Stabilizing undulated lamellae by diblock copolymers confined in alternately adsorbed thin films

Abstract

The self-assembly behavior of AB diblock copolymer confined in staggering alternately adsorbed thin films is studied using the self-consistent field theory (SCFT) and dissipative particle dynamics (DPD), focusing on the emergence and stability of the undulated lamella (UL) phase. Phase diagrams for the volume fraction of blocks, period of the adsorbed pattern and thickness of the confinement are constructed. Our results indicate that the UL phase can be stable in the case with a large period of adsorbed pattern, and is more favorable in the asymmetrical diblock copolymer with volume fraction around f = 0.40, which becomes cylindrical phases (C) with too small f and transforms into tilted lamellae (TL) on the contrary. Furthermore, the number of layers in the UL phases can be regulated by adjusting the period of the adsorbed pattern and the confinement degree of the thin film. In addition, the formation of the UL is verified by DPD simulations. The study demonstrates that the specially confined diblock copolymers provide an efficient route to regulate the stability of the complex UL phases.

Keywords

• Diblock copolymer
• Self-assembly
• Undulated lamellae
• Self-consistent field theory
• Thin film