Photoinduced microphase separation in block copolymers: exploring shape incompatibility of mesogenic side groups

Area of Science:

• Polymer Science
• Materials Chemistry
• Nanotechnology

Background:

• Block copolymers (BCP) self-assemble into various nanostructures.
• Controlling BCP morphology typically requires complex processing techniques like lithography.
• Liquid crystalline polymers (LCP) offer unique responsive properties.

Purpose of the Study:

• To achieve photoinduced microphase separation in block copolymers.
• To utilize side-chain liquid crystalline polymers (SCLCP) for light-directed self-assembly.
• To explore a lithography-free method for organizing BCP morphology.

Main Methods:

• Synthesized a diblock copolymer of two SCLCPs with miscible mesogenic side groups.
• Utilized UV irradiation to induce trans-cis isomerization of azobenzene mesogens in one block.
• Observed the resulting microphase separated morphology.

Main Results:

• Successfully induced microphase separation in the SCLCP diblock copolymer using light.
• Trans-cis isomerization of azobenzene mesogens led to shape incompatibility.
• This incompatibility drove the separation of the polymer blocks, forming distinct microdomains.
• Achieved a well-defined microphase separated morphology via photoisomerization.

Conclusions:

• Photoinduced microphase separation is a viable strategy for BCP morphology control.
• Light can be used as a tool to process and organize polymer nanostructures.
• This approach offers a promising lithography-free route for fabricating nanostructured materials.