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首页> 外文期刊>Journal of Applied Polymer Science >NMR Water Self-Diffusion and Relaxation Studies on Sodium Polyacrylate Solutions and Gels in Physiologic Ionic Solutions
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NMR Water Self-Diffusion and Relaxation Studies on Sodium Polyacrylate Solutions and Gels in Physiologic Ionic Solutions

机译：生理离子溶液中聚丙烯酸钠溶液和凝胶的NMR水自扩散和弛豫研究

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摘要

Water self-diffusion coefficients and longitudinal relaxation rates in sodium polyacrylate solutions and gels were measured by NMR, as a function of polymer content and structure in a physiological concentration range of monovalent and divalent cations, Ca~(2+) and Na~+. Several physical models describing the self-diffusion of the solvent were applied and compared. A free-volume model was found to be in good agreement with the experimental results over a wide range of polymer concentrations. The longitudinal relaxation rate exhibited linear dependence on polymer concentration below a critical concentration and showed non-linear behavior at higher concentrations. Both the water self-diffusion and relaxation were less influenced by the polymer in the gel state than in the uncrosslinked polymer solutions. The effect of Na~+ on the mobility of water molecules was practically undetectable. In contrast, addition of Ca~(2+) strongly increased the longitudinal relaxation rate while its effect on the self-diffusion coefficient was much less pronounced.
机译：在单价和二价阳离子，Ca〜（2+）和Na〜+的生理浓度范围内，通过NMR测量聚丙烯酸钠溶液和凝胶中水的自扩散系数和纵向弛豫率，作为聚合物含量和结构的函数。应用并比较了描述溶剂自扩散的几种物理模型。发现在大范围的聚合物浓度下，自由体积模型与实验结果非常吻合。纵向松弛速率在临界浓度以下对聚合物浓度表现出线性依赖性，在较高浓度下表现出非线性行为。与未交联的聚合物溶液相比，凝胶状态的聚合物对水的自扩散和弛豫的影响都较小。 Na +对水分子迁移率的影响实际上是不可检测的。相反，添加Ca〜（2+）可以大大提高纵向弛豫速率，而其对自扩散系数的影响则不那么明显。

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