Molecular Dynamics Simulation of Xanthan Gum and Locust Bean Gum Blends

Xanthan gum (XG) and locust bean gum (LBG) are naturally occurring polysaccharides that display non-Newtonian and high-viscosity behavior in aqueous solutions. When mixed together, they demonstrate dramatic increase in rheological properties as compared to their individual solutions. Despite the large number of experimental studies on such polymer blends and their individual components, little is known about the mechanism of gel formation when the polymers are mixed. Here, we use coarse-grained molecular dynamics simulations to investigate the mechanical properties of solutions of XG and LBG; as well as a binary mixture of polymers to study the effects of polymer chain concentration and interaction on the structure formation and gelation of these systems. We model polymers as linear chains, with XG being five times longer than LBG. We also studied the effect of adding inorganic sheet-like fillers to each of these polymer systems where addition of nanofillers demonstrated a much larger increase in viscosity due to physical crosslinks between polymer chain and nanofillers. Our results show that the assembly between nanofillers is an important determinant of the final properties of the gel which is facilitated by the types and interactions of the polymers used.