DILUTE-SOLUTION PROPERTIES OF CARBOXYMETHYLCHITINS IN HIGH IONIC-STRENGTH SOLVENT

The hydrodynamic characteristics in aqueous solution at ionic strength I = 0.2 M of carboxymethylchitins of different degrees of chemical su bstitution have been determined. Experimental values varied over the f ollowing ranges: the translational diffusion coefficient (at 25.0 degr ees C), 1.1 < 10(7) x D < 2.9 cm(2) s(-1); the sedimentation coefficie nt, 2.4 < s < 5.0 S; the Gralen coefficient (sedimentation concentrati on-dependence parameter), 130 < k(s) < 680 mL g(-1); the intrinsic vis cosity, 130 < [eta] < 550 mL g(-1). Combination of s with D using the Svedberg equation yielded 'sedimentation-diffusion' molecular weights in the range 40 000 < M < 240 000 g mol(-1). The corresponding Mark-Ho uwink-Kuhn-Sakurada (MHKS) relationships between the molecular weight and s, D and [eta] were: [eta] = 5.58 x 10(-3) M-0.94; D = 1.87 x 10(- 4) M-0.60; s = 4.10 X 10(-15) M-0.39. The equilibrium rigidity and hyd rodynamic diameter of the carboxymethylchitin polymer chain is also in vestigated on the basis of wormlike coil theory without excluded volum e effects. The significance of the Gralen k(s) values for these substa nces is discussed. (C) 1998 Published by Elsevier Science Ltd. All rig hts reserved