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Stabilizing hexagonally close-packed phase in single-component block copolymers through rational symmetry breaking.
Zhanhui Gan1,2, Zhuoqi Xu1, Kun Tian3
1South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou, China.
Nature Communications
|August 3, 2024
Summary
Researchers achieved the hexagonally close-packed spherical phase in single-component block copolymers by breaking molecular symmetry. This breakthrough provides experimental evidence for a predicted structure, advancing fundamental polymer science.
Area of Science:
- Polymer Science
- Materials Science
- Nanotechnology
Background:
- The existence of the hexagonally close-packed spherical phase in single-component block copolymers was predicted but lacked experimental validation.
- This absence raised concerns about the fundamental principles governing block copolymer phase behavior.
Purpose of the Study:
- To experimentally realize the thermodynamically equilibrium hexagonally close-packed spherical phase in a single-component block copolymer system.
- To demonstrate a method for regulating block copolymer phase behavior by manipulating molecular symmetry.
Main Methods:
- Design and synthesis of discrete A1BA2 triblock copolymers using an iterative growth method.
- Precise control over chemical composition and uniform chain length to eliminate defects.
- Tuning the relative chain lengths of the end A blocks to control nanostructure formation.
Main Results:
- Fabrication of diverse ordered nanostructures, including Frank-Kasper A15 and sigma phases, by adjusting A-block lengths.
- Successful experimental access to the hexagonally close-packed spherical phase.
- Demonstration that synergistic effects of end blocks stabilize the spherical phase and relieve packing frustration.
Conclusions:
- The study provides the first experimental evidence for the hexagonally close-packed spherical phase in single-component block copolymers.
- Breaking molecular symmetry offers a robust strategy for controlling block copolymer phase behavior and accessing complex nanostructures.
- This work fills a gap in the block copolymer phase diagram and enables rational structural engineering.
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