Abstract: In this paper, several swollen sulfate chitosan membranes were investigate by ¹³C CP MAS NMR method for the first time. The results indicate that the molecular conformation and motion of the swollen membrane can quite comprehensively reflect the permeation selectivity. From ¹³C CP MAS NMR spectra of the membrane with different degrees of swelling, the crosslinking strength was observed. The membrane with weak crosslinking has the poor separation ability. From T₁ values of the swollen membrane, it has found that the too fast or slow molecular motion isn't favrable to the permeation selectivity, and there is an appropriate motion rate at which the best permeation selectivity can be approached.

Key words: ¹³C CP MAS NMR, Chitosan membrane, Molecular conformation, Molecular motion