Montana State University
MR Lab Group
Montana State University
306 Cobleigh Hall
P.O. Box 173920
Bozeman MT 59717-3920

Directors:
Sarah Codd
scodd@coe.montana.edu

Joseph Seymour
jseymour@coe.montana.edu

Research Projects

Gels

Polymer gels are chemical or physical cross-linked networks of flexible polymer molecules. Biopolymers tend to form physically cross linked gels with weaker cross-link bonding energy than covalent chemical bonds. Non-covalent physical cross-links are of multiple type, e.g. ionic interactions, hydrogen bonds, dipole-dipole interactions and London dispersion forces, which fluctuate in number and position with time and temperature. The description of physical gels is more complex and the sol-gel transition is not sharp but depends upon the stability, strength and reversibility of the bonds. This research studies the molecular dynamics using MR relaxation and diffusion in physical gels. Initial research is looking at thermoreversible Xanthan Gum (XG)/Locust Bean Gum (LBG) biopolymer gels XG/LBG gels are useful for drug delivery applications and can be used to develop experimental protocols to better understand the extracellular polymeric substance (EPS) of biofilms. Classic and Rheo-NMR rheological measurements will help understand more about the stress-strain relationship of the mixture and its viscoelastic behavior which, in turn, is a key physical property related to the structure of the gel and its transport properties such as molecular diffusion of solvent like drugs in the gel. MR data obtained can be spatially resolved and elucidate polymer network connectivity and molecular translational and rotational mobility. This molecular dynamics information combined with rheology will be helpful to begin understanding physical gels at a molecular level to connect gel structure to function.