Synthesis And Properties Of Electroactive Fluorescent Polymers

Synthesis and properties of polymer light-emitting materials have attracted greatinterest of many scientists, and has been widely used in photoelectric conversion,electroluminescent and other aspects. And the tunable and controllable of thefluorescent properties of fluorescent polymer materials have became the focusconcern among the researchers. Fluorenyl polymer fluorescent materials require themajority of research due to their high luminous efficiency, low driving voltage, lightintensity, long life and other advantages, along with the straightforward orthogonalrelationship between material properties and structure.Conducting polymers have been widely investigated over the past decadesbecause of their promising advantages, such as light weight, flexible large-area filmforming, and unique conductivity. This is due mainly to their unique properties invarious applications, such as electromagnetic interference shielding, anticorrosioncoatings, photovoltaic cells, light emitting diodes, catalysts, energy storage andtransformation, sensors, and so on. Polyaniline (PANI) is one of the most studiedconducting polymers due to its good environmental stability, facility of synthesis,high conductivity, and good redox reversibility with large variety of applications such as rechargeable batteries, corrosion inhibition, gas separation membranes,photovoltaic cell, and electrochromic devices. Oligoanilines with well-definedstructure are the model compound for electronic, optical, and structure of PANI.Recently, a number of work have been focused on the preparation of new polymersbearing oligoaniline segments.It is well known that PANI exists in various oxidation states ranging from areduced LEB, to the half-oxidized EB, to the fully oxidized PNB. Therefore, weenvision that through the adjusting the oxidation degree of the oligoaniline moiety tocontrol the fluorescence intensity of the polymers. In this paper, through themolecular design, we make the oligoaniline moiety and fluorene group introduced tothe main chain of polymers to investigate their photophysical properties.Firstly, A novel multifunctional poly(aryl ether) with both pendant oligoanilineand fluorene groups (PAE-p-OF) was synthesized by nucleophilic polycondensationand characterized by1H NMR, Fourier-transform infrared spectra, and gel permeationchromatography. The polymer showed excellent solubility in common organicsolvents and good thermal stability. Electrochemical and photophysical propertieswere also investigated using cyclic voltammetry, UV–vis, and fluorescencespectroscopies. The obtained PAE-p-OF exhibits satisfactory electrochromicproperties with high contrast value, acceptable coloration efficiency, and moderateswitching times. Moreover, the fluorescence intensity of PAE-p-OF was modulated bycontrolling oxidation degree of oligoaniline moiety, due to the energy migrationoccurring between oligoaniline and fluorene groups.Secondly, a novel multifunctional poly(amic acid) bearing oligoaniline, fluorenegroups (PAAOF) has been prepared through the one-step synthetic route. Thestructure of PAAOF was confirmed via nuclear magnetic resonance (NMR),Fourier-transform infrared spectra (FTIR), and gel permeation chromatography (GPC). Moreover, the electrochemical measurement results revealed that PAAOF materialhave an expected electrochemical activity, and good electrochromic properties withhigh contrast value and satisfactory coloration efficiency. The photophysicalproperties of the as-synthesized PAAOF at various oxidation states were studied. Theresults indicated that the fluorescence of PAAOF could be tuned by modulating theoxidation states of oligoaniline segments. In the fluorescence tuning, the fluorenegroups are fluorophore, and the oligoaniline segments are used as regulatory unit.