Comblike polymer electrolyte with main chain glass transition near room temperature

摘要

A new amorphous comblike polymer (CBP) based on methylvinyl ether/maleic anhydride altering copolymer backbone and on oligooxyethylene side chain was synthesized. The dynamic mechanical properties of CBP and its Li salt complexes were investigated by means of DDV-ll-EA type viscoelastic spectrometry. Results showed that there were two glass transitions (α-transition and β-transition) in the temperature range from -100 to 100℃. The β-transition was assigned to oligo-PEO side chains and the temperature of β-transition increases with increasing Li salt content. The α-transition was assigned to the main chain of CBP. The temperature of the α-transition (T_α) is also dependent upon the Li-salt content, but not monotonic. The value of T_α lies between 30-45℃ in the Li salt concentration range studied, near room temperature. It was found that the CBP-Li salt complexes showed an unusual dependence of ionic conductivity on Li salt content. There are two peaks in the plot of the ionic conductivity vs. Li salt concentration, which has been ascribed to the movability of the CBP main chain at ambient temperature. The temperature dependence of the ionic conductivity indicated that the Arrhenius relationship was not obeyed, and the plot of log σ against 1 /(T — T_0) showed the unusual dual VTF behavior when using side chain glass transition temperature (T_β) as T_0.