Surface Reconstruction in Hydrated Amphiphilic Block Copolymer Thin Films Probed by Fluid Cell Atomic Force...

Area of Science:

• Materials Science
• Polymer Science
• Surface Science

Background:

• Interfacial energies significantly influence thin film morphology and rearrangement.
• Amphiphilic block copolymers (BCPs) offer tunable properties for surface engineering.
• Understanding solvent-induced surface reconstruction is crucial for advanced material applications.

Purpose of the Study:

• To investigate solvent-driven surface reconstructions in amphiphilic block copolymer thin films.
• To analyze the impact of polymer-solvent interactions on surface morphology and film behavior.
• To explore the role of interfacial energies in driving BCP thin film reconfigurations.

Main Methods:

• Utilized ex situ and in situ fluid cell Atomic Force Microscopy (fc-AFM).
• Employed Amplitude Modulation AFM (AM-AFM) and Amplitude-Phase Distance (APD) force spectroscopy.
• Estimated energetic driving forces using harmonic mean approximations of interfacial energies.

Main Results:

• Observed distinct differences in surface morphology and swelling between PS-b-PEO and PS-b-P-[AGE-co-EO] films.
• Revealed surface layer stratification and chain rearrangement under minimal tip-sample stimulation.
• Demonstrated that elimination of unfavorable polystyrene-water interfaces drives hydrophilic block rearrangement.

Conclusions:

• Solvent exposure induces significant surface reconstructions in BCP thin films.
• Incorporating random blocks into BCPs can increase film heterogeneity and drive morphological changes.
• These findings have implications for tuning the hydrophilicity and functionality of BCP thin films for various applications.