SMALL-ANGLE SCATTERING CHARACTERIZATION OF DILUTE TO SEMI- DILUTE ARABINOXYLAN POLYSACCHARIDE SOLUTIONS IN WATER
Résumé
We report small-angle neutron scattering (SANS) measurements of aqueous solutions of neutral arabinoxylan (AX) polysaccharide extracted from wheat flour and prepared at increasing concentrations. To maximize the hydration of the chains, the solutions are first prepared at C=1g/L, i.e. below the overlap concentration C*»2-3g/L, and then slowly concentrated using osmotic stress until max. ~200g/L, i.e. well above C*. The SANS data obtained at various concentrations are similar to the one of figure 1, with three distinct q- regions that inform on the structure of the samples at different length-scales: region ❶ that originates from clusters of associated AX chains,1 region ❷ where the chains are in good solvent conditions and form an entangled network of correlation length ξ,2 and the high-q region ❸ where the local conformation and size of the chains are probed (eg. persistence length). The purpose of the talk is to give a full analysis of these SANS results using appropriate models and complementary data of SEC-MALS and rheology. Special focus will be given to the correlation length ξ and its changes with AX concentration. Our group is indeed conducting studies about the diffusion of objects like enzymes in such concentrated AX systems. Knowing ξ is this context is of outmost importance as the mobility of a colloidal species in a polymer liquid is directly linked to ξ and its associated 'tube' or pore size.
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