Design, Synthesis And Properties Of Electroactive Polymers

The field of conducting polymers has attracted great academic and industrial interests in the areas of chemistry, physics, engineering and material science since the exciting discovery of high conductivity in doped polyacetylene in 1977. In recent years, it shows a wide range of promising applications in the field of light emitting diodes, rechargeable batteries, anti-static coatings, corrosion inhibitors, organic field-effect transistors, photovoltaic cells, laser and sensors, etc. Among these conducting polymers, polyaniline (PANI) has attracted a special attention due to its excellent environmental stability, easy synthesis, and reversible acid/base doping/dedoping chemistry. Thus, PANI offers the promise of a relatively low-cost conducting polymer that is both stable and processable. In addition, many efforts have been devoted to investigate the PANI structure synthesized by chemical and electrochemical means, and the data reveal that most PANI exhibits an ill-defined structure and has limited properties including solubility, fusibility and stability. Oligoanilines with well-defined chain lengths are model compounds for the electronic, magnetic, optical and structure properties of PANI. Thus the novel properties lead oligoanilines to many potential applications, for instance, as electroactive materials in fabricating electroluminescent, chemically and electrochemically tunable gas-separation membranes, electroactuator devices, rechargeable batteries, anticorrosion and antistatic coatings, biosensor and so on. Therefore design and synthesis of polymers with the well-defined oligoanilines as the side chains or in the main chains by covalent bond to combine the properties of the oligoaniline and desirable polymers properties such as mechanical strength and film-forming are of great interest both theoretically and in application.In this work, we report the synthesis and characterization of several new electroactive copolymers which have alternating conjugated segment (oligoanilines) and non-conjugated segment in the main chain. Furthermore, the size, structure, and properties of the resultant product were characterized by Fourier-transform infrared (FTIR) spectra, 1H NMR, elemental analysis (EA), X-ray powder diffraction (XRD), UV-Vis spectra, cyclic voltammetry (CV), thermogravimetric analysis (TGA), and electrical conductivity measurement.First, we report a novel and simple approach of oxidative coupling polymerization to synthesize electroactive polyamide with a well-defined oligoaniline segment in the main chain. Furthermore, the size, structure, and properties of the resultant product were characterized. For enhancing solubility of the polymer, another electroactive polyamide with flexible alkyl chain in the backbone was successfully synthesized. The resultant polymer can be represented as a genuine molecular composite material and it has excellence solubility in the same solvent. We also prepared a multi-functional polymer with oligoaniline and ferrocene in the main chain by oxidative coupling polymerization. This polyamide not only provides an opportunity for a better understanding of the conducting mechanism of conjugated polymers but also opens a platform to better comprehend the structure–property relationships. Further studies in the regard are currently underway. We have developed a facile approach to an electroactive hyperbranched polyamide by applying an oxidative coupling polymerization within an A2+B3 strategy. There may be significant advantages in the use of hyperbranched PANI materials in comparison to linear structures. Indeed, hyperbranched PANI materials have already attracted considerable attention because of high performance organic conductors, magnets and high dielectric materials. A novel electroactive polymer, copolymer with three kinds of oligoanilines unit in the backbone, has been successfully synthesized and characterized. The conductivity of the copolymer can be achieved up to 5.53×10-5 S·cm-1 when doped with proton acid. The resultant copolymer can be represented as an exciting molecular composite material and it will provide an opportunity for solving the problems that exist in traditional blended conducting polymer composites materials, such as phase separation, migration, extraction, etc. Another electroactive polymer with oligoaniline in the main chain, which exhibiting exciting molecular structure, interesting electrochemical and spectroscopic properties, was prepared by oxidative coupling polymerization. The structure of the polymer was systematically studied by FTIR spectra, 1H NMR, GPC and XRD. The chemical oxidation process of the reduced polymer was monitored by the UV-Vis spectra. Electrochemical activity, thermal properties and electrical conductivity were investigated.A new electroactive polyimide which has alternating conjugated segment (oligoanilines) and non-conjugated segment in the main chain was prepared by oxidative coupling polymerization. Furthermore, the structure of the resultant product was characterized. And the general electrochemical property was studied by cyclic voltammetry. A possible redox process is proposed. The thermal properties were studied by thermogravimetric analysis, and it has an excellent thermal stability. Then we synthesized a functional poly(amic acid) (PAA), synthesized by oxidative coupling polymerization, and successfully obtained polyimide by thermal imidization. The structure and properties of PAA and PI were also investigated.Electroactive poly(aryl ether ketone)s were synthesized by oxidative coupling polymerization. The structure of resulting copolymers was characterized by FTIR, NMR, EA and XRD. And the general electrochemical property was studied by cyclic voltammetry. A possible redox process is proposed. The thermal properties were studied by thermogravimetric analysis; the copolymers have a moderate thermal stability. We have successfully synthesized a novel functional alternating copolymer with well-defined oligoaniline and anthracene unites in the main chain by oxidative coupling polymerization. The copolymer exhibited a blue emission at 426 nm, and the fluorescence intensity depended on the oxidation state of the copolymer. We described the synthesis of polymer having oligoaniline and chiral binaphthyl groups via oxidative coupling polymerization. The chiral polymer was well characterized by FTIR, NMR, EA, XRD, CV, TGA and CD.