Design of Mixed PDMS-mPEG Slippery Covalently Attached Liquid-Like Surfaces

Area of Science:

• Materials Science
• Surface Chemistry
• Tribology

Background:

• Low droplet friction is crucial for various liquid-solid surface interactions.
• Existing surfaces often struggle to balance slipperiness with tunable wettability.

Purpose of the Study:

• To fabricate and characterize novel liquid-like surfaces with ultralow static droplet friction.
• To investigate the relationship between polymer mixture composition and surface properties like contact angle hysteresis.

Main Methods:

• A two-step spin coating process was used to create mixed layers of polydimethylsiloxane (PDMS) and methoxy polyethylene glycol (mPEG).
• Contact angle measurements were performed to determine wettability and hysteresis.
• Atomic force microscopy (AFM) was employed to analyze the surface morphology and polymer mixing.

Main Results:

• A minimum contact angle hysteresis of 0.9 ± 0.3° was achieved on hydrophilic mPEG layers, the lowest reported for covalently attached liquid surfaces.
• The contact angle hysteresis varied with PDMS fraction, reaching a maximum of 9° at 70% PDMS.
• AFM confirmed that the polymers were fully mixed on the surface, regardless of composition.

Conclusions:

• The fabricated liquid-like surfaces offer significantly reduced friction compared to conventional materials.
• These surfaces provide a tunable platform for studying interfacial phenomena and have potential applications in heat transfer, water capture, and antifouling.