Arabinoxylan in Water through SANS: Single-Chain Conformation, Chain Overlap, and Clustering

Using small-angle neutron scattering(SANS), we examine the structureand conformational behavior of wheat arabinoxylan (AX) prepared atvarious concentrations in a sodium phosphate aqueous buffer. As foranother major hemicellulose, xyloglucan, we observe a small numberof large clusters surrounded by AX chains that behave exactly as apolymer in good solvent with a Flory exponent & nu; = 0.588. Thefit of the data at high q-values to a standard worm-likechain model gives the persistence length l (p) = 45 & ANGS; and cross section of the chains 2R (c) = 11-12 & ANGS;. In addition, using a dedicated modelingapproach, we extract from the SANS data at the intermediate q-range the correlation length & xi; of the solutionsin the semidilute regime. The decay of & xi; with concentrationfollows a scaling law that further confirms the self-avoiding statisticalbehavior of the AX chains. This first comprehensive study about theproperties of water-soluble AX at different length scales may helpin the development of products and processes involving AX as a substitutefor fossil carbon molecules.