Static and dynamic solution properties of corn amylose in N,N-dimethylacetamide with 3% LiCl

Static and dynamic light scattering techniques were used to study the solut ion properties of corn amylose in N,N-dimethylacetamide with 3% (w/v) LiCl. Static properties show three distinguishable regions, which are designated as the dilute, the semidilute, and the concentrated regimes. The concentra tions at which these transitions occur are designated as the overlap concen tration c* and the semidilute-concentrated transition concentration c**. Tw o master curves are used successfully to fit the static data in the dilute and semidilute regimes. Dynamic data show that at c < c*, a single diffusio n motion representing the translational diffusion of the amylose macromolec ule is present in the solution. A c > c*, two dynamic motions are observed: a fast diffusion representing the cooperative diffusion and a slow one rep resenting the cluster diffusion. The slow diffusion motion is found to foll ow the "stretched exponential" diffusion law. The fast diffusion motion is found to have two distinguishable concentration dependence patterns: its co ncentration dependence at c > c** is stronger than that at c < c**. The rel ative amounts of these two modes are also analyzed in terms of their concen tration dependence.