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

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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.