Instability of the Microemulsion Channel in Block Copolymer-Homopolymer Blends
Bart Vorselaars, Russell K. W. Spencer, M. W. Matsen
Abstract
Field theoretic simulations are used to predict the equilibrium phase diagram of symmetric blends of AB diblock copolymer with A- and B-type homopolymers. Experiments generally observe a channel of bicontinuous microemulsion (BμE) separating the ordered lamellar (LAM) phase from coexisting homopolymer-rich (A+B) phases. However, our simulations find that the channel is unstable with respect to macrophase separation, in particular, A+B+BμE coexistence at high T and A+B+LAM coexistence at low T. The preference for three-phase coexistence is attributed to a weak attractive interaction between diblock monolayers.
Topics & Concepts
CopolymerMicroemulsionMaterials scienceInstabilityBlock (permutation group theory)Polymer blendChannel (broadcasting)Chemical engineeringThermodynamicsPolymerMechanicsComposite materialComputer sciencePhysicsMathematicsGeometryEngineeringPulmonary surfactantComputer networkBlock Copolymer Self-AssemblyAdvanced Polymer Synthesis and CharacterizationRheology and Fluid Dynamics Studies