Molecular simulation of structure formation and rheological properties of mixtures of telechelic and monofunctional associating polymer

Abstract

We study the phase behavior, the characteristic times, and the rheological properties under the steady shear flow of the mixtures consisting of telechelic and monofunctional associating polymers by a coarse‐grained molecular dynamics simulation. The mixtures form the transient networks, the closely packed spherical micelles, and the wormlike micelles. We confirm the molecular origins of the several characteristic times of the mixtures. The dependencies of the characteristic times on the composition ratio between telechelic and monofunctional associating polymers show good agreement with reported experimental results. Under the steady shear flow, the mixtures show the shear thinning induced by the change of the spatial configuration of the micelles. The telechelic associating polymers especially play an important role in connecting the micelles at the shear thinning regime and enhance the steady shear viscosity. Furthermore, at the wormlike micellar region, the mixtures show the second shear thinning initiated by the transformation of the association conformation of the telechelic associating polymers.

Universal scaling and characterisation of gelation in associative polymer solutions

“…These observations are confirmed in Figs. 19, where in subfigure (a) it can be seen that the ratio involving the inter-chain degree of association scales with monomer concentration accord-ing to the prediction of scaling theory even at the highest concentrations examined here, while subfigure (b) indicates that at the scaled concentration c/c * = 1.6, there exists a system spanning cluster, and that the chains are distributed homogeneously across the system, with no sign of phase separation.…”

“…For instance, while in some studies entire micelles are coarse-grained to single particles [14,18], others represent individual polymer chains as bead-spring dumbbells [11,12,30]. Whereas in some recent investigations of the shear flow of associative polymer solutions, bead inertia has been taken into account in the context of Langevin dynamics of bead-spring chains [17,19], in earlier enquiries, associative polymers in shear flow have been modelled as non-interacting dumbbells [12], or non-interacting beadspring chains [13], with beads switching between associated and dissociated states. None of these previous investigations, however, have taken hydrodynamic interactions into account.…”

“…It is not possible currently to specify a priori the particular macromolecular architecture, the precise number, strength and location of the attractive groups, the appropriate solution temperature and concentration, and the particular flow conditions which would achieve optimal product performance. Several computational studies have been carried out aimed at making progress in this direction, i.e., towards improving our understanding of the nonequilibrium response of network structures, and deciphering the connection between molecular topology and macroscopic behaviour, using a variety of different techniques based on coarse-grained bead-spring chain models for polymers [11][12][13][14][15][16][17][18][19]. In this work, we propose a novel alternative approach based on a muliti-particle Brownian dynamics simulation methodology that accounts for hydrodynamic interactions, and which can potentially capture both static and dynamic properties at equilibrium, along with the nonequilibrium rheological response of associative polymer solutions, across a range of concentrations that span the dilute and unentangled semidilute regimes.…”