Effect of chain flexibility on methylcellulose fibril formation

ORAL

Abstract

Methyl cellulose (MC) is a water soluble cellulose derivative, which upon heating spontaneously forms ~ 15 nm diameter fibrils in aqueous solutions. The lateral size scale of these structures has been shown to be independent of the molecular weight of the MC chains, the concentration, and the temperature of formation, but could be related to MC chain flexibility if the chains are twisting together into a bundle. We have investigated the effects of the persistence length (lp) on MC fibril formation by systematically grafting 800 – 2000 g/mol poly(ethylene glycol) to the backbone. Keeping the grafting densities below 30%, the persistence length increases systematically by as much as a factor of 10 from the added excluded volume produced by the grafts. Upon heating, the resulting fibril structure has been investigated with small angle X-ray scattering, small amplitude oscillatory shear, and atomic force microscopy. At grafting densities below 10%, the fibril radius increases as ~ (lpd)1/2, where d is the average space between chains. For higher grafting densities, the fibril formation is suppressed. These results support a recently proposed MC fibril substructure, in which the chains twist together into a bundle and the diameter is set by MC chain flexibility.

–

Presenters

  • Svetlana Morozova

    • Department of Chemistry, University of Minnesota, Twin Cities
    • Chemistry, University of Minnesota
    • University of Minnesota
    • Department of Chemistry, University of Minnesota

Authors

  • Svetlana Morozova

    • Department of Chemistry, University of Minnesota, Twin Cities
    • Chemistry, University of Minnesota
    • University of Minnesota
    • Department of Chemistry, University of Minnesota

  • Peter Schmidt

    • Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities
    • Chemical Engineering and Material Science, University of Minnesota
    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota

  • S. Piril Ertem

    • Department of Chemistry, University of Minnesota, Twin Cities
    • Chemistry, University of Minnesota
    • University of Minnesota
    • Department of Chemistry, University of Minnesota

  • Theresa M. Reineke

    • Department of Chemistry, University of Minnesota, Twin Cities
    • Chemistry, University of Minnesota
    • University of Minnesota
    • Department of Chemistry, University of Minnesota

  • Frank Bates

    • Department of Chemical Engineering & Materials Science, University of Minnesota
    • Chemical Engineering and Materials Science, University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities
    • University of Minnesota
    • University of Minnesota - Twin Cities
    • Chemical Engineering and Material Science, University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota

  • Timothy Lodge

    • University of Minnesota
    • Department of Chemistry, University of Minnesota, Twin Cities
    • University of Minnesota - Twin Cities
    • Chemistry, University of Minnesota
    • Department of Chemistry, University of Minnesota