Study of Segmental Motion in Polymer Solutions by Nuclear Magnetic Resonance

概要

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Experimental and theoretical considerations of segmental motion in chain molecules were studied from the view point of nuclear mognetic resonance. By using the high resolution type spectrometer of NMR, it was verified that the line widths of phenyl group and CH_2 group in polystyrene-CCL_4 solutions were almost all independent of chain lengths in dilute solutions. These values of line widths indicate that the so-called segmental motion in a chain is performed in the unit of about ten monomers. The segmental motion hindered by the potential field was discussed by using the generalized theory of Brownian motion. The influences of restricted motion upon T_1 and T_2 in polyisobutylene-CCL_4 solution are examined. The results of our theory are as follows. The activation energy of segmental motion tends to the activation energy of solvent when the concentration of polymer decreases. The value of activation energy increases with the increase of concentration of polymer. These results are in a good agreement with these of mechanical and dielectric measurements. Furthermore, the values of hindering potential are calculated from the data of T_1 and T_2 in PIB solutions. Finally, it is verified that the rigidity of polymer solution in the high frequency measurement should be caused by the potential field hindering the micro-Brownian motion of segment.
社団法人日本物理学会の論文
1959-06-05