NMR Study of Structure and Dynamics of Ionic Multiplets in Ethylene−Methacrylic Acid Ionomers
NMR Study of Structure and Dynamics of Ionic Multiplets in Ethylene−Methacrylic Acid Ionomers
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DOI：
10.1021/ma047647e
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发表时间：
2005-03
期刊：
影响因子：
5.5
通讯作者：
Yuanyuan Jia;A. Kleinhammes;Yue Wu
中科院分区：
文献类型：
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作者：
Yuanyuan Jia;A. Kleinhammes;Yue Wu
用23 Na核磁共振（NMR）和差示扫描量热法（DSC）研究了Na离子中和的乙烯-甲基丙烯酸共聚物离聚体中离子多重态的结构和动力学性质。结果发现，在DSC谱的低温峰的影响，松弛，压缩，和水合作用，并与结构接近离子多重态，而不是多重态本身。离子多重态中Na离子之间的距离是根据二阶矩测量确定的，这表明多重态是由紧密堆积的Na+−O-离子对组成的。23 Na NMR谱线宽度的运动窄化和横向弛豫测量表明，Na或其周围的运动的时间尺度在室温附近是几百微秒的数量级。
Structural and dynamical properties of ionic multiplets in poly(ethylene-co-methacrylic acid) ionomer neutralized with Na ions were studied by 23Na nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). It was found that the low-temperature peak in DSC spectra is affected by relaxation, compression, and hydration and is related to structure in proximity to ionic multiplets, instead of multiplets themselves. The distance between Na ions in ionic multiplet was determined on the basis of a second moment measurement, suggesting that multiplets are composed of close-packed Na+−O- ionic pairs. Motional narrowing of 23Na NMR line width and transverse relaxation measurement indicate that the time scale of motion of Na or its surrounding is on the order of a few hundred microseconds near room temperature.