Synthesis And Electrochromic Properties Of Polyamides Based On Multiple N Centers

Electrochromism refers to the reversible optical transmission or absorption changes during the redox of materials induced by the applied potential.This special property has aroused extensive interests both in academic and industrial fields.Compared with inorganic electrochromic materials,organic materials exhibit many superiorities including fast switching time,low energy consumption,and multiple color changes.In recent years,triphenylamine and its derivatives which are widely used as hole-transport materials show interesting electrochromic behavior and draw considerable attention of optoelectronic field.The propeller-like triphenylamine has an electroactive nitrogen redox center.Introducing of the triphenylamine unit into the polymer backbone results in generation of the electrochromic phenomenon and enhancement of polymer solubility.Therefore,triphenylamine-based electrochromic materials are assumed to afford high performance films which could be applied in technology devices such as smart windows,automatic anti-glazing mirrors and electrochromic displays.In this paper,triphenylamine-containing polyamides based on multiple nitrogen atoms were designed and successfully synthesized.In order to increase the number of nitrogen centers,dimethylamino?NMe₂?group was attempted to be introduced into the polymer side chain.Herein,two series of polyamides were prepared and studied for their electrochromic property.All polyamines showed multicolor changes at the applied voltage.Details are as follows:?1?the diamine monomer containing 4-NMe₂ substituted triphenylamine was synthesized according to the reported route.In addition,the diacid monomer containning 4-NMe₂ substituted triphenylamine was also successfully synthesized.Then polyamide PA-? were prepared by the direct polycondensation reaction of the aboved diamine and diacid monomers.PA-? film displays four reversible redox couples with a low oxidation onset potential at 0.38 V.As the applied potential was increased from 0 to 1.15 V,PA-? film showed four color changes which were ascribed to the oxidation of nitrogen atoms.?2?A new diamine monomer containing 4-NMe₂ substituted tetraphenyl-p-phenylenediamine was synthesized.Novel polyamides?PA-??with 4-dimethylamine?NMe₂?substituted tetraphenyl-p-phenylenediamine were successfully prepared via the polymerization of the new diamine monomer with various diacid monomers.Cyclic voltammograms of PA-? films showed four reversible redox couples with the low oxidation onset potentials of 0.22-0.23 V.And PA-? films exhibited good electrochemical stability in the first oxidation stage.With the applied voltage increasing from 0 to 1.15 V,PA-? films showed four color changes due to the oxidation of nitrogen atoms.Results indicated that the introduction of NMe₂ group in the triphenylamine-based polyamide greatly reduced the oxidation onset potentials of polyamides.More importantly,the prepared polyamides exhibited multicolor electrochromism property because of multiple nitrogen electroactive centers.