Interfacial Engineering of Block Copolymer Nanostructures: Morphology and Solvent Stability

Area of Science:

• Polymer Science
• Materials Science
• Nanotechnology

Background:

• Interfacial engineering is key to controlling self-assembled nanostructures of block copolymers (BCPs).
• Solvent exchange is a critical process for BCP nanostructure formation.
• Polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) is a versatile BCP system.

Purpose of the Study:

• To demonstrate the generation of different stacked lamellae nanostructures of PS-b-P2VP.
• To investigate the effect of phosphotungstic acid (PTA) and NaCl on BCP self-assembly.
• To explore how structural changes influence particle properties and stability.

Main Methods:

• Utilized solvent exchange with PTA or PTA/NaCl aqueous solutions as nonsolvents.
• Analyzed the impact of PTA and NaCl on microphase separation and interfacial tension.
• Characterized the morphology of assembled BCP nanostructures (ellipsoidal BP and disk-like BPN).

Main Results:

• PTA participation increased P2VP volume fraction and decreased oil/water interfacial tension.
• NaCl addition further enhanced P2VP/PTA surface coverage on droplets.
• Ellipsoidal BP particles formed with PTA, while BPN disks formed with PTA/NaCl.

Conclusions:

• The study successfully generated distinct PS-b-P2VP nanostructures (BP and BPN) via interfacial engineering.
• BP and BPN particles exhibited different stabilities and dissociation conditions.
• Structural variations significantly affected the stability of loaded cargo, highlighting the importance of subtle structural control.