Effect of oxidants on chemical synthesis and properties of poly(3,4-ethylenedithiathiophene)

摘要

The effects of different oxidants, such as FeCl3, (NH4)2S2O8, H2O2, Ce(SO4)2, and (NH4)2Ce(NO3)6, on the chemical oxidative polymerization of 3,4-ethylenedithiathiophene (EDTT) were investigated in H2O, CH3CN or H2O/CH3CN. It has been found that H2O2 can hardly give visible polymer deposits until catalytic amount of FeCl3 was added. Ce(SO4)2 and (NH4)2Ce(NO3)6 can give relatively rapid rates of polymerization, while poly(3,4-ethylenedithiathiophene) (PEDTT) obtained using FeCl3 and Cerium(IV) salts presented much higher yields. Moreover, properties of PEDTT were also greatly influenced by oxidants. (NH4)2S2O8 and (NH4)2Ce(NO3)6 can give soluble polymers in N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO), and PEDTT synthesized using FeCl3 showed the highest electrical conductivity values (about 0.1∼0.2 S cm−1). The decomposition of PEDTT prepared using FeCl3/H2O2 starts at 490 K, which was higher than those using (NH4)2S2O8 and Cerium(IV) salts. FT-IR spectra measurements indicated the formation of PEDTT molecular chains via α, α coupling of thiophene rings. UV, fluorescence and thermal properties of PEDTT were also characterized.