Micelle morphology and chain conformation of triblock copolymers under shear: LA-DPD study

We present an investigation on the morphologies of Pluronic (P123 and P84) micelles subject to a simple shear flow via dissipative particle dynamics simulations in conjunction with the Lowe-Anderson thermostat. The most interesting finding is that the polymer chains take a wide variety of conformations, showing a nearly uniform distribution, rather than either a loop or a bridge as speculated previously. The micellar solutions show shear thinning behavior, and the chains are stretched more easily when the concentration is increased at a given shear rate. For the polymer volume fraction phi <= 0.2, weak flows lead to coalescence of spherical micelles, while rodlike micelles are formed in strong flows. At phi = 0.3, the ellipsoidal micelles are disrupted into smaller spherical micelles in weak flow. For P123 at phi = 0.5, a fragile gyroid-type network formed at equilibrium can be easily disrupted into ellipsoidal micelles of very different sizes by a fairly weak shear force. (C) 2016 Elsevier B.V. All rights reserved.