Engineering sticky superomniphobic surfaces on transparent and flexible PDMS substrate.

Area of Science:

• Materials Science and Engineering
• Surface Chemistry
• Nanotechnology

Background:

• Superhydrophobicity prevents water adhesion, while superomniphobicity extends repellency to diverse liquids like oils and solvents.
• Theoretical models guide the design of microstructured surfaces for achieving superomniphobicity on rigid substrates like silicon.

Purpose of the Study:

• To transfer superomniphobic technology from rigid silicon to flexible polydimethylsiloxane (PDMS) substrates.
• To create 'sticky superomniphobic' surfaces with high contact angles and hysteresis.
• To validate a modified Cassie wetting model for droplet behavior on these novel surfaces.

Main Methods:

• Fabrication of superomniphobic surfaces on silicon using theoretical design criteria.
• Replication of microstructured surfaces onto flexible PDMS using a molding process.
• Surface chemical modification of PDMS to achieve superomniphobicity.
• Experimental characterization of droplet behavior, including apparent contact angles and contact angle hysteresis.
• Application of a modified Cassie equation to analyze wetting phenomena.

Main Results:

• Successfully created flexible sticky superomniphobic surfaces on PDMS substrates.
• Achieved large apparent contact angles (>150°) and significant contact angle hysteresis (>10°) for various liquids.
• Experimental data showed good agreement with the modified Cassie equation, confirming its validity for 1D wetting analysis.

Conclusions:

• The study demonstrates a viable method for producing flexible superomniphobic surfaces.
• The developed surfaces exhibit robust liquid repellency, applicable to a wide range of liquids.
• The modified Cassie equation effectively describes droplet behavior on these engineered surfaces.