Impact of Molecular Weight on Fibrillar Methylcellulose Hydrogels

ORAL

Abstract

Methylcellulose (MC) is a partially methoxy-substituted cellulose ether. Aqueous solutions of MC undergo thermoreversible gelation upon heating. Although MC has been a commercial material for over 80 years, the mechanism of MC gelation has been a subject of debate. Recently it has been demonstrated that MC gelation is due to the formation of a fibrillar network, with fibril diameters of ca. 15 nm as measured by small-angle neutron scattering and cryogenic transmission electron microscopy (cryo-TEM). With this new understanding we have investigated the MC molecular weight dependence of the fibrillar network properties. Small amplitude oscillatory shear reveals that the gel modulus increases monotonically with increasing molecular weight. Utilizing cryo-TEM and small angle x-ray scattering (SAXS), we characterize the fibrillar structure. Fitting SAXS patterns to a semi-flexible cylinder model reveals that molecular weight does not impact the structure or concentration of fibrils. We therefore attribute the change in modulus to a decrease in fibrillar network heterogeneity with increasing molecular weight of MC.

–

Presenters

  • Peter Schmidt

    Univ of Minnesota - Twin Cities

Authors

  • Peter Schmidt

    Univ of Minnesota - Twin Cities

  • Paige Owens

    Univ of Minnesota - Twin Cities

  • Frank Bates

    Univ of Minnesota - Twin Cities, Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Materials Science, University of Minnesota

  • Timothy Lodge

    Univ of Minn - Minneapolis, University of Minnesota, Chemistry, Chemical Engineering and Materials Science, University of Minnesota, Univ of Minnesota - Twin Cities, Chemistry and Chemical Engineering & Materials Science, Univeristy of Minnesota, Chemistry and Chemical Engineering & Materials Science, University of Minnesota