Development of a NMR Probe for the Super-High Magnetic-Field Gradient Spin-Echo and its Application to Polymer Systems

1.超高梯度自旋回波（FGSE-NMR）探针的研制（1）研制成功了最大磁场梯度600 G/cm样品尺寸直径5 mm ×长8 mm脉冲宽度0.03- 50 ms脉冲间隔5- 600 ms产生的磁场梯度用外加电流进行了校准，证实了测量的可靠性。考虑到剩余磁场的影响，确定了脉冲宽度和脉冲间隔的适用范围。这里获得的最大梯度是聚合物领域报道值中最高的。应用于聚合物体系通过以下聚合物动力学的实验研究，证明了使用该探针的FGSE-NMR方法的适用性。(1)聚合物链在聚二甲基硅氧烷混合物中的扩散FGSE-NMR可以分别测量聚合物混合物中各组分的扩散系数。揭示了流体动力学相互作用在熔体链扩散中的作用。(2)高分子链在嵌段共聚物微区中的扩散测定了B-高分子链在A-B和A-B-A型嵌段共聚物微区中的扩散系数。示踪剂链的扩散行为受溶解链在区域中的位置控制。(3)水分子在聚合物凝胶中的扩散测量了水分子在聚（甲基丙烯酸）水凝胶中的扩散系数作为溶胀度的函数，并且发现在较高的溶胀度下，自由水的扩散较慢。

1. Development of a NMR probe for the super-high magnetic-field gradient spinecho (FGSE-NMR)(1) We have succeeded in construction of the probe with following specifications.Maximum of magnetic-field gradient 600G/cmSample size diameter 5mm x length 8mmPulse width 0.03-50msPulse interval 5-600msGenerated magnetic-field gradient was calibrated against applied electric current, and reliability of the measurement was confirmed. Available ranges of pulse-width and pulse-interval were determined by taking the effect of residual magnetic field into account. The maximum gradient attained here is the highest in reported values in the polymer field.2. Application to polymer systemsApplicability of the FGSE-NMR method with this probe was demonstrated through the following experimental studies on polymer dynamics.(1) Diffusion of polymer chains in poly (dimethylsiloxane) mixturesThe FGSE-NMR could measure diffusion coefficient for each component in polymer mixtures separately. Role of hydrodynamic interactions in chain diffusion in melts was revealed.(2) Diffusion of polymer chains dissolved in microdomains of blockcopolymers Was measured diffusion coefficient of B-polymer chains which were dissolved in microdomains of A-B and A-B-A type block copolymers. Diffusion behavior of tracer chains are controlled by location of the dissolved chains in the domain.(3) Diffusion of water molecules in polymer gelsDiffusion coefficient of water molecules in a poly (methacrylic acid) hydro-gel was measured as a function of the degree of swelling, and diffusion of the free water was found to be slower at the higher degrees of swelling.