Most popular into the era of electrified packaging

2022-09-25
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Entering the era of electrified packaging

since the invention of polymer in the 1970s for more than 100 years, it has been proud of the great advantage of insulation, and has been widely used in industry, especially in the field of packaging. By the 1980s, conductive polymers had been greatly developed due to the injection of high technology, and their application fields were broader

conductive polymer materials have special structure and excellent physical and chemical properties, which make them widely used in optoelectronics, information industry, aerospace and other fields. It has attractive application prospects in anti electromagnetic, anti-static, stealth packaging (anti infrared, anti radar), intelligent packaging and so on. Therefore, conductive polymers are the focus of the research, development, promotion and application of new materials in the 21st century

conductive polymers refer to polymers with conductive function in the main chain structure of polymers, which are generally prepared by doping conjugated polymers with highly delocalized electrons with appropriate electron acceptors (or donors)

conductive polymers are divided into three categories: composite, structural (intrinsic) and ionic. The former is to add conductive substances such as carbon black, fine metal powder or metal plated oxide into the insulating polymer to obtain conductive properties. The ionic type is conductive by adding salt ions such as lithium perchlorate, while the structural type depends on the polymer main chain structure with conductive genes to give conductivity. The three are fundamentally different

characteristics and synthesis of conductive polymers

conductive polymers are basically unsaturated polymers, which are generally synthesized by electrolytic polymerization. It is a conductive polymer with conductive function after certain doping treatment. Its conductivity has the following characteristics: cj/t205 ⑵ 000 points of cross-linked polyethylene (PE-X) pipes for building water supply

① by controlling the doping degree, the conductivity of conductive polymers can change in the insulator metal range (10 to the negative 9th power s/cm-10 to the 5th power s/cm), which is unmatched by any other material. At present, the maximum room temperature conductivity can reach the 5th power s/cm of 10, which is comparable to the conductivity of copper, and the weight is only about 8% of copper; Typical conductive polymers generally have a conductivity of 10 to the 5th power s/cm. ② Conductive polymers can be oriented by stretching, and the conductivity along the stretching direction increases with the degree of stretching, while the conductivity in the vertical stretching direction is basically unchanged, showing strong conductivity directional anisotropy; ③ Although the conductivity of conductive polymers can reach the metal level, its conductivity temperature curve does not show metal characteristics; ④ The carriers of conductive polymers are described by the concepts of soliton, polaron and bipolaron, which are different from the free electrons of metals and the electrons or holes of semiconductors; ⑤ Conductive polymers have a completely reversible process of doping/de impurity, which is the unique property of conductive polymers; ⑥ Conductive polymers have the characteristics of doping with color changes and high third-order nonlinear optical effects, which make them more widely used

the above conductive polymers are generally made of conjugated polymers after doping. According to the principle of "green chemical industry", there are five methods to synthesize conductive polymers at present

(1) chemical synthesis method: prepare the conjugated polymer of the main chain according to the principle of polymer synthesis. Yingshu Shirakawa of Japan uses Ziegler NAND catalyst to polymerize acetylene to polyacetylene (PAC) at low temperature, which is a typical example

(2) electrochemical synthesis: conjugated polymers are obtained according to the principle of mechanochemical synthesis. Many heterocyclic conductive polymers, such as PPy and PTP, are made by electrochemical synthesis. The electrochemical synthesis method can not only make the polymer and doping proceed at the same time, but also easily obtain the conductive film with the required thickness

(3) plasma polymerization: polymerization of monomers under glow discharge. This method has complex process and complex polymer structure. At present, there are few application examples

(4) conjugation conversion method: conversion from non conjugated polymers to conjugated polymers, such as the preparation of parent polymers such as polyacetylene PAC, polyphenylene acetylene PPV and polythiophene acetylene PTV by dehydrochlorination of polyvinyl chloride. Wait

surface view of conductive polymer

PPy

the first conductive polymer was polypyroles, which came out as early as 1916. It is almost forgotten because of its few uses. It was not until 1977 that Japan and the United States successively produced polyacetylene (PAC) with high conductivity that people paid attention to conductive polymers. In recent 10 years, the research and application of polypyrrole have been paid great attention, especially the 3-substituted polypyrrole derivatives have attracted extensive attention

in situ polymerization is usually used to improve the conductivity and processability of PPy. That is, PPy monomer swells and diffuses into the flexible polymer matrix, and then allows in-situ polymerization to prepare high-performance and high-function molecular composites

in the past 10 years, polypyrrole derivatives have developed rapidly. Now, poly (3-alkyl) pyrrolol (3-alkyl) pyrroles, poly (3-alkyl thiophene) pyrrolol (3-alkyl) pyrroles, poly (dialkylated benzene) pyrrolol poly (dihydrobenzo) dipyrroles, as well as the theoretical design of PPy derivatives with small band gap and their use in the replacement of PIY in solid lithium batteries have been synthesized. It is worth pointing out that ring opening porphyrin polymers can be obtained by condensation polymerization of pyrrole and aldehydes. That is, dissolve pyrrole and formaldehyde in a suitable solvent, add acid catalyst to polymerize them under stirring, first generate polypyrrole methane and its derivatives, separate the formed polymer, then dissolve it in a suitable solvent, and use electrolytic oxidation or enzyme catalytic oxidation to move the reaction towards the generation of polypyrrole and its derivatives. A large number of new conductive polymers can be obtained by using this kind of reaction

polythiophene PTP

polythiophenes (PTP or PTH) developed by chemists in 1989 is another useful conductive polymer. For technical reasons, polyalkylthiophene was synthesized in the early stage, because the introduction of alkyl r on the 3 position of thiophene improved the solubility in general organic solvents, but weakened the interaction between PTP molecular chains. With the addition of alkyl R, the solubility of PTP increases, but the conductivity decreases. When R is -ch3, -c2h5, the conductivity of PTI can reach the quadratic s/cm of 10. But this kind of polymer has the disadvantage of low dissolved concentration when doped

structural conductive polymers are insoluble. The water soluble polythiophene synthesized by 3-sulfonic alkyl thiophene can overcome this shortcoming and has self doping, that is, the combination of metal ions m+. With the different relative humidity, the conductivity changes in the negative 7th power of 10 to the second power of 10 s/cm. Doping with Br2 can increase the conductivity to the third power of 10 s/cm, and the band gap is higher than that of polythiophene. The polymer is easy to be made into film with aqueous solution. In order to facilitate preparation, a series of problems such as high molecular weight, mechanical strength, stability, reasonable production cost and production process have been solved, and finally the conductive polymer has entered the practical stage. Nowadays, polythiophene and its derivatives have become new conductive polymers with the characteristics of solubility, high conductivity and good stability

polyphenylene PPP

another kind of conductive polymer with high conductivity, good stability and heat resistance is PPP. By adopting our graphene composite - polyphenylene, it shows interesting electrochemical characteristics, which has been reported to have been used in smart packaging in the United States

generally, there are two methods for the synthesis of PPP: chemical condensation polymerization and electrochemical polymerization

in order to obtain PPP film products, the electrolytic polymerization of benzene is usually used. However, because benzene is extremely stable, it is easy to electrolyze and oxidize it in the presence of supporting electrolyte; Electrolytic oxidative polymerization can be carried out only after Lewis acid additives are added to turn benzene into a complex. In addition, benzene can also be oxidized and polymerized in H2SO4 and liquid sulphite. However, the PPP films obtained by this kind of polymerization are very dark, and there are also some structural defects. In order to improve the polymerization degree and processability of PPP. 1. The pressure testing machine must be checked before use, and the soluble prepolymer conversion process must be adopted. That is, it is formed at the prepolymer stage of its molding processing, and then converted to poly-p-phenylene structure, which is a new method to synthesize PPP from soluble intermediates

polyaniline pan

polyaniline film, which was first successfully developed abroad in 1980, has always been at the forefront of international research because of its many advantages, and has become a new hotspot in the research of conductive polymers. Polyaniline can usually be prepared by electrochemical polymerization. In order to combine the two properties, it is still difficult to prepare polyaniline by legal and chemical polymerization. The conductivity, morphology and properties of polyaniline obtained by choosing different synthesis methods and process conditions are quite different. Since Diaz successfully prepared active polyaniline film by electrochemical polymerization, more in-depth research has been carried out on the electrochemical polymerization and electrochemical properties of polyaniline. According to different conditions, polyaniline prepared by electrochemical method can be film or powder deposited on the electrode surface. Compared with other conductive polymers, pan has the following characteristics: ① diversified structure. The color and conductivity of different molecular structures also change correspondingly; ② Good conductivity. After doping, the conductivity of pan can reach the quadratic s/cm of 10; ③ Good stability. The oxidation resistance and heat resistance of pan are good, and the intrinsic pan decomposes at 360 ℃; ④ Special doping mechanism. The doping of pan is completely different from other conductive polymers. It conducts electricity through proton acid doping. With the good performance of pan, it has been widely used at present

PPV

a conductive polymer successfully developed in the 1980s - PPV (poly phenylene vinylene) is a typical conductive polymer composed of π - π conjugated bonds. It not only has high conductivity, but also has the function of luminous display. It has greatly expanded the prospect of application in the field of packaging. PPV has become one of the most studied conductive polymers in the world since the 1990s because it can only be made into prepolymers and then heated into conductive films in vacuum. There are two ways to modify PPV: one is to introduce substituents on benzene ring; The second is the modification of vinyl. Among the substituents introduced by the former in the benzene ring, alkoxy (r-o-) is studied in detail. Alkoxy substituted poly (p-phenylene acetylene) has the advantages of being soluble, but this kind of substituent has too much influence on its conductivity, which degrades its own characteristics. Therefore, alkyl substituted PPV, such as poly (2,5-heptyl) p-phenylene acetylene (hp-ppv) and other PPV derivatives, has been developed at present, which makes PPV soluble and ensures the good conductivity of PPV. The conductivity can be as high as about 10 to the third power s/cm. Applications have also expanded

Packaging Application of conductive polymers

antistatic

the first application of conductive polymers starts from antistatic. A variety of antistatic and electrostatic shielding materials based on Pty, PTP, PPP and pan have come out one after another. UNIX company of the United States took the lead in blending polyaniline doped with organic sulfonic acid with commercial polymers to make antistatic plastic materials of various colors; As company also made anti static by using organic phosphate human dopant

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