviour of polyaniline (PANI) films containing chemically incorporated palladium particles in the presence of formic acid was studied. Two types of PANI–Pd hybrids were prepared: PANI-PdHA and PANI-PdLA, depending on the acidity of the PdCl₂ solution used for the introduction of palladium into the polymer matrix. UV–vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to examine the nature of processes involved upon the decomposition of formic acid on polyaniline–palladium hybrids. In particular, UV–vis changes of both kinds of films were followed in situ (in 1 M aqueous HCOOH solution) as a function of time. Rather unexpectedly, the redox properties of polyaniline films are found to be significantly altered in the presence of palladium particles. Particles of Pd⁰ promote the reduction of PANI from the most oxidized and semi-oxidized states to the most reduced one with simultaneous decomposition of formic acid.     

聚苯胺纳米线复合材料的制备与储能性分析

针对软、硬模板法制备纳米线的缺陷,提出一种步骤简单、快速且低成本的方法来获得直径均匀的PANI纳米线复合材料,并对所制备出的PANI纳米线复合材料进行表征和电化学性能研究。首先,采用阳极氧化剥离法,分别在硝酸体系、磷酸还原体系及硫酸体系中对表面光滑的石墨板进行电化学剥离处理。随后,在经过电化学剥离后的粗糙石墨表面上进行电聚合,从而得到PANI纳米线复合材料。表征分析发现,经电化学剥离处理的石墨纸表面分别生成具有大量活性点的石墨烯和氧化石墨烯,与PANI结合显著提高了PANI的导电性。其中硝酸体系制备的聚苯胺复合材料(PANI/GO)微观为纳米线组成的三维网状结构;磷酸还原体系制备的聚苯胺复合材料(PANI/GR1)微观是纳米线和纳米片层混合结构;硫酸体系制备的聚苯胺复合材料(PANI/GR2)的微观结构介于二者之间。以镁合金和上述三种PANI复合材料为电极,制备出简易的海水电池。使其在电流密度为3.75 m A·cm^-2下放电至0.9 V时止。三种电池的比能量分别为540、228和363 m Wh·g^-1,结果表明PANI/GO的储能性最优。...     

Morphology and electrical properties of hybrid and sulphonated oxalic acid-doped polyaniline

Polyaniline–polyethylene glycol2000 (PAni–PEG2000) hybrid and sulphonated polyaniline (SPAni) were prepared using oxalic acid as dopant and potassium permanganate as oxidant. The properties of these two conductive polymers were studied in comparison with pure polyaniline (PAni) prepared using the same conditions. The investigated polymers were characterized using FTIR, UV–vis, TGA, TEM, SEM, XRD and their electrical conductivities were also investigated. The morphology of pure polymer was found to be flat ribbon-like form, while presence of polyethylene glycol led to the formation of separate nanospheres. The three polymer samples have different degrees of crystallinity, the highest degree is for SPAni. Unexpectedly, electrical conductivity is in the order SPAni > PAni–PEG2000 > PAni, aging of PAni increases gradually the conductivity of the polymer from 0.0056 to 0.023 S cm^?1 and the increase of temperature gradually decreases the conductivity.     

Induced doping by sodium ion in poly(m-aminophenol) through the functional groups

Poly(m-aminophenol) (PmAP) was synthesized by the oxidative polymerization of m-aminophenol in sodium hydroxide medium using ammonium persulfate oxidant at room temperature. The synthesized polymer showed very good solution processability as it was well soluble in aqueous sodium hydroxide, dimethylsulfoxide (DMSO), dymethylformamide (DMF), etc. A free-standing film was cast from thermal evaporation of DMSO solution of the synthesized PmAP. The film was then doped with aqueous sodium hydroxide and methanol mixture by solution doping technique at room temperature. The doping conditions were standardized in terms of the DC-conductivity of the doped film. The doped PmAP was characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Electron dispersion spectroscopy, X-ray diffraction spectroscopy, elemental analysis by atomic absorption spectroscopy, thermogravimetric analysis and DC-electrical conductivity. The DC-electrical conductivity of PmAP film was increased to 2.34 × 10^?5 S/cm from <10^?12 S/cm due to sodium ion doping. From all the above characterizations it was confirmed that the sodium ions were not the reason for the conduction. The incorporated sodium cation in the polymer through free –OH groups of the polymer chain was induced the electron cloud of the polymer and so the polymer became conducting.     

Charge transport mechanism and the effect of poling on the current-voltage characteristics of conducting polyaniline–BaTiO3 composites

Conducting polyaniline–barium titinate (PANI–BaTiO₃) composites have been synthesized by `in situ' deposition technique by placing the fine grade powder of BaTiO₃ (prepared by conventional sol–gel technique) in the polymerization reaction mixture of aniline — finally yielding the Polyaniline–BaTiO₃ composites. The charge transport process in these composites have been studied by sandwiching the pellets of these composites between the silver and platinum electrodes. It presumably suggests presence of a nonlinear space charge controlled charge transport process. Also, a large hysteresis in the I–V characteristics of these composites has been observed which also supports the space charge controlled conduction. The samples were poled by applying a constant voltage for a fixed time and the I–V characteristics were traced before and after poling. Some striking differences have been observed in the I–V characteristics before and after poling. These have been explained on the basis of creation of an internal electric field due to poling which in turn opposes the externally applied electric field.     

Enhanced field emission from polyaniline nano-porous thin films on PET substrate

Conducting polyaniline (PANI) nano-porous film synthesized on PET substrate by vapor deposition technique has shown excellent field emission behaviour and the emission was further enhanced by conditioning with vacuum electric discharge. Detailed study on the field emission for PANI films synthesized with different oxidant concentration was performed. Measurement was also carried out for different anode-sample separation. Turn-on field as low as 0.5 V/μm and emission current density as high as 20.96 mA/cm² was observed. The field enhancement factors were found to be in the range of 1192–3782. The films were characterized with X-ray diffraction, UV–vis spectroscopy, Fourier transformed infrared spectroscopy, scanning electron microscopy and also atomic force microscopy. The synthesized PANI films may be a promising material for field emission devices and also for plastic display industry.     

Electrochemical synthesis of self-doped polyaniline in fluorosulfonic acid/acetonitrile solution

Electrochemical formation of self-doped sulfonated polyaniline (SPAN) was carried out in acetonitrile-containing anhydrous fluorosulfonic acid (FSO₃H). Fluorosulfonic acid was used as both sulfonation reagent for aniline and also as supporting electrolyte. The degree of sulfonation of the polymer was controlled by varying FSO₃H and aniline concentrations while the film is being deposited. Different dry conductivity values for the polymer (1.24–14.6 S/cm) were measured depending on the degree of sulfonation of polyaniline. Polychromic behavior of SPAN (transparent yellow–green–dark blue) was observed when the cyclic voltammograms were taken between −0.30 and +1.90 V (vs. Ag/AgCl, saturated) during the growth of polyaniline film. The polymers having different degrees of sulfonation were found to be soluble in basic aqueous solution, dimethyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP). SPAN was characterized by elemental analysis, FT-IR spectroscopy, UV–visible spectroscopy and cyclic voltammetry.     

烧结钕铁硼表面复合电沉积氧化石墨烯镀锌层

目的烧结钕铁硼(NbFeB)是一种应用范围非常广泛的多孔磁性材料,由于多孔结构易发生腐蚀,需在其表面制备相应的镀层进行防护。方法利用电沉积法将提前制备的氧化石墨烯(GO)与镀锌溶液混合,在NdFeB基体表面电沉积制备出锌镀层与氧化石墨烯复合镀锌层。结果镀锌液中,氧化石墨烯(GO)的浓度、阴极电流密度以及搅拌速度,对复合镀锌层的表面微观形貌具有一定的影响,同时一定浓度的氧化石墨烯(GO)可以改变镀层的生长取向,Zn/rGO的优先生长晶面由(100)变成(002)。膜层的微观形貌从纯锌紧密堆积在一起的凸起晶粒变成了Zn/rGO的纳米片状形貌。交流阻抗和动电位极化曲线结果表明,镀Zn层和Zn/rGO复合镀锌层经过3.5%Na Cl溶液中浸泡后,Zn/rGO纳米复合镀层的耐腐蚀性能明显增加。结论相比于单一的镀锌层,Zn/GO复合镀锌层的耐腐蚀性明显增加。     

Conducting polyaniline based paints on low carbon steel for corrosion protection

Conducting polyaniline powder was synthesized chemically and paints containing conducting polyaniline powder were applied on low carbon steel samples. The conducting polyaniline powder was characterized by UV-Visible absorption spectroscopy and the morphology of paint coating on low carbon steel was studied by scanning electron microscopy. The corrosion protection performance of the coating was evaluated by using potentiodynamic polarization techniques and electrochemical impedance spectroscopy. It has been found that the 2 wt % polyaniline-hydrochloric acid based paint coating offers maximum corrosion protection to low carbon steel in chloride medium.     

Corrosion protection of aluminum alloy by epoxy coatings containing polyaniline modified graphene additives

In the study, polyaniline/reduced‐graphene oxide (PANI‐RGO) composites, fabricated by loading 2, 5, and 8wt% graphene oxide, was prepared by in‐situ emulsion polymerization and reduction. They are characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. Epoxy coatings adding PANI and PANI‐RGO composites were coated on the surface of AA5083 Al alloy. The anticorrosion performance of the coatings is measured by electrochemical impedance spectroscopy and potentiodynamic polarization curve in 3.5wt% NaCl solution. The results demonstrate that the epoxy/PANI‐RGO coating exhibits a better protection against AA5083 alloy corrosion compared with the epoxy/PANI coating. Enhancement of the passivation performance of PANI was obtained by the addition of RGO into epoxy/PANI coating system.