四氢呋喃/三氟化硼乙醚混合电解质中咔唑的电化学聚合

ELECTROPOLYMERIZATION OF CARBAZOLE IN MIXED ELECTROLYTE OF TETRAHYDROFURAN AND BORON TRIFLUORIDE DIETHYL ETHERATE

在四氢呋喃/三氟化硼乙醚混合电解质中直接阳极氧化咔唑制备聚咔唑.单体的起始氧化电位为0.92 Vversus SCE,远低于单体在含0.1 mol.L-1Bu4NBF4的乙腈溶液中的起始氧化电位(1.36 Vversus SCE).在此体系中获得的聚咔唑膜具有良好的电化学活性和稳定性,其电导率为7.0×10-3S.cm-1.聚合物可部分溶解于二甲基亚砜等强极性有机溶剂.UV-Vis,FT-IR,1H-NMR证明聚合物共轭长链的形成.该体系中获得的聚咔唑是一种蓝光发射材料,并具有良好的热稳定性.

The purpose of this work is to decrease the amount of boron trifluoride diethyl etherate （BFEE） usually used during the electrochemical polymerization and enhance the stability of as-formed polymer films. The mixed electrolyte of tetrahydrofuran （THF） and BFEE was used because THF can form a new complex with BF3 which is more stable than BFEE and it also can be the solvent for many kinds of aromatic compound which can be electropolymerized. To increase the ionic conductivity of the mixed electrolyte, Bu4 NBF4 was introduced. The ionic conductivity of THF containing 18 % BFEE （by volume） and 0.1 mol· L^-1 Bu4 NBF4 was measured to be 1.25 ×10^-3 S· cm^-1. In this medium, high-quality polycarbazole （PCZ） films were electrosynthesized successfully by direct oxidation of 0.05 mol·L^-1 carbazole. The oxidation potential of carbazole in this medium was measured to be only 0.92 V versus SCE, which was much lower than that determined in acetonitrile containing 0.1 mol·L^-1 Bu4 NBF4 （1.36 V versus SCE）. PCZ films obtained from this medium showed good electrochemical behavior, with electrical conductivity of 7.0 × 10^-3 S·cm^-1. As-formed PCZ films can be partly dissolved in strong polar organic solvents such as dimethyl sulfoxide. For dedoping, PCZ films were treated with 25 % ammonia for 3 days. Then, they were dried at 60℃ for 24 h. The UV-Vis spectra of PCZ showed broader absorption bands mainly at 303 nm, implying wide molar mass distribution. In the fluorescence spectra, the emission peaks of polycarbazole appeared at 415 nm, implying the blue-light-emitting property of PCZ. The FT-IR and ^1H-NMR spectral investigations of PCZ indicated that electrochemical polymerization of carbazole mainly occurred at 3,6 positions, in well accordance with the literature reported previously. Thermal analyses indicated that PCZ films prepared from this medium own good thermal stability. The successful electrosyntheses of PCZ films in this mixed electrolyte may extend the applications of this mixed electrolyte of THF, BFEE and Bu4 NBF4 in the electrochemical science.