Self-Consistent Brownian Dynamics Simulation of an Anisotropic Brush Under Shear Flow

✍ Scribed by Alla I. Tupitsyna; Anatoly A. Darinskii; Tatiana M. Birshtein; Victor M. Amoskov; Igor Emri

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 218 KB
• Volume: 13
• Category: Article
• ISSN: 1022-1344
• DOI: 10.1002/mats.200400061

✦ Synopsis

Abstract

Summary: The behavior of an anisotropic polymer brush under a lateral shear flow is considered in the framework of a hybrid method combining a self‐consistent field approach and Brownian dynamics simulation. It is shown that such a flow can induce the compression of an anisotropic brush at shear rates much smaller than those which induce the compression of a conventional isotropic brush. Moreover, a lateral flow can initiate a thermotropic collapse which occurs as an LC phase transition. This collapse takes place at higher temperatures than in the absence of the flow. This can help to find brush compression experimentally. The variation of the internal structure of a brush (density, order parameter, and director orientation profiles, distribution of terminal groups) is also investigated. An anomalous effect of brush densification and ordering near the outer surface is observed. At large shear rates the distribution of chains over their deformation has a bimodal character: one fraction of chains is strongly stretched and another fraction remains unperturbed by the flow. Average characteristics of a brush were compared with predictions of the lattice theory for the box model where the lateral force is applied to chain ends. Satisfactory agreement was observed.

Polymer brush under an influence of lateral flow.

magnified imagePolymer brush under an influence of lateral flow.