Evaluation of viscosity and shear stress in a telechelic polymer when various shear rates are applied

Abstract

We present the results of molecular dynamics (MD) simulations of bead and spring models of associating polymers at melt-like densities. We consider telechelic polymers of general formula AB12A at different values of shear rate. Under bulk conditions, A···A associations occur, leading to the construction of clusters or micelles that are interconnected by a number of bridging chains. This results in a physical gel or a reversible network, and the corresponding micelles assume different forms depending on the interaction strength. Whenever a low shear deformation is applied, the clusters are broken and there is a phase transition similar to that from a gel to a common non-Newtonian fluid. However, if the applied shear is increased, the chains stretch themselves (in a manner similar to nematic liquid crystal ordering) in a different way from what is seen without shear. In this work, we calculate the stress needed to yield a required deformation.