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结晶型PEO8∶NaPF6聚电解质中晶区链段的运动

DOI: 10.11938/cjmr20150102, PP. 12-22

Keywords: 固体核磁共振(solid-stateNMR),聚合物链段动力学,电导率,聚氧乙烯(PEO),PEO8∶NaPF6

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Abstract:

利用固体NMR研究了高度结晶的聚氧乙烯(PEO)/六氟磷酸钠(NaPF6)(按照氧钠摩尔比8∶1描述为PEO8∶NaPF6,分子量Mw=1000和6000g/mol)固体聚电解质晶区链段的结构和运动.对于纯PEO来说,晶区链段的构象交换或大角度再取向促使其13C粉末线形从低温的非轴对称(δ33<?δ22<?δ11)变成高温的轴对称线形(δ11=δ22>?δ33).通过变温的13C粉末线形和243K下的二维交换谱,PEO8∶NaPF6晶区链段同样存在大角度再取向,且开启温度也很低(~243K)与PEO接近.这种长程的运动使得PEO8∶NaPF6从低温的类轴对称(δ33<?δ22<?δ11)变成高温的轴对称线形(δ33>?δ22=?δ11),高温线形是PEO高温线形的翻转.与其它PEO/Na(Li)固体聚电解质不同,PEO8∶NaPF6中晶区链段与Na+络合后仍具有很高的运动性(与纯PEO链段的运动性相当),这种高分子链段和Na+协同运动促使Na+沿PEO分子链轴向迁移,提高电导率.

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