title: Influence of substrate interaction and confinement on electric-field-induced transition in symmetric block-copolymer thin films.
abstract: In the present work, we study morphologies arising due to competing substrate interaction, electric field, and confinement effects on a symmetric diblock copolymer. We employ a coarse-grained nonlocal Cahn-Hilliard phenomenological model taking into account the appropriate contributions of substrate interaction and electrostatic field. The proposed model couples the Ohta-Kawasaki functional with Maxwell equation of electrostatics, thus alleviating the need for any approximate solution used in previous studies. We calculate the phase diagram in electric-field-substrate strength space for different film thicknesses. In addition to identifying the presence of parallel, perpendicular, and mixed lamellae phases similar to analytical calculations, we also find a region in the phase diagram where hybrid morphologies (combination of two phases) coexist. These hybrid morphologies arise either solely due to substrate affinity and confinement or are induced due to the applied electric field. The dependence of the critical fields for transition between the various phases on substrate strength, film thickness, and dielectric contrast is discussed. Some preliminary 3D results are also presented to corroborate the presence of hybrid morphologies.
authors.affiliation: Institute of Materials Processes, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133, Karlsruhe, Germany.|Institute of Applied Materials-Computational Materials Science, Karlsruhe Institute of Technology, Haid-und-Neu strasse 7, 76131, Karlsruhe, Germany.
authors.forename: Arnab
authors.initials: A
authors.lastname: Mukherjee
authors.affiliation: Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, 208016, Kanpur, India.
authors.forename: Rajdip
authors.initials: R
authors.lastname: Mukherjee
authors.affiliation: Institute of Applied Materials-Computational Materials Science, Karlsruhe Institute of Technology, Haid-und-Neu strasse 7, 76131, Karlsruhe, Germany.
authors.forename: Kumar
authors.initials: K
authors.lastname: Ankit
authors.affiliation: Institute of Materials Processes, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133, Karlsruhe, Germany.|Institute of Applied Materials-Computational Materials Science, Karlsruhe Institute of Technology, Haid-und-Neu strasse 7, 76131, Karlsruhe, Germany.
authors.forename: Avisor
authors.initials: A
authors.lastname: Bhattacharya
authors.affiliation: Institute of Materials Processes, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133, Karlsruhe, Germany.|Institute of Applied Materials-Computational Materials Science, Karlsruhe Institute of Technology, Haid-und-Neu strasse 7, 76131, Karlsruhe, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Nestler