Study On The MPEG-g-PAn Copolymer With Ionic And Electronic Conductivity And Its Film

In this dissertation, o-methoxy poly(ethylene glycol) aniline (o-MPEA) was synthesized, then mPEG-g-PAn copolymers were prepared by chemical oxidative copolymerization of aniline and o-MPEA. The compositions, structures, thermal stability and conductibility of the mPEG-g-PAn copolymers were characterized by elemental analysis, FT-IR, UV-visible absorption spectra, TG analyzer and LCR electric bridge. The optimal process conditions of mPEGCI, o-MPEA and the copolymer were discussed respectively. Solubility and film-forming conditions of copolymers were discussed, and the microstructures of the copolymer films were studied by AFM.The results showed that decreasing the molar feed ratio of aniline to o-MPEA (n_An/n_MPEA), the yield of the copolymer decreased and the graft concentration of chain mPEG increased. When the molar feed ratio (n_An/n_MPEA) decreased to a certain extent, the chemical composition of the copolymer varied very little. Increasing the content of side-chain mPEG in the copolymer would make the benzenoid absorption peaks of the dedoped copolymer blue shift greater, while both the quinoid absorption peaks and the characteristic polaron peaks of doped copolymer decreased. The thermal stability of the copolymer was inferior to polyaniline and gradually decreased with the content of side-chain mPEG increasing. The electric conductivity of the HCl-doped copolymer decreased as the content of side-chain mPEG increased, and the electric conductivity with longer mPEG was inferior to the electric conductivity with shorter mPEG. The maximum of ionic conductivities of the copolymer/LiC104 complexes at room temperature may be obtained when [Li+]/[EO] was 0.10. The ionic conductivity increased with MnmpEG increasing when MnmpEc <1000, while the ionic conductivity decreased when MnmPEG> 1000. And the lower the content of the mPEG in the copolymer, the lower the ionic conductivity of the copolymer/LiC104 complex. The relationship among the ionic conductivity (σ_I), the electronic conductivity (σ_E), and the ionic and electronic mixed conductivity (σ_M) was related to EO content. For higher EO content, σ_M was higher than the corresponding σ_I and σ_E, and σ_M was higher than the sum of σ_I and σ_E. The ionic and electronic mixed conductivity showed asynergistic effect.Compared with PAn, the mPEG-g-PAn copolymers were readily soluble in common organic solvents, such as NMP, DMSO, and THF. The mPEG-g-PAn copolymers were expected to increase the water solubility. When EO content reached 8.6x103mol/g, the copolymer became water-soluble. When EO content was equal, the longer mPEG side group, the better the copolymer's water solubility. The film forming of the copolymer was affected by some factors, such as the backing material, the temperature, and the composition of the copolymer or so. The film on polyester or polytel plate was easily peeled off, while the film on glass plate was difficultly peeled off. The smooth and flexible film wasn't obtained at higher temperature. The solubility and film-forming ability increased with the content of mPEG of the copolymer, When y/x ≤ 14, the copolymer became water-soluble, and the smooth and flexible film could be obtained by casting the stable aqueous dispersion of mPEG-g-PAn. All copolymer films present distinct microphase separation. When Mn_mpEG was equal, the microstructure of the copolymer was converted from both continuum to sea island to honeycomb with the content of mPEG increasing, and the film-forming ability increased. When y/x was equal, the microstructure of the copolymer was also converted from both continuum to sea island to honeycomb with Mn_mPEG increasing, and the film-forming ability increased. With equal EO content, the copolymer film all presented the honeycomb microstructure. The honeycomb microstructure of the copolymer film became well proportioned and ordered with Mn_mpEG increasing, and the copolymer film was very smooth and flexible. The copolymer film had a good stability in water. The electric conductivity of the copolymer film was higher th...