Diffusional Behavior of Poly(γ-benzyl L-glutamate) in Concentrated Solution As Studied by the Field-Gradient 1H NMR Methods

The diffusion coefficient ( D ) of poly( γ -benzyl L-glutamate)(PBLG) in the isotropic, nematic and columnar phases in concentrated solution is successfully determined by the field-gradient 1 H NMR methods. The D values of PBLG molecules in the isotropic phase in 25% PBLG/1,4-dioxane solution are a little bit larger than the identical calculated D values of a PBLG α R -helical chain by the Kirkwood theory, which means PBLG chains move independently in the isotropic phase in 25% PBLG/1,4-dioxane solution. Whereas the D values of PBLG molecules in other phases in 25% PBLG/1,4-dioxane solution and that in all phases in 35% 1,4-dioxane solution are smaller than the identical calculated D values of a PBLG α R -helical chain. It means several PBLG chains move cooperatively in these phases. In the nematic phase, the PBLG molecules diffuse cooperatively as one long rod which containing the several PBLG chains. In the columnar phase, several PBLG chains diffuse also cooperatively keeping with two-dimensional order.