Secondary Polymerization Of Acrylate And Ethylene Oxide Grafted3,4-ethylenedioxythiophene (EDOT), Pyrene And Carbazole

The modern development of conducting polymers （CPs） began in1977as theAmerican scientists Heeger and MacDiarmid and their Japanese colleagueShirakawa discovered that doping chainlike polyacetylene （PA） with iodine endowedthe polymer with metal-like properties, producing coppercolored films with anincrease of conductivity of10orders of magnitude. CPs has attracted great attentiondue to their wide fundamental interest and potential industrial application. At the endof the20th century, the interest in CPs had significantly settled down. However, in2000, Heeger, MacDiarmid, and Shirakawa were awarded the Nobel Price for theirpioneering work in the field of CPs. This distinction excited a new impetus, and amain focus on applications developed in connection with materials research. A greatnumber of different monomers are known that form conducting polymers, such aspolyphenylene （PP）, polyphenylenevinylene, polypyrrole （PPy）, polythiophene（PTh）, and, last but not least, Polyaniline （PANI）. Electrosyntheses of conductingpolymers has been tested as one of the most effective way. In addition, CPs withvarious properties can be achieved via adjusting the electronic character of theπ-orbit along the neutral polymer backbone, including main chain and pendant groupstructural modification. Therefore, design and synthesis of new conjugated polymerwith special functional substituents are highly desirable. In this paper, novelconducting polymers based on acrylate and ethylene oxide functional groupsmodified3,4-ethylenedioxythiophene （EDOT）, pyrene and carbazole weresynthesized by sencondary polymerization. The synthesis conditions, structures andproperties of as-formed polymers were studied in detail.1. A novel acrylate modified3,4-ethylenedioxythiophene （EDOT-AA） wassynthesized, and its free radical polymerization and electrochemical polymerizationled to the formation of corresponding precursor polymer polyacrylate （PAA）functionalized with3,4-ethylenedioxythiophene （EDOT-PAA） and uniformelectrodeposition of acrylate modified poly（3,4-ethylenedioxythiophene）（PEDOT-AA） and polyacrylate modified poly（3,4-ethylenedioxythiophene） （PEDOT-PAA）, respectively. The structure, electrochemical, optical, thermalproperties and morphology of as-formed polymers were systematically investigatedby FT-IR, cyclic voltammetry, UV–vis, thermogravimetry （TG） and scanningelectron microscopy （SEM）. Cyclic voltammetry and spectroelectrochemistry studiesdemonstrated that PEDOT-AA and PEDOT-PAA can be reversibly oxidized andreduced accompanied by obvious color changes from dark brown to transmissiveblue for PEDOT-AA, and from magenta to blue for PEDOT-PAA. The introductionof the acrylate group significantly improves the electrochromic properties of PEDOTand results in high contrast ratios （ΔT%=50.9%at620nm for PEDOT-AA） andcoloration efficiencies (339cm²C^-1for PEDOT-AA and211cm²C^-1forPEDOT-PAA), low switching voltages and fast response time （1.4s for PEDOT-AAand0.9s for PEDOT-PAA）.2. A novel acrylate modified pyrene （Py-AA） was synthesized, and its freeradical polymerization and electrochemical polymerization led to the formation ofcorresponding precursor polymer polyacrylate （PAA） functionalized with pyrene（Py-PAA） and uniform electrodeposition of acrylate modified polypyrene （PPy-AA）and polyacrylate modified polypyrene （PPy-PAA）, respectively. The structure,electrochemical, and optical properties of as-formed polymers were systematicallyinvestigated by FT-IR, cyclic voltammetry and UV–vis spectroscopy. PPy-PAAexerts exemplary activity as fluorescence chemosensor and accomplishes monitoringof important biological targets like Fe³⁺and inorganic phosphate. On binding of Fe³⁺,the fluorescence of PPy-PAA is quenched by97%in label free conditions. Thefluorescence of PPy-PAA is regained back on adding inorganic phosphate withfluorescence enhancement of99%due to the displacement of Fe³⁺from PPy-PAA.This ability of PPy-PAA to accomplish monitoring and estimation of indispensablebiological targets like Fe³⁺and inorganic phosphates rapidly, at very lowconcentration with very high selectivity corroborates the extension of this assaysystem for safe clinical application.3. Novel electroactive conjugated network of poly（ethylene oxide） graftedpolycarbazole freestanding film poly[poly（N-epoxypropyl carbazole）]（PPEPC） wassuccessfully achieved via anionic ring-open polymerization of N-epoxypropyl carbazole （EPC） and subsequently electrochemical polymerization of the resultingpoly（N-epoxypropyl carbazole）（PEPC） in CH2Cl2-Bu4NPF6. Both doped anddedoped PPEPC films were partly soluble in strong polar solvents, such as dimethylsulfoxide. In particular, remarkable enhancement of the fluorescence properties ofdedoped PPEPC was observed in comparison with PEPC, and it was a goodblue-light-emitter with maximum emission at412nm both in solution and solid state.Furthermore, the prepared PPEPC manifested favorable thermal stability and goodmechanical properties, which can be easily bent or cut into variety of shapes.Scanning electron microscopy clearly showed that highly homogeneous PPEPC wasformed on the electrode surface.4. Chemical oxidative polymerization of EDOT-AA and co-polymerization ofEDOT-AA with EDOT in aqueous PSSH solution was successfully carried out toform stable dispersions in water. Compared with homopolymer, the free-standingcopolymer films were formed by coating these dispersions onto PP substrates, theconductivity has been improve with the EDOT increase. When the ratio of EDOT-AAand EDOT was1:5, the electrical conductivity is3.21S cm-1at room temperature.The electrical conductivities of films can be improved by adding DMSO （5wt%） andIPA （30wt%） into dispersions, but the Seebeck coefficients were basicallyunchanged.