Density Functional Theory Approach to Interpret Elastowetting of Hydrogels.

Area of Science:

• Soft Matter Physics
• Materials Science
• Surface Science

Background:

• Sessile hydrogel drops display unique wetting behaviors.
• Understanding hydrogel-surface interactions is crucial for material design.

Purpose of the Study:

• To investigate the contact forces between hydrogels and rigid surfaces.
• To identify the role of hydrogel elasticity in surface interactions.
• To develop a theoretical model for hydrogel wetting.

Main Methods:

• Density functional theory calculations.
• Experimental observations of sessile polyacrylamide hydrogels.
• Varying hydrogel elasticity on glass surfaces.

Main Results:

• A critical hydrogel elasticity induces a switch from attractive to repulsive forces with a glass surface.
• The theoretical model accurately predicts experimental observations.
• The model reconciles with established laws (Young's law, work of adhesion) in limiting cases.

Conclusions:

• Hydrogel elasticity is a key parameter governing its interaction with rigid substrates.
• A novel theoretical framework explains hydrogel wetting and contact morphology.
• The findings offer insights into designing hydrogel-based materials with controlled surface adhesion.