PANI/Ce(OH)_3-Pr_2O_3·3H_2O/NanoG复合材料的热稳定性及导电性

采用一种制备纳米复合材料的新方法——反胶束模板-原位聚合一步法成功地制备了PANI/Ce(OH)3-Pr2O3.3H2O/NanoG复合材料,并系统研究了其热稳定性及导电性能。测试结果表明,该复合材料的热稳定性较纯聚苯胺(PANI)有了明显的提高;石墨纳米薄片(NanoG)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/Ce(OH)3-Pr2O3.3H2O/NanoG复合材料的渗滤阀值低于1.0%。     

石墨及其改性产物研究进展

天然石墨是具有片层结构的含碳无机材料,层间由范德华力连接,可用物理或化学方法将其它分子、原子、离子甚至原子团插入其层间,生成石墨层间化合物(GIC);GIC经高温膨胀可得到体积为其几百倍的膨胀石墨(EG);在超声粉碎时,膨胀石墨上的石墨微片剥离,得到纳米石墨微片(NanoG)。近年来,富勒烯(Fullerence)、碳纳米管(CNT)、石墨烯(Graphene)的先后开发,为石墨家族注入新的活力,并为其应用开辟了新的空间。系统论述了天然石墨及其改性产物如EG、NanoG、Graphene、CNT、Fullerence的结构、制备方法、性质及用途。     

Nd3+取代铁氧体与纳米石墨微片复合物的合成及性能研究

采用共沉淀法将Nd3+取代的Fe3O4与纳米石墨微片(NanoG)复合得到复合物NdxFe3-xO4/NanoG.通过SEM、LPSA、EDS、XRD和FTIR等对该复合物的结构进行了表征.当x=0.06时,Nd0.06Fe2.94O4具有尖晶石结构,其粒径主要分布在70～80 nm间.VSM的测试表明:Nd0.06Fe2.94O4为软磁性铁氧体,具有较高的饱和磁化强度(Ms =43.74 emu/g),与NanoG复合后,饱和磁化强度下降到39.45 emu/g.对电磁参数的测试表明:当x=0.06,Nd0.06Fe2.94O4与NanoG的质量比为4∶1时,在X波段(8.2～12.4 GHz),Nd0.06Fe2.94O4/NanoG在11.90 GHz处的最小损耗为Rmin=-17.13 dB,具有较好的微波吸收性能.     

石墨纳米片对铜电子浆料导电性的影响

为改善铜浆导电性,以表面改性的金属铜粉为主要导电相,通过添加少量导电性优异的石墨纳米片作为导电增强相制备复合电子浆料,并采用四探针测试仪、扫描电子显微镜(SEM)等分析测试方法研究了石墨纳米片的参数、添加量对铜电子浆料导电性能的影响.结果表明:选用厚度为3~5 nm,片径为5μm的石墨纳米片作为导电增强相,制得石墨纳米片—铜电子浆料,在460℃烧结后导电膜层的电阻率较小;石墨纳米片与铜粉质量比为2∶98时,测得浆料电阻率为17.14 mΩ·cm,相比纯铜浆料电阻率34.43 mΩ·cm降低了50.22%.分析电子浆料导电机理并建立导电相连接几何模型,在导电膜层中,部分折断的石墨纳米片会填充到铜颗粒之间的空隙中,较长石墨纳米片则会形成"搭桥"现象,增加导电相之间的连接,形成较紧密的微观组织和良好的导电网络,从而改善复合浆料的导电性.     

石墨在固相剪切碾磨力场下的片层剥离及与PVC的纳米复合

采用固相剪切复合技术成功制备石墨-聚氯乙烯(PVC)复合粉体, 实现了石墨的片层剥离和在PVC基体中的纳米分散及对PVC的抗静电改性。通过XRD、 SEM、 TEM等表征了石墨-PVC/PVC复合材料的结构, 研究了其抗静电性能。结果表明, 石墨的片层厚度约20 nm, 径厚比超过10。固相剪切碾磨技术制备的石墨-PVC/PVC复合材料的导电性能有较大提高。在石墨质量分数为2%时, 表面电阻率为4.6×10⁷ Ω·cm, 已达到了抗静电材料的要求, 实现了低填充。在石墨质量分数为10%时, 表面电阻率达到最低的4.1×10⁴ Ω·cm。     

PANI-HCl/PAN电磁屏蔽纳米纤维膜的制备与表征

用化学方法合成盐酸掺杂的导电聚苯胺,然后以静电纺丝技术制备PANI-HCl/PAN纳米柔性电磁屏蔽材料。利用红外光谱和扫描电镜分别对纳米纤维结构和形貌进行表征分析,并用电子万能试验机和矢量网络分析仪分别对导电聚苯胺薄膜的力学性能及屏蔽特性进行了测试和分析。结果表明,随着PANI-HCl含量的增加,纺丝溶液的电导率增加,纳米纤维直径减少,力学性能降低;PANI-HCl/PAN纳米薄膜的电磁屏蔽性能随着薄膜厚度的增加,电磁屏蔽性能提高,当薄膜厚度为91.04μm时,薄膜的电磁屏蔽效能达到20.38dB;同时,纳米纤维膜在低频段均表现良好的电磁屏蔽效果,在1～9MHz频率范围内,当聚苯胺的含量达到13%时,屏蔽率达到90%以上。     

NanoG/BMI纳米减摩复合材料的制备及其性能

利用扫描电子显微镜(SEM)和X射线衍射(XRD)手段研究纳米石墨薄片(NanoG)制备条件对层间结构与润滑性能影响,首次以NanoG为润滑剂制备的NanoG/BMI纳米减摩复合材料,研究其减摩性能和耐热性能及力学性能.研究表明:NanoG主要是由具有石墨的标准002特征峰的多层碳-碳六方平面结构的“亚结构单元“构成,其润滑性能主要是由于这些多层“亚结构单元“之间易相对滑动的结果;3%～5%NanoG或NanoG MoS2制备的NanoG/BMI或NanoG MoS2/BMI纳米减摩复合材料减摩性能优于20%石墨粉制备的传统减摩复合材料或与其相当,而前者的力学性能远优于后者,且均具有较好的耐热性能.     

聚乙烯醇/纳米石墨片复合材料的制备及导电性能EI北大核心CSCD

首先使用高压均质法在水溶液中制备纳米石墨片(GNS),然后用溶液法制备了不同浓度的聚乙烯醇/纳米石墨片(PVA/GNS)复合膜。使用扫描电镜、原子力显微镜对GNS的形貌进行了表征。结果表明,高压均质法可以在水溶液中有效地剥离石墨片,剥离得到的GNS的厚度范围在几纳米至几十纳米。通过与聚乙烯醇/石墨粉(PVA/Graphite)混合液的对比,发现GNS在PVA溶液中有更好的分散性。本文考察了室温下PVA/GNS复合膜在不同GNS添加量情况下的导电性。结果表明PVA/GNS复合膜具有比石墨粉更低的渗流阈值,其渗流阈值低至3.36%(体积分数),并用渗流理论验证并解释了复合物的导电特性。     

镀镍纳米石墨微片的制备及其表征

采用化学镀制备镀镍纳米石墨微片(Ni-nanoG), 对其进行制备工艺研究及结构表征, 旨在得到一种新型导电导磁填料。讨论了硫酸镍浓度、 次亚磷酸钠浓度、 温度、 pH值对石墨微片镀层的影响, 得出镀镍的最佳工艺。采用SEM、 XRD、 EDS对其结构进行了表征, 并用振动样品磁强计(VSM)测试了其磁性能。结果表明: 纳米石墨微片(nanoG)表面镀上了一层紧凑的金属镍。镍均匀分布在nanoG的表面和边界面上, 将nanoG包覆得较严实。 Ni-nanoG厚度约为150 nm。nanoG上镍的含量较高, 其质量分数大约为34.08%。Ni-nanoG的饱和磁化强度为71.2 A·m2·kg-1, 可以作为吸波隐身材料的新型功能型填料。      

聚乙烯醇/纳米石墨片复合材料的制备及导电性能

首先使用高压均质法在水溶液中制备纳米石墨片(GNS),然后用溶液法制备了不同浓度的聚乙烯醇/纳米石墨片(PVA/GNS)复合膜。使用扫描电镜、原子力显微镜对GNS的形貌进行了表征。结果表明,高压均质法可以在水溶液中有效地剥离石墨片,剥离得到的GNS的厚度范围在几纳米至几十纳米。通过与聚乙烯醇/石墨粉(PVA/Graphite)混合液的对比,发现GNS在PVA溶液中有更好的分散性。本文考察了室温下PVA/GNS复合膜在不同GNS添加量情况下的导电性。结果表明PVA/GNS复合膜具有比石墨粉更低的渗流阈值,其渗流阈值低至3.36%(体积分数),并用渗流理论验证并解释了复合物的导电特性。     

High conductivity and low percolation threshold in polyaniline/graphite nanosheets composites

An easy process for the synthesis of polyaniline/graphite nanosheets (PANI/NanoG) composites was developed. NanoG were prepared by treating the expanded graphite with sonication in aqueous alcohol solution. Scanning electron microscopy (SEM), X-ray diffraction techniques (XRD), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) were used to characterize the structures of NanoG and PANI/NanoG conducting composites. Electrical conductivity measurements indicated that the percolation threshold of PANI/NanoG composites at room temperature was as low as 0.32 vol.% and the conductivity of PANI/NanoG composites was 420 S/cm. The percolation theory, mean-field theory, and excluded volume theory were applied to interpret the conducting properties. Results showed that the low value of percolation threshold may be mainly attributed to nanoscale structure of NanoG forming conducting bridge in PANI matrix and there exists contact resistance in the percolation network formed within PANI/NanoG composites.     

Preparation and microwave absorbing property of silver-coated graphite nanosheet NanoG with Pyrrole

Microwave absorbing material PPy/Ag/NanoG was prepared by in situ polymerization of Pyrrole on the surface of silver-coated conductive graphite nanosheet (Ag/NanoG). The morphologies and nanostructures of PPy, Ag/NanoG and PPy/Ag/NanoG were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy analysis (EDS) and X-ray diffraction analysis (XRD) respectively. Results show that Ag/NanoG has layered structure with high aspect ratio (width-to-thickness) and most of Ag/NanoG nanoparticles are encapsulated by PPy. Measurement of electromagnetic parameters shows that the complex permittivity (ε* = ε′-jε″), complex permeability (μ* = μ′-jμ″), dielectric loss tanδ_e = ε″/ε′ and magnetic loss tanδ_m = μ″/μ′ of PPy/Ag/NanoG are superior to those of PPy. The reflection loss of PPy/Ag/NanoG is below −15 dB at the X band from 8.2 GHz to 12.4 GHz and the minimum loss value is − 18.21 dB at 9.86 GHz.     

Conducting polymer nanocomposites with extremely low percolation threshold

Abstract. This article gives a brief review of our work on conducting polyaniline nanocomposites which exhibit extremely low percolation threshold, ca. <003 vol.%. The nanocomposites are essentially blends of nanoparticles of HCI doped polyaniline (PANI) with conventional polymers. The nanoparticles (<20 nm) were prepared by sonicating a suspension of sterically stabilized conoidal PANI particles in solutions of conventional polymers. The sonication process breaks down the stable colloid particles into nanoparticles. The latter are unstable and they aggregate fractally to yield nanocomposites with extremely low percolation threshold.     

电磁搅拌法制备导电聚苯胺纳米线的电磁屏蔽性能研究

针对低频频段(<1.5GHz)的电磁屏蔽涂层,采用快速混合法制备出导电聚苯胺纳米线,使用透射电镜(TEM)对其形貌和尺度进行表征,研究了搅拌方式对聚苯胺/聚氨酯涂层的导电性能和电磁屏蔽性能的影响。研究表明,由于磁场的作用,采用电磁搅拌法可以缩短聚苯胺聚合反应时间,合成均一的导电聚苯胺纳米线,其渗滤阈值为33.3%,含量为33.3%的聚苯胺纳米线的聚苯胺/聚氨酯涂层的电磁屏蔽性能为32.2dB,优于含量为45%的机械搅拌法制备的聚苯胺粉体,这可能是由于线性结构的导电聚苯胺在基体中能够较容易形成三维导电网络结构所致。     

Free‐Standing,Multilayered Graphene/Polyaniline‐Glue/Graphene Nanostructures for Flexible,Solid‐State Electrochemical Capacitor Application

Graphene/polyaniline multilayered nanostructures (GPMNs) are prepared using a straightforward process through which graphite is physically exfoliated with quaternary polyaniline (PANI)‐glue. This is only accomplished by sonication of the graphite flakes in an organic solvent to form continuous films with PANI. During the sonication, the conductive PANI‐glue is spontaneously intercalated between the graphene sheet layers without deterioration of the sp² hybridized bonding structure. The resultant free‐standing, flexible films are composed of a network of overlapping graphene sheets and are shown to have a long‐range structure. The effects of different PANI content ratios and different interfacial energies (depending on the dispersion solvent) on the morphology and properties of the resulting GPMN are examined. It is found that GPMNs dispersed in water have a maximum specific capacitance of 390 F g⁻¹ in a three‐electrode configuration. Importantly, the unique structural design of GPMNs enables their use as electrode materials for the fabrication of flexible, solid‐state electrochemical capacitors, which show an enhanced performance compared to graphene‐only devices. They exhibit a high specific capacitance of 200 F g⁻¹, a cycling stability with capacitance retention of 82% after 5000 charge/discharge cycles, and, moreover, superior flexibility.     

Synthesis and characterization of polyaniline-camphorsulphonic acid nanotube film

Polyaniline (PANI) nanotubes were prepared in the bulk solution and as films using the aniline oxidation with ammonium peroxydisulfate in aqueous solutions of camphorsulfonic acid (CSA). The in situ PANI films produced during the oxidation of aniline in CSA and also in hydrochloric acid solutions were followed by monitoring the frequency changes of quartz crystal microbalance (QCM). The kinetics of the film formation were discussed. The scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) showed PANI nanotubes. In addition, nanorods and nanoflowers composed from nanofibers and nanoflakes are also present to some extent. The nanotubes were characterized using UV-Vis spectroscopy.     

Polyaniline/CuCl nanocomposites prepared by UV rays irradiation

In present paper, polynailine (PANI)/CuCl nanocomposites were prepared by UV rays irradiation method. In this method, photons in the UV rays and Cu²⁺ ions replaced conventional oxidant such as ammonium persulfate (APS) to promote polymerization of aniline monomer. The PANI/CuCl nanocomposites were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), and electron diffraction (ED). The results indicated that aniline could polymerize to PANI by UV rays irradiation. Meanwhile, the results of HRTEM and ED confirmed that the CuCl dispersed into PANI was single crystal with cubic crystal structure. A potential formation mechanism of PANI/CuCl nanocomposites was investigated and suggested.     

Synthesis of polyaniline nanofibrous networks with the aid of an amphiphilic ionic liquid

In this work, polyaniline (PANI) nanofibrous networks were prepared using ionic liquid (IL), 1-hexadecyl-3-methylimidazolium chloride (C16MIMCl), as a template through oxidative polymerization of aniline with ammonium persulfate. The resulting PANI was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, and FTIR. It was indicated that the as-prepared PANI was in the emeraldine form and its morphology strongly depended on the molar ratio of aniline/C16MIMCI. A possible mechanism for the formation of PANI nanofibrous networks was that the ordered micro-domains of the IL acted as template to direct the growth of the nanostructures.     

Conducting polyaniline nanoparticles and their dispersion for waterborne corrosion protection coatings

A novel approach for preparing waterborne corrosion protection polyaniline (PANI)-containing coatings was developed. First, conducting polyaniline/partially phosphorylated poly(vinyl alcohol) (PANI/P-PVA) spherical nanoparticles with significant dispersibility in aqueous media were prepared by the chemical oxidative dispersion polymerization in presence of partially phosphorylated poly(vinyl alcohol) (P-PVA). The PANI/P-PVA-containing coatings with different PANI/P-PVA contents were then prepared, employing waterborne epoxy resin as the matrix. The corrosion protection property of PANI/P-PVA-containing coatings on mild steel was investigated by salt spray test and electrochemical impedance spectroscopy (EIS) technique in 3.0 wt % NaCl aqueous solution. The results indicated that the waterborne PANI/P-PVA-containing coatings (PANI/P-PVA content, 2.5 wt %) could offer high protection because the impedance values remained at higher than 1 × 10(7) Ω cm(2) after 30 days of salt spray tests. All the results were compared with these of the waterborne coatings containing PANI nanoparticles in the emeraldine salt form (PANI ES), and the protection mechanism was also proposed with the evidence of scanning electron microscope (SEM) and X-ray photoelectron spectrometry (XPS).     

Morphology and conductivity of polyaniline sub-micron fibers prepared by electrospinning

Sub-micron fibers of pure polyaniline (PANI) doped with sulfuric acid or hydrochloric acid were prepared by electrospinning PANI with suitable molecular weight dissolved in hot sulfuric acid. A modified electrospinning setup was employed with a coagulation bath as a collector, where dilute sulfuric acid was used as coagulation bath. The factors influencing the morphology and conductivity of the synthesized PANI fibers were investigated, including the concentration of dilute H₂SO₄ solution in the coagulation bath, the doped PANI concentration in H₂SO₄ solution, the type of doping acid and the voltage applied to the solution. The morphologies of doped PANI fibers were characterized by scanning electron microscope (SEM). The structure of the resulting fibers was analyzed by Fourier transform infrared spectroscopy and UV–vis spectrometer. The conductivity of PANI fibers were characterized by I–V characteristics. Homogeneous PANI fibers with a diameter of 370 nm and a high conductivity of 52.9 S/cm were prepared. The possible mechanisms of different morphology formation and conductivity of PANI fibers were also discussed.