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 solution 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 concentrations at which these transitions occur are designated as the overlap concentration c* and the semidilute-concentrated transition concentration c**. Two 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 diffusion motion representing the translational diffusion of the amylose macromolecule is present in the solution. A c > c*, two dynamic motions are observed: a fast diffusion representing the cooperative diffusion and a slow one representing the cluster diffusion. The slow diffusion motion is found to follow the "stretched exponential" diffusion law. The fast diffusion motion is found to have two distinguishable concentration dependence patterns: its concentration dependence at c > c** is stronger than that at c < c**. The relative amounts of these two modes are also analyzed in terms of their concentration dependence.