Concentration enrichment of urea at cellulose surfaces: results from molecular dynamics simulations and NMR spectroscopy
2012 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, no 1, 1-12 p.Article in journal (Refereed) Published
A combined solid-state NMR and Molecular Dynamics simulation study of cellulose in urea aqueous solution and in pure water was conducted. It was found that the local concentration of urea is significantly enhanced at the cellulose/solution interface. There, urea molecules interact directly with the cellulose through both hydrogen bonds and favorable dispersion interactions, which seem to be the driving force behind the aggregation. The CP/MAS 13C spectra was affected by the presence of urea at high concentrations, most notably the signal at 83.4 ppm, which has previously been assigned to C4 atoms in cellulose chains located at surfaces parallel to the (110) crystallographic plane of the cellulose Iβ crystal. Also dynamic properties of the cellulose surfaces, probed by spin-lattice relaxation time 13CT 1 measurements of C4 atoms, are affected by the addition of urea. Molecular Dynamics simulations reproduce the trends of the T 1measurements and lends new support to the assignment of signals from individual surfaces. That urea in solution is interacting directly with cellulose may have implications on our understanding of the mechanisms behind cellulose dissolution in alkali/urea aqueous solutions.
Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2012. Vol. 19, no 1, 1-12 p.
Cellulose, Urea, Solid state NMR, Molecular dynamics simulation
IdentifiersURN: urn:nbn:se:umu:diva-50768DOI: 10.1007/s10570-011-9616-xOAI: oai:DiVA.org:umu-50768DiVA: diva2:468617
Published online 15 November 20112011-12-212011-12-212012-02-14Bibliographically approved