2010-11-17
10:15 at HCI J 574

Modeling the rheology of complex polymer melts and supramolecular polymeric assemblies

Evelyne van Ruymbeke

Chimie et Physique des hauts polymères - Université catholique de Louvain, Belgium

We present a general coarse-grained model for predicting the linear viscoelasic properties of branched polymers from the knowledge of their molecular structure and three viscoelastic parameters, i.e. the Rouse time of an entanglement segment, the plateau modulus and the entanglement molecular weight. The model uses the ingredients of the tube-based theories of McLeish and co-workers, and its implementation is based on a time-marching algorithm. With proper account of polydispersity and use of macromolecular coordinates for the diffusion of the branching points, successful description of a wide range of rheological data of H, pom-pom, tree-like or comb polymers is obtained. We are now extending this approach in order to predict the nonlinear rheology of polymer melts. Then, using the same framework, we investigate the linear viscoelastic response of transient networks obtained by supramolecular interactions between linear and star polyisoprenes (of varying molar mass above the entanglement limit). This requires accounting for the association status of the chains via the dipolar interactions at each time step. A good agreement of the predictions with two adjustable parameters (the average times when two dipolar pair remain associated or free, respectively) is obtained, which suggests design criteria for choosing supramolecular assemblies.