Research progress of the hottest conducting polyme

2022-09-22
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Research progress of conductive polymer polyaniline and its composites

Abstract: the outstanding advantages of conductive polymers are not only the electrical and optical properties of metals and inorganic semiconductors, but also the flexible mechanical properties and processability of organic polymers, as well as electrochemical redox activity. Macdiamid, Heeger and Shirakawa Yingshu jointly won the 2000 Nobel Prize in Chemistry for their outstanding contributions to the discovery and development of conductive polymers. Polyaniline has become one of the most promising conductive polymers because of its outstanding advantages, such as simple preparation (mass production through chemical oxidation polymerization), low cost, good stability, and the ability to prepare conductive polyaniline solution

1 polyaniline derivative

polyaniline (Pan) has excellent electrochemical activity and environmental stability, but the processing performance, solubility, poor physical and mechanical energy and other problems greatly limit the application and development of pan. Modifying and modifying the structure of pan can effectively improve the above defects, so it has become the main direction of Pan research at present

introducing mesogenic units into the ortho position of aniline ring is an important method to obtain liquid crystalline polyaniline derivatives. This kind of liquid crystalline polyaniline is an opportunity for the development of non-ferrous metals in China. The preparation of derivatives is to synthesize ortho ring substituted aniline monomers with mesogenic groups, and then obtain liquid crystalline poly ortho ring substituted aniline through interfacial polymerization. The liquid crystal compound 1-bromo-10 - (p-4-n-amyl-cyclohexyl-phenol) - decane was introduced into the ortho position of aniline ring, which could be etherified with o-hydroxy-n-acetylaniline to obtain mesomorphic group ortho ring substituted aniline. Polymerization is carried out at the interface between water and organic solvent layer. The water contains ammonium persulfate and perchloric acid, and the organic solvent is chloroform. Typical polymerization reaction examples are as follows: at 0 ℃, ortho ring substituted aniline, perchloric acid, chloroform, etc. are placed in a flask, stirred and mixed evenly, and the ammonium solution of carbon fiber body that can be used in automobiles is added to the mixture drop by drop, and the oxidized polyaniline derivative is obtained after reaction for 24h. Neutral polyaniline derivatives can be obtained after reduction with ammonia solution. The resulting polymers have good solubility and can be dissolved in organic solvents such as chloroform, tetrahydrofuran, NMP, etc

liquid crystalline polyaniline derivatives will also be synthesized if liquid crystalline units are introduced into the methylene bridge. The synthesis method is usually based on Rothemund reaction, which is the dehydration polycondensation of diphenylamine and liquid crystal compounds whose terminal group is benzaldehyde in the presence of sulfuric acid

2 polyaniline copolymer

using the excellent conductivity of polyaniline, copolymerization with other structural and functional materials in a variety of ways, can be used to a variety of new polymer materials, and used in aerospace, automotive, microelectronics, communications, textiles and many other fields, has gradually become a research hotspot in recent years

2.1 coal based polyaniline conductive composite

Xi'an Science and technology Changshu national high tech Industrial Development Zone is located in the core region of the Yangtze River Delta. Firstly, using the special aromatic ring structure characteristics (electrical properties), pore structure characteristics (swelling) and acidic side group structure characteristics of coal, coal is used as the matrix and as a macromolecular proton acid dopant to initiate the in-situ polymerization of aniline to prepare coal based polyaniline conductive composite. This composite material is expected to become a new and cheap conductive filler, which can be used to fill various polymers to prepare conductive composites, so as to solve the problem of poor processability of Polyaniline in practical applications

2.2 pan-peg6000-pan triblock copolymer

peg is a flexible polymer, and its introduction is conducive to polyaniline doping. Mao LianBo et al. Dissolved the triblock copolymer in N-methyl pyrrolidone (NMP), N, n-dimethylamide (DMF), chcl2 (DCM) and ethanol respectively, and prepared a dilute solution with a concentration of about 1.5mg/ml. After magnetic stirring at room temperature for 4h, their self-assembly behavior was observed under scanning electron microscope. It was found that the triblock copolymer could be assembled into different morphologies in different solvent types supporting 7mm to 100mm parts, It mainly depends on the compatibility difference between the solvent and the two segments

2.3 carbon nanotube/polyaniline composites

Zeng Xianwei of Beijing University of chemical technology and others prepared carbon nanotube/Polyaniline Composites by in-situ polymerization. Put an appropriate amount of carbon nanotubes into a three port flask filled with deionized water and stir at high speed for a period of time. Take an appropriate amount of aniline and dissolve it in 50ml de ionized water. Adjust the pH to 1 ~ 2 with HCl, and then add it into a three necked flask to stir well. Take an appropriate amount of (NH4) 2S2O8, prepare a 5oml solution with removed water, control the molar ratio of polyaniline to (NH4) 2S2O8 to be about 1:1, slowly add the aqueous solution of (NH4) 2S2O8 to the mixed solution of aniline and carbon nanotubes under ice water bath conditions, and make it react at 0oC for 30min. After the reaction, the product is filtered and washed, and dried under vacuum to prepare carbon nanotubes/polyaniline composites. It can be seen that in the carbon nanotube/polyaniline composite, polyaniline completely wraps the carbon nanotube and forms a polyaniline layer on the surface of the carbon nanotube

2.4 pva/pani conductive composite fiber

conductive fabric made of conductive fiber has excellent functions of conducting electricity, heating, shielding, absorbing electromagnetic waves, etc., and is widely used in conductive and conductive work clothes in electronic and power industries; Electric heating clothes and bandages in the medical industry; It is also widely used in electromagnetic wave shielding covers in aviation, aerospace and precision electronics industries

Li Lei of Sichuan University and others impregnated polyvinyl alcohol (PVA) fibers with good mechanical properties with aniline (ANI) in the swelling state to prepare pva/pani conductive composite fibers. The PVA fiber sample is put into 1 mol/l hydrochloric acid (1mol/l) solution of ani monomer, soaked for 3h, taken out, quickly put into a solution containing ammonium persulfate (1.0g) and 1mol/l hydrochloric acid, and polymerized at OC for 2h to obtain pva/pani conductive composite fiber

2.5 polyaniline coated short carbon fiber

the surface of modified SCF (pascf) directly coated with polymer is loose and peeled under mechanical action. After oxidation treatment, the surface of modified SCF (paoscf) coated with polyaniline is dense and uneven, and the surface roughness is significantly increased, thereby increasing the effective contact area between the SCF surface and the base resin, which is conducive to resin infiltration, The physical anchoring effect is significantly enhanced. This is mainly due to the increase of the content of - c00h, - 0h and other functional groups on the SCF surface treated by nitric acid oxidation, which improves the wettability and polarity of the fiber surface and increases the chemical bonding point, thus improving the wetting and chemical bonding of aniline monomer on the fiber surface during the in-situ polymerization process, effectively improving the adhesion of polyaniline on the fiber surface and forming a relatively dense coating

references

[1]hiromasa goto and Kazuo Akagi synthesis and properties of polyaniline derivatives with liquid crystal, macrolecules 2002:35,

[2] Wang Meijian, Study on the conductivity of Du Meili coal based polyaniline composites modern plastic processing and application 2007: 18 (6) 5 ~ 8

[3] Yu Dongxiu, Chen Mingtao, Wen Xiufang, Cheng Jiang, Yang Zhuoru mechanism and dispersion stability of polyaniline coated short carbon fibers Journal of South China University of Technology (NATURAL SCIENCE EDITION) 2007:35 (7) 72 ~ 75 (end)

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