Confinement effects on the miscibility of block copolymer blends

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Block copolymers form ordered nanostructures.
• Confinement in thin films influences these structures.
• Understanding these effects is crucial for materials design.

Purpose of the Study:

• Investigate thin film behavior of symmetric AB diblock copolymers.
• Analyze the impact of hard confining walls with preferential A-component interaction.
• Explore how confinement affects lamellar domain orientation and film thickness commensurability.

Main Methods:

• Utilized self-consistent field theory (SCFT) calculations.
• Examined both neat melts and blends of diblock copolymers.
• Developed a semi-analytical model for coexisting thick and thin monolayers.

Main Results:

• Confinement forces lamellar period (D) to deviate from bulk value (Db) for commensurability with film thickness (L).
• Blends exhibit macrophase separation into multiple thick and thin monolayers for improved fit.
• Observed complex interplay between miscibility and commensurability in confined blends.

Conclusions:

• Confinement significantly alters block copolymer morphology in thin films.
• Macrophase separation offers an additional mechanism for achieving commensurability in blends.
• The findings provide insights into controlling nanostructure formation in thin films.