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

1. 一种用于超高磁场梯度旋回（FGSE-NMR）的核磁共振探针的研制(1)我们已经成功地构建了具有以下规格的探针。最大磁场梯度600G/ cm样品尺寸直径5mm x长度8m脉冲宽度0.03- 50m脉冲间隔5- 600ms根据外加电流校准产生的磁场梯度，并证实了测量的可靠性。考虑残余磁场的影响，确定了脉冲宽度和脉冲间隔的可用范围。这里获得的最大梯度是聚合物领域报道值中最高的。在聚合物体系中的应用FGSE-NMR方法与该探针的适用性通过以下的聚合物动力学实验研究证明。(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每种组分的扩散系数。揭示了流体动力相互作用在熔体链扩散中的作用。(2)聚合物链在嵌段共聚物微域内的扩散测量了b -聚合物链在A-B型和A-B- a型嵌段共聚物微域内的扩散系数。示踪链的扩散行为受示踪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定了水分子在聚甲基丙烯酸水凝胶中的扩散系数与溶胀程度的关系，发现溶胀程度越高，自由水的扩散速度越慢。

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.