Lithium perchlorate/poly（ethylene oxide）complex,as potential polymer electrolytes,has attracted much research interests in the past decades,due to its great applicational significance.However,despite of great effort...Lithium perchlorate/poly（ethylene oxide）complex,as potential polymer electrolytes,has attracted much research interests in the past decades,due to its great applicational significance.However,despite of great efforts,the mechanism of ion conducting of the system is still a topic with debates.In this work,the（）13C CP/MAS spectra of a series of PEO/LiClO4 complexes were measured with different compositions.It is found that for the extensively dried samples,the（）13C CP/MAS spectrum can exhibit up to 11 narrow peaks and the characteristics of the spectrum varies greatly with the composition.The（）13C spin-lattice relaxation time（T1）of these narrow peaks are found to be comparable to that of the neat PEO crystalline region,indicating these narrow peaks are corresponding to the complexed crystalline structures.On the other hand,the（）1H T1ρ of the narrow peaks are much longer than that of the neat PEO crystalline region,suggesting that the chain motion of PEO in the complex is greatly restricted due to the interaction between the oxygen of PEO and Li+.The aforementioned 11 peaks are assigned to three complexed crystalline structures.The conductivity of the complex sample decreases greatly when [O]∶ molar ratio decreases to 4∶1,while half of the （）13C peaks that are attributed to one crystalline structure varnish,indicating that there should exist certain kind of correlation between the complexed crystalline structure and the conductivity.展开更多
In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by p...In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by proton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermogravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the curing process, and the curing mechanism was confirmed to be the electrophilic substitution reaction. Compared with the uncured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65% at 600 ℃, which was much higher than 25.02% of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.展开更多
文摘Lithium perchlorate/poly（ethylene oxide）complex,as potential polymer electrolytes,has attracted much research interests in the past decades,due to its great applicational significance.However,despite of great efforts,the mechanism of ion conducting of the system is still a topic with debates.In this work,the（）13C CP/MAS spectra of a series of PEO/LiClO4 complexes were measured with different compositions.It is found that for the extensively dried samples,the（）13C CP/MAS spectrum can exhibit up to 11 narrow peaks and the characteristics of the spectrum varies greatly with the composition.The（）13C spin-lattice relaxation time（T1）of these narrow peaks are found to be comparable to that of the neat PEO crystalline region,indicating these narrow peaks are corresponding to the complexed crystalline structures.On the other hand,the（）1H T1ρ of the narrow peaks are much longer than that of the neat PEO crystalline region,suggesting that the chain motion of PEO in the complex is greatly restricted due to the interaction between the oxygen of PEO and Li+.The aforementioned 11 peaks are assigned to three complexed crystalline structures.The conductivity of the complex sample decreases greatly when [O]∶ molar ratio decreases to 4∶1,while half of the （）13C peaks that are attributed to one crystalline structure varnish,indicating that there should exist certain kind of correlation between the complexed crystalline structure and the conductivity.
基金supported by the National Natural Science Foundation of China(51172285 and 51372277)the Fundamental Research Funds for the Central Universities(14CX02060A,15CX02084A)the Natural Science Foundation of Shandong Province(ZR2011EL030)
文摘In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by proton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermogravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the curing process, and the curing mechanism was confirmed to be the electrophilic substitution reaction. Compared with the uncured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65% at 600 ℃, which was much higher than 25.02% of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.
