Synthesis of PANI and Study of Morphology in the Process of Polymerization

The polyaniline micro/nanostructure was prepared by a self‐assembly process with molybdic acid as dopants in the presence of ammonium persulfate as the oxidant. It was found that the morphology of PANI micro/nanostructure was affected by the concentration of the dopant, that is, the morphology of PANI changed from nanofibers to co‐existence of nanofibers and microspheres as the molar ratio of molybdic acid to aniline varied from 0.01 to 1.5. Under the same condition it was also found that the conductivity value of PANI enhanced from 4.58×10^?3 S·cm^?1 to 3.8×10^?1 S·cm^?1. The structure of PANI was characterized by FTIR and XRD which confirmed the presence of the molybdic acid in the PANI. The electrochemical characteristics of the PANI nanofibers were investigated by means of cyclic voltammetry. The morphology of PANI in the process of polymerization was characterized by SEM. It was found that when the molar ratio of molybdic acid to aniline was 0.3, the morphology of PANI was co‐existence of nanofibers and microspheres and the formation of microspheres was ahead of the nanofibers.     

Conductive Nanocomposites Based on Cellulose Nanofibrils Coated with Polyaniline-DBSA Via In Situ Polymerization

Summary: Cellulose nanofibrils (CNF) were extracted by acid hydrolysis from cotton microfibrils and nanocomposites with polyaniline doped with dodecyl benzenesulphonic acid (PANI-DBSA) were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA to aniline and aniline to oxidant were varied in situ and the nanocomposites characterized by four probe DC electrical conductivity, ultraviolet-visible-near infrared (UV-Vis - NIR) and Fourier-transform infrared (FTIR) spectroscopies and X-ray diffraction (XRD). FTIR and UV-Vis/NIR characterization confirmed the polymerization of PANI onto CNF surfaces. Electrical conductivity of about 10⁻¹ S/cm was achieved for the composites; conductivity was mostly independent of DBSA/aniline (between 2 and 4) and aniline/oxidant (between 1 and 5) molar ratios. X-ray patterns of the samples showed crystalline peaks characteristic of cellulose I for CNF samples, and a mixture of both characteristic peaks of PANI and CNF for the nanocomposites. Field emission scanning electron microscopy (FESEM) characterization corroborated the abovementioned results showing that PANI coated the surface of the nanofibrils.     

Graphene oxide‐induced polymerization and crystallization to produce highly conductive polyaniline/graphene oxide composite

Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m^?1, compared with 20.3 S m^?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554     

Characterization and thermal degradation studies on polyaniline‐intercalated montmorillonite nanocomposites prepared by a solvent‐free mechanochemical route

Polyaniline (PANI)‐montmorillonite (MMT) nanocomposites were prepared by direct intercalation of aniline molecules into MMT galleries, followed by in situ polymerization within the nano‐interlamellar spaces under solvent‐free conditions. The basal spacing of aniline‐intercalated MMT increased gradually up to 1.5 nm with increasing amounts of aniline loaded. This result suggests that aniline molecules were adsorbed by MMT clay and that intercalated aniline likely located perpendicular to the silicate sheets. After polymerization, X‐ray diffraction and Fourier transform infrared analyses confirmed the successful synthesis of PANI chains between the MMT nano‐interlayers. The scanning electron microscopy images indicated that the surface morphologies of PANI–MMTs were strongly different depending on the PANI content. The electrical conductivities of PANI nanocomposite particles in pressed pellets ranged in the order of between 10^?3 and 10^?2 S/cm. UV–vis spectroscopy and doping level measurement were further used to discuss the conductivities of nanocomposites. The thermal stabilities of PANI–MMT nanocomposites were examined by using thermogravimetric‐differential thermal analysis and derivative thermogravimetric analysis, and both analyses consequently demonstrated the improved thermal stabilities of the PANI chains in the nanocomposites as compared to pure PANI. The thermal stabilities of resulting nanocomposites were strongly related to the PANI content, which increased as the PANI content decreased in the nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2705–2714, 2005     

超疏水导电聚苯胺的界面聚合

采用界面聚合和无模板法相结合的方法, 以具有疏水链的全氟癸二酸(PFSEA)为掺杂剂, 通过调节苯胺单体和FeCl₃氧化剂的浓度实现了聚苯胺三维微/纳米结构形貌和尺寸的可控制备. 扫描电子显微镜测量结果显示, 聚苯胺是由一维纳米纤维自组装形成的三维微球结构; 红外吸收光谱和紫外-可见吸收光谱结果表明, 聚苯胺微球为掺杂态. 室温下, 该微/纳米结构聚苯胺微球的电导率为 9.6×10^-3 S/cm, 表面水接触角为161.4°, 表现出半导体特性和超疏水性.     

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.     

Electrical conductivity of poly(ethylene terephthalate)/expanded graphite nanocomposites prepared by in situ polymerization

Nanocomposites based on poly(ethylene terephthalate) (PET) and expanded graphite (EG) have been prepared by in situ polymerization. Morphology of the nanocomposites has been examined by electronic microscopy. The relationship between the preparation method, morphology, and electrical conductivity was studied. Electronic microscopy images reveal that the nanocomposites exhibit well dispersed graphene platelets. The incorporation of EG to the PET results in a sharp insulator‐to‐conductor transition with a percolation threshold (?_c) as low as 0.05 wt %. An electrical conductivity of 10^?3 S/cm was achieved for 0.4 wt % of EG. The low percolation threshold and relatively high electrical conductivity are attributed to the high aspect ratio, large surface area, and uniform dispersion of the EG sheets in PET matrix. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Structural and electrochemical characterization of polyaniline/LiCoO2 nanocomposites prepared via a Pickering emulsion

Polyaniline (PANI)/LiCoO₂ nanocomposite materials are successfully ready through a solid-stabilized emulsion (Pickering emulsion) route. The properties of nanocomposite materials have been put to the test because of their possible relevance to electrodes of lithium batteries. Such nanocomposite materials appear thanks to the polymerization of aniline in Pickering emulsion stabilized with LiCoO₂ particles. PANI has been produced through oxidative polymerization of aniline and ammonium persulfate in HCl solution. The nanocomposite materials of PANI/LiCoO₂ could be formed with low amounts of PANI. The morphology of PANI/LiCoO₂ nanocomposite materials shows nanofibers and round-shape-like morphology. It was found that the morphology of the resulting nanocomposites depended on the amount of LiCoO₂ used in the reaction system. Ammonium persulfate caused the loss of lithium from LiCoO₂ when it was used at high concentration in the polymerization recipe. Highly resolved splitting of 006/102 and 108/110 peaks in the XRD pattern provide evidence to well-ordered layered structure of the PANI/LiCoO₂ nanocomposite materials with high LiCoO₂ content. The ratios of the intensities of 003 and 104 peaks were found to be higher than 1.2 indicating no pronounced mixing of the lithium and cobalt cations. The electrochemical reactivity of PANI/LiCoO₂ nanocomposites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO₂ nanocomposite materials exhibited better electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO₂ cathode. The best advancement has been observed for the PANI/LiCoO₂ nanocomposite 5 wt.% of aniline.     

Formation of polyaniline nanofibers: a morphological study

Polyaniline (PANI) powders were prepared by solution precipitation, rapid mixing polymerization, and interfacial polymerization to find the key factors that influence the formation and growth of PANI nanofibers. In chemical oxidative polymerization of aniline, the morphology of the product is mainly determined by aniline concentration. In the case of lower aniline concentration, PANI nanofibers were formed and can be preserved and collected as final product, while in the case of higher aniline concentration, larger sized PANI particles or agglomerates were obtained owing to the growth of the nanofibers. Without participation of the oxidizing step, solid PANI samples with compact structures and dissimilar morphologies were achieved by random accumulation of PANI molecules.     

Enhancing dielectric and mechanical behaviors of hybrid polymer nanocomposites based on polystyrene,polyaniline and carbon nanotubes coated with polyaniline

The dielectric and mechanical properties of hybrid polymer nanocomposites of polystyrene/polyaniline/carbon nanotubes coated with polyaniline(PCNTs) have been investigated using impedance analyzer and extensometer. The blends of PS/PANI formed the heterogeneous phase separated morphology in which PCNTs are dispersed uniformly. The incorporation of a small amount of PCNTs into the blend of PS/PANI has remarkably increased the dielectric properties. Similarly, the AC conductivity of PS/PANI is also increased five orders of magnitude from 1.6 × 10~(-10) to 2.0 × 10~(-5) S·cm~(-1) in the hybrid nanocomposites. Such behavior of hybrid nanocomposites is owing to the interfacial polarization occurring due to the presence of multicomponent domains with varying conductivity character of the phases from insulative PS to poor conductor PANI to highly conductive CNTs. Meanwhile, the tensile modulus and tensile strength are also enhanced significantly up to 55% and 160%, respectively, without much loss of ductility for three phase hybrid nanocomposites as compared to the neat PS. Thereby, the hybrid nanocomposites of PS/PANI/_P CNTs become stiffer, stronger and tougher as compared to the neat systems.     

氯化铁氧化掺杂的聚苯胺纳米纤维团簇

没有外加质子酸的条件下,以氯化铁为氧化剂和掺杂剂,在界面体系中由苯胺(An)采用“无模板”的方法成功地制备了电导率为10-2～10-1S/cm的聚苯胺纳米纤维(d=20～30nm).实验证明FeCl3同时起到氧化剂和掺杂剂的双重作用,从而进一步简化了导电聚苯胺纳米纤维的合成条件.与使用过硫酸铵为氧化剂的传统聚合方法相比,FeCl3较小的氧化/还原电位使产物具有较小的直径和较高的结晶性.同时发现聚苯胺的形貌和电导率均与[FeCl3]/[An]的比例有关.FTIR,UV-Vis,XRD结构表征证实所得的聚苯胺纳米纤维为掺杂态.     

Simple Preparation of Sulfate Anion‐Doped Polyaniline‐Clay Nanocomposites by an Environmentally Friendly Mechanochemical Synthesis Route

Summary: Conducting polyaniline (PANI) and montmorillonite (MMT) nanocomposites were prepared from aniline sulfate and MMT by a mechanochemical synthesis route. X‐Ray diffraction analysis confirmed that, by controlling the aniline sulfate content, mechanochemical synthesis led to two types of different formations. After polymerization, the mechanochemical route synthesized much more PANI between the clay layers compared to a solution method. The electrical conductivities of the synthesized PANI‐MMT nanocomposites in pressed pellets ranged in the order of between 10⁻⁴ and 10⁻³ S · cm⁻¹.

X‐ray powder diffraction patterns of the intercalation products prepared by grinding montmorillonite with various amounts of Ani‐SO₄ in a mortar.     

Exploration on the microwave‐assisted synthesis and formation mechanism of polyaniline nanostructures synthesized in different hydrochloric acid concentrations

Under microwave‐assisted synthesis, polyaniline (PANI) products with multiple nanostructures were synthesized by the oxidative polymerization of aniline and ammonium peroxodisulfate in the different concentrations of hydrochloric acid solutions. The structural analysis of PANI using FTIR, UV, and XPS indicated that phenazine‐like oligomers were produced in acid‐free and low acidic systems. Moreover, long linear PANI chains were obtained in the presence of highly acidic solutions. The morphology of PANI observed by SEM and TEM showed that nanoscale structures, including stacked sheets, nanotubes, branched nanofibers, and uniform nanofibers, occurred respectively in acid‐free solution, low acidity, medium and high acidity systems, effectively regulating by acidity. The formation mechanism of PANI nanostructures was explored here. The sheets were formed by the oligomers containing flat phenazine rings that can be stacked together with strong π–π interactions. Furthermore, nanotubes were fabricated by the self‐curling of thin sheets consisted of phenazine‐like oligomers with numerous linear units in the chains. The nanofibers are supposed to form by the linear PANI chains and the secondary growth during aniline polymerization caused the branch formation on the nanofibers. All results indicate that acidity, rather than microwave assistance, is the critical factor that determines the polymerization mechanism and the final nanostructure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3357–3369     

Molybdic acid doped polyaniline micro/nanostructures via a self-assembly process

Molybdic acid (H₂MoO₄, MA) doped polyaniline (PANI) micro/nanostructures were prepared by a self-assembly process in the presence of ammonium persulfate ((NH₄)₂S₂O₈, APS) as the oxidant. The morphology of PANI-MA changed from nanofibers or nanotubes (～160 nm in diameter) to co-existence of nanofibers and microspheres (～3 μm in diameter) and that accompanied an enhancement of the conductivity from 5.42 × 10^?3 S cm^?1 to 2.8 × 10^?1 S cm^?1as the molar ratio of MA to aniline varied from 0.01 to 1.5. With increasing the polymerization time, moreover, the pH value of the reaction solution not only decreased due to sulfuric acid produced during the course of the polymerization, but also accompanied a change in morphology from microspheres to nanofibers. All above-mentioned observations could be interpreted by spherical and cylindrical micelle composed of MA as the “soft-template” in forming the micro/nanostructures.     

A composite polyaniline/graphene–coated polyamide6 nanofiber mat for electrochemical applications

In this study, polyamide6 (PA6) nanofiber mats were fabricated through the electrospinning process. The nanofibers were coated by polyaniline (PANI) using the in situ polymerization of aniline in the presence of graphene oxide. The composite of the PANI/graphene oxide–coated nanofiber mat was treated with hydrazine monohydrate to reduce graphene oxide to graphene, and this was followed by the reoxidation of PANI. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), thermal gravimetric analysis (TGA), tensile strength tests, electrical conductivity measurements, cyclic voltammetry (CV), and charge/discharge measurements were conducted on the composite PA6/graphene nanofiber mats. It was found that the surface of the PA6 nanofibers was coated uniformly with the granular PANI and graphene oxide. Besides, the composite nanofibers showed good tensile and thermal properties. Their electrical conductivity and specific capacitance, when used as a separator in the cell, were 1.02 × 10^?4 S/cm and 423.28 F/g, respectively. Therefore, the composite PANI/reduced graphene oxide–coated PA6 nanofiber mats could be regarded as suitable candidates for application in energy storage devices.     

Fabrication of Polyaniline/Silver Nanocomposite Under Gamma-ray Irradiation

Polyaniline (PANI)/silver composite was one-step synthesized under γ-ray irradiation. The structure of the composite was characterized by Fourier transform infrared spectroscopy, UV-Visible, and X-ray diffraction, which indicated that PANI and face-centered-cubic silver were synthesized under γ-ray irradiation. The reaction mechanism were discussed, which revealed that the PANI was formed by the reaction of aniline cation radicals formed by the reaction of aniline cation and ·OH, and Ag was formed by the reaction of Ag⁺ and e^-_aq. The morphology of the composite consisted of PANI nanofibers and Ag nanoparticles, and the mechanism of the morphology formation was discussed, which revealed that the rapid mixing like polymerization process might play an important role. It was revealed that the transport behavior of the composite well fitted with the variable-range-hopping model in 80-300 K and deviated from the model below 80 K.     

Electrical Properties Investigation in PA12/PANI Composites

Summary: Volume conducting PA-12 based composites powders were chemically prepared by in situ polymerization and aniline doping at room temperature. These kinds of polyamide / PANI composites were investigated regarding their electrical properties. Their ac and dc electrical properties measured in the frequency range of 10⁻²–10⁷ Hz are reported and the frequency dependence of electrical conductivity was investigated as a function of PANI concentration leading to the determination of the conductivity. The experimental conductivity was found to increase continuously with PANI content and explained by percolation theory with a relatively low percolation threshold of about 0.4 wt.%. The dielectric behavior of various PANI polymer composites has been characterized by the critical frequency ω_c (denoting the crossover from the dc plateau of the conductivity to its frequency dependent ac behaviour). Modelling the conductivity behavior versus volume fraction using Slupkowski approach has revealed that the considered parameters are not sufficient to describe the electrical conductivity behavior.     

Polyaniline-coated coconut fibers: Structure,properties and their use as conductive additives in matrix of polyurethane derived from castor oil

Electrically conducting fibers based on coconut fibers (CF) and polyaniline (PANI) were prepared through in situ oxidative polymerization of aniline (ANI) in the presence of CF using iron (III) chloride hexahydrate (FeCl_3.6H₂O) or ammonium persulfate (APS) as an oxidant. The PANI-coated coconut fibers (CF-PANI) displayed various morphologies, electrical conductivities and percentages of PANI on the CF surface. For both systems, a PANI conductive layer was present on the CF surface, which was responsible for an electrical conductivity of around 1.5 × 10⁻¹ and 1.9 × 10⁻² S cm⁻¹ for composites prepared with FeCl₃.6H₂O and APS, respectively; values that are similar to that of pure PANI. In order to modify the structure and properties of polyurethane derived from castor oil (PU) both CF-PANI and pure PANI were used as conductive additives. The PU/CF-PANI composites exhibited higher electrical conductivity than pure PU and PU/PANI blends. Additionally, the PU/CF-PANI composites showed a variation in electrical resistivity according to the compressive stress applied, indicating that these materials could be applied for pressure-sensitive applications.     

One‐pot synthesis of polyaniline doped with transition metal ions using H2O2 as oxidant

Polyanilines (PANIs) doped with Zn²⁺ and Cu²⁺ were synthesized by H₂O₂ oxidative polymerization of aniline in the presence of corresponding metal chloride in solution. The products were characterized by elemental analysis, UV‐Vis‐NIR, FTIR and Raman spectroscopies. Scanning electron micrograph was employed to examine the morphology of PANIs fabricated in the presence of different transition metals. Experimental results showed that transition metal ions had been successfully incorporated into the polymer, and there was a strong interaction between the transition metal ions and the PANI chains. The electrical conductivity of PANI doped with Zn²⁺ and Cu²⁺ is 0.37 and 0.21 S/cm, respectively, which is higher than that of HCl doping PANI corresponding to 0.052 S/cm. The cyclic voltammetric study has indicated that incorporation of metal ions in PANI backbone results in increasing of specific capacitance compared to that of HCl doping PANI. Copyright © 2014 John Wiley & Sons, Ltd.     

Studies on the conducting nanocomposite prepared by in situ polymerization of aniline monomers in a neat (aqueous) synthetic mica clay

The in situ polymerization of the anilinium‐intercalated synthetic mica clay can easily result in an intercalated polyaniline (PANI)/clay nanocomposite. The FT‐IR spectra demonstrated a significant shift for ν_{(C? N)} at 1292 cm^?1 of the templated polymerized and intercalated PANI molecules. A red shift of λ_max for PANI was found from UV–vis spectra. The intercalated PANI also expanded the clay basal spacing seen from WAXD patterns. The degradation rate and temperature of the nanocomposites were found to alleviate and increase compared to neat PANI, respectively. The microscopic examinations including TEM, SEM, and AFM pictures of the nanocomposite demonstrated an entirely different and more compatible morphology. Conductivity of nanocomposite gradually increased with PANI and apparent increase was found when intercalated PANI content reached 40.6 wt %, the possible percolation threshold. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1800–1809, 2008