A symmetric polymer blend confined into a film with antisymmetric surfaces: interplay between wetting behavior and phase diagram

Abstract

We study the phase behavior of a symmetric binary polymer blend which is confined into a thin film. The film surfaces interact with the monomers via short range potentials. We calculate the phase behavior within the self-consistent field theory of Gaussian chains. Over a wide range of parameters we find strong first order wetting transitions for the semi-infinite system, and the interplay between the wetting/prewetting behavior and the phase diagram in confined geometry is investigated. Antisymmetric boundaries, where one surface attracts the A component with the same strength than the opposite surface attracts the B component, are applied. The phase transition does not occur close to the bulk critical temperature but in the vicinity of the wetting transition. For very thin films or weak surface fields one finds a single critical point at ${\varphi }_c=1/2$. For thicker films or stronger surface fields the phase diagram exhibits two critical points and two concomitant coexistence regions. Only below a triple point there is a single two phase coexistence region. When we increase the film thickness the two coexistence regions become the prewetting lines of the semi-infinite system, while the triple temperature converges towards the wetting transition temperature from above. The behavior close to the tricritical point, which separates phase diagrams with one and two critical points, is studied in the framework of a Ginzburg-Landau ansatz. Two-dimensional profiles of the interface between the laterally coexisting phases are calculated, and the interfacial and line tensions analyzed. The effect of fluctuations and corrections to the self-consistent field theory are discussed.

Phys.Rev.E in print

References in corpus (4)

• Symmetric Diblock Copolymers in Thin Films (I): Phase stability in Self-Consistent Field Calculations and Monte Carlo Simulations
• Symmetric Diblock Copolymers in Thin Films (II): Comparison of Profiles between Self-Consistent Field Calculations and Monte Carlo Simulations
• Non-monotonous crossover between capillary condensation and interface localisation/delocalisation transition in binary polymer blends
• Finite size effects on the phase diagram of a binary mixture confined between competing walls

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• Study of first-order interface localization-delocalization transition in thin Ising-films using Wang-Landau sampling
• From Capillary Condensation to Interface Localization Transitions in Colloid Polymer Mixtures Confined in Thin Film Geometry
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• Study of Damage Propagation at the Interface Localization-Delocalization Transition of the Confined Ising Model
• Order-disorder criticality, wetting, and morphological phase transitions in the irreversible growth of far-from-equilibrium magnetic films