Yanmin Wang

Polyaniline is a kind of polymer material with excellent electrochemical performance, and it stands out among a number of conductive polymer materials owing to its low cost, easy availability of raw materials, and excellent physical and chemical properties. However, the poor processability of polyaniline impedes its broad application. Preparing nanosized structure and introducing big molecular organic acids as dopant are practical strategies to solve this problem. Here using ammonium persulfate as oxidant, sodium dodecyl sulfate as surfactant, and 3,5-dinitrobenzoic acid as doping acid, polyaniline nanotubes were successfully prepared via emulsion polymerization method and characterized by various measurements. The influence of aniline concentration on the morphology and property of the product was explored. The polymerization mechanism of polyaniline nanotubes was discussed in detail based on the analysis of the microscopic morphology. As the concentration of aniline monomer increases, the position of the characteristic absorption peak in the infrared spectrum of the polyaniline main chain remains almost unchanged, but the ratio of benzene to quinone gradually increases. Along with the increasing aniline concentration, the crystallinity of polyaniline gradually decreases from 56.21% to 40.37%. In addition, the optimal conductivity is 2.05×10⁻² S/cm when the concentration of aniline monomer is 0.5 mol/L.

Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI) composite and carboxylated multi-walled carbon nanotube (MWCNT-COOH)/PANI composites are fabricated via in situ chemical oxidative polymerization method. The crystallinity, chemical structure and morphology of the composites are investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and field-emission scanning electron microscopy (FESEM), respectively. Based on the different morphology, the formation mechanism of the composites is proposed and the influence of the morphology on the electrochemical performance is predicted. The electrochemical properties of the composites are evaluated by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The MWCNT-COOH/PANI composite electrode shows higher specific capacitance than that of the MWCNT/PANI composite, as can be ascribed to the interpenetrating network structure of the MWCNT-COOH/PANI composite and the co-doping of DBSA and MWCNT-COOH. The MWCNT-COOH/PANI composite with 15% MWCNT-COOH presents the best electrochemical performance owing to the synergistic and comprehensive effect of the components. Using functionalized MWCNT provides an efficient approach to prepare high-performance composite materials for electrical energy storage fields.

The application of polyaniline (PANI) in various fields is greatly limited by its poor solubility in water.Many methods which could elevate PANI water-soluble ability were used by researchers to expand its application range. In this paper, the research progress of the commonly used preparation methods of water-soluble PANI in recent years is reviewed. The main preparation methods of water-soluble PANI are categorized into four types including monomer modification, controlling the polymerization process, introducing water-soluble groups or substances, macromolecular reaction. They are composed of aniline derivative method, copolymerization, emulsion polymerization method, dispersion polymerization method, acid doping method, compound method, ATRP method. The principles of various methods to achieve water-solubility of PANI are introduced, the research on each preparation method reported before are introduced and their advantages and disadvantages are summarized.

ZnO nanorods have been widely used to detect low-concentration gases due to its range of conductance variability, response toward both oxidative and reductive gases, and highly sensitive and selective properties. In this chapter, the fabrication methods of ZnO nanorods, their controllable growth, their different configurations, their modification for improving sensing property, and their composites for gas sensors are thoroughly introduced. The synthesis methods to fabricate ZnO nanorods consist of hydrothermal method, microemulsion synthesis, microwave-assisted hydrolysis preparation, gas-solution-solid method, spray pyrolysis, sonochemical route, simple solution route, and so on. The controllable fabrication of ZnO nanorods can be realized by control growth, selective growth, and diameter regulation. Different structures formed by ZnO nanorods include cross-linked configuration, flowerlike structure, and multishelled hollow spheres and hollow microsemispheres, as influence their sensing properties. ZnO nanorods can be modified by doping, functionalization, decoration, and sensitization for enhancing the sensing property. ZnO can be combined with graphene, carbon nanotubes, SnO2, In2O3, and Fe2O3 to form core-shell composites for gas sensor.

Conductive polymers (CPs) for sensors present numerous advantages such as high sensitivity, short response time, room temperature operation, and the possibility of tuning both chemical and physical properties by using different substituents. Therefore, sensors based on CPs and their composites have attracted much attention from researchers. The CPs used for sensors mainly consist of polyaniline, polypyrrole and poly(3,4‐ethylenedioxythiophene) etc. In this review, the fabrication, sensing performance, mechanism and perspectives of sensors based on CPs and their composites are thoroughly summarized. The CPs and their thin films were prepared under different polymerization conditions and used as various sensors. CP composites combine the advantages of CPs and other sensing materials such as carbonaceous materials, metal oxides, metals etc., and their sensors demonstrate a high sensing performance due to the synergistic effect of the components. Finally, the perspectives and development trends of sensors based on CPs and their composites are introduced. © 2019 Society of Chemical Industry

Composites comprised by polyaniline doped with itaconic acid and tin oxide (SnO2) were prepared by in situ polymerization method. Aniline was polymerized in the presence of SnO2to form...

Itaconic acid–doped polyaniline (PANI)/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared via in situ polymerization for microwave absorbing materials. The interaction between PANI and MWCNTs and the influence of MWCNTs loadings on the properties of their nanocomposites were investigated by various measurements, such as Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, thermogravimetric analysis, and network analyzer. The electron delocalization in the composites is associated with the π–π* interaction between the surface of MWCNTs and the quinoid rings of PANI. The conductivity, crystallinity, and thermal stability of the nanocomposites with different morphologies have been increased due to the introduction of different MWCNTs loadings. Moreover, the microwave-absorbing property of itaconic acid-doped PANI in the reflection loss value and in different frequency areas is improved by the incorporation of MWCNTs. The nanocomposites are promising candidates in microwave absorption applications.