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Electrochromic Properties of Copolymer Films Based on EDOT |126213-50-1| and P3C Copolymer

2017-04-06 来源:亚科官网
6 April 2017
  Electrochromic is the phenomenon of reversible and stable changes in the optical properties such as transmittance, reflectivity and absorptivity of the material under the action of current or electric field, it shows reversible change of transparency and color in appearance. The material with electrochromic properties is called electrochromic material, which is mainly composed of inorganic metal oxide, organic small molecule and conductive polymer. Among them, the conductive polymer electrochromic material has become a hotspot in recent years because of its wide variety of structures and obvious color change. Recently, researchers have 3,4-ethylene dioxythiophene (EDOT) and other monomers copolymerization to study the electrochromic properties.
  Among the many conductive macromolecules, PEDOT is an electrochromic material with fast response speed and high contrast, and its excellent electrochromic properties have aroused the interest of most scholars. Under the action of the external voltage signal, PEDOT undergoes the reversible change of the conjugate structure by the doping of anion and the electron injection, which shows the reversible transformation between the transparent blue at oxidation state and the mazarine at reduction state.
  But PEDOT only have two kinds of color changes at different potentials, that is, dark blue under the negative potential and light blue under positive potential. In order to enrich the color of electrochromic materials, Zhang Cheng et al. [1] made EDOT and pyrrole-3-carboxylic acid (P3C) copolymerization to achieve the target. The authors obtained four kinds of poly(3,4-ethylenedioxythiophene-pyrrole-3-carboxylic acid) by electrochemical copolymerization of EDOT and P3C in the ratio of 1:1,3:1,5:1,10:1, and named P(EDOT:P3C)-1, P(EDOT:P3C)-3, P(EDOT:P3C)-5 and P(EDOT:P3C)-10, respectively.
  EDOT and P3C are located in the ultraviolet region, and the absorption wavelength of the copolymer is obviously redshift. P(EDOT:P3C)-1 has the maximum absorption peak at 500nm, P(EDOT:P3C)-3 is about 520nm, the maximum absorption peak wavelength of P(EDOT:P3C)-5 is 561nm, and the maximum absorption peak wavelength of P(EDOT:P3C)-10 is 585nm. The red shift of the polymer absorption peak indicates that the conjugate length of the polymer molecular chain is greater than that of the corresponding monomer, and also demonstrates the occurrence of monomer polymerization.
  The electrochemical analysis showed that the four copolymer films showed at least three color changes at different voltages. With the gradual increase in voltage, the polymer film appears color change from lavender to blue. P(EDOT:P3C)-1 has the most obvious color change at different voltage. The absorption peak is at 500nm in the neutral state, the polymer film exhibits reddish brown color. When the voltage rose to 1.2V, absorption peak weakened at 500nm and enhanced at 700~1100nm, the color is also changed to blue; The absorption peak of (EDOT:P3C)-3 and P(EDOT:P3C)-5 were at 523 and 561nm in the neutral state, respectively, the phenomenon is due to the polymer conjugate structure caused by the increase of EDOT units, when the polymer appears purple, when the voltage rose to 1.2V, the polymer film is also enhanced in the vicinity of 700~1100nm, the color of the polymer film occurs changes from light purple to pale blue. P(EDOT:P3C)-10 appears strong absorption at 582nm, gradually close to the absorption of PEDOT in this band, when the polymer film showed dark purple.
  Four EDOT and P3C-based copolymer films were prepared by electrochemical copolymerization. The results showed that the four copolymer films had excellent electrochromic properties, compared with PEDOT, and showed more abundant color changes. P(EDOT:P3C)-1 is the most prominent with richer color change, better electrochemical activity and higher optical contrast. In addition to its unique optical and electrical properties, pyrrole-3-carboxylic acid (P3C) is also low-costs, it has a wide range of applications.
[1] Lv Yaokang, Liu Youyou, Pan Yun, et al. Preparation, Characterisation and Electrochromic Properties of Copolymer Films Based on 3,4-Ethylenedioxythiophene and Pyrrole-3-Carboxylic Acid. Chemical Journal of Chinese Universities, 2017, 38, 484-494.
Related links: EDOT
Edited by the Editorial Office of Suzhou Yacoo Science Co., Ltd.