Vertical Segregation in Planar Multiblock Copolymer Brushes Induced by Collapse in a Nonselective Solvent.

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Polymer brushes are crucial in surface modification and nanotechnology.
• Understanding their behavior in different solvent conditions is essential for designing advanced materials.
• Block copolymer behavior in solution influences macroscopic properties.

Purpose of the Study:

• To theoretically investigate the structure of a planar polymer brush made of AB-multiblock copolymers.
• To analyze the brush collapse under poor solvent conditions.
• To determine the effect of block incompatibility on the brush architecture.

Main Methods:

• Utilized Scheutjens-Fleer self-consistent field (SCF) modeling.
• Simulated a planar polymer brush composed of symmetric AB-multiblock copolymers.
• Focused on the collapse transition induced by solvent quality deterioration.

Main Results:

• Incompatible blocks induce intrabrush microphase segregation during collapse, forming alternating A and B enriched layers.
• The layered structure exhibits a novel multimodal free-end distribution.
• Solvent molecules localize at block layer boundaries, causing oscillations in polymer volume fraction.
• Decreased solvent quality reduces the number of layers; longer blocks and higher grafting density enhance layering.

Conclusions:

• Block incompatibility drives microphase segregation in collapsing polymer brushes, creating layered structures.
• The observed phenomena, including multimodal end distribution and solvent localization, offer new insights into polymer brush behavior.
• These findings are relevant for designing stimuli-responsive materials and advanced coatings.