Modified models of polymer phase separation

Douglas Zhou, Pingwen Zhang, and Weinan E

Phys. Rev. E 73, 061801 – Published 12 June 2006

Abstract

In this paper we discuss continuum models of phase separation in polymer solutions, with emphasis on the thermodynamic foundation of these models. We demand that these models obey a free energy dissipation relation, which in the present context plays the role of the second law of thermodynamics, since the system is isothermal. First, we derive a modified two-fluid model for viscoelastic phase separation from nonequilibrium thermodynamics. Then we study the special case when only diffusion is present, and hydrodynamic effects are neglected. Numerical results demonstrate that our models show better stability properties and at the same time reproduce the expected physical phenomena such as volume shrinking and phase inversion. Our findings suggest that these important phenomena are caused by a diffusional asymmetry of the constituent molecules.

Received 28 September 2005

DOI:https://doi.org/10.1103/PhysRevE.73.061801

Authors & Affiliations

Douglas Zhou¹, Pingwen Zhang^1,*, and Weinan E^1,2,†

¹LMAM, Peking University, Beijing 100871, People’s Republic of China and School of Mathematical Science, Peking University, Beijing 100871, People’s Republic of China
²PACM, Princeton University, Princeton, New Jersey 08544, USA and Department of Mathematics, Princeton University, Princeton, New Jersey 08544, USA

^*Email address: pzhang@pku.edu.cn
^†Email address: weinan@math.princeton.edu

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Vol. 73, Iss. 6 — June 2006

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Physical Review E

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