Architecture Effect on Network Phase Formation from Controlled Self-Assembly of High‑χ Block Copolymers

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Block copolymers (BCPs) are versatile macromolecules with distinct blocks that self-assemble into ordered nanostructures.
• High-χ BCPs, like polystyrene-block-polydimethylsiloxane (PS-b-PDMS), exhibit strong segregation, leading to complex phase behaviors.
• Understanding the influence of molecular architecture on self-assembly is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the effect of block copolymer architecture on self-assembly.
• To explore the formation of network phases in high-χ BCPs using controlled self-assembly techniques.
• To compare the self-assembly behavior of linear diblock and star BCPs.

Main Methods:

• Synthesis of lamellae-forming diblock and star BCPs (three- and six-arm).
• Controlled self-assembly via tuning solvent evaporation rates using PS-selective solvents.
• Characterization of self-assembled morphologies.

Main Results:

• Star BCPs, unlike linear diblocks, easily form network phases through controlled self-assembly.
• A variety of network phases were achieved, including double gyroid, Frank-Kasper-like, and double diamond structures.
• Alleviation of packing frustration in star BCPs facilitates the formation of complex topological features.

Conclusions:

• BCP architecture plays a critical role in dictating self-assembled phase behavior.
• Controlled self-assembly offers facile access to diverse and complex network phases from star BCPs.
• This approach provides a pathway to engineer intricate nanostructures for advanced applications.