Adhesion in hydrogel contacts

Area of Science:

• Materials Science
• Polymer Physics
• Chemical Engineering

Background:

• Hydrogels are crucial in various applications, but their adhesion mechanisms, especially energy dissipation, are complex.
• Understanding dissipation is key to controlling hydrogel behavior in contact and detachment scenarios.

Purpose of the Study:

• To develop a generalized thermomechanical model for hydrogel adhesion.
• To elucidate the mechanisms of energy dissipation within the viscoelastic bulk of hyperelastic hydrogels.
• To identify factors influencing adhesion dynamics and propose a parameter for dominant dissipation mechanism discernment.

Main Methods:

• Development of a generalized thermomechanical model.
• Analysis of energy dissipation, including interface formation, viscous flow, and bulk composition effects.
• Investigation of phase inhomogeneity and morphological changes within the hydrogel bulk.
• Incorporation of mixing thermodynamics to understand phase dynamics.
• Inclusion of time-dependent behavior in the model.

Main Results:

• The model identified three primary dissipation mechanisms: interface formation, viscous flow, and bulk composition changes due to phase inhomogeneities.
• Phase inhomogeneity dynamics, governed by mixing thermodynamics, can either enhance or disrupt adhesion.
• The model successfully accounts for the time-dependent nature of hydrogel adhesion and detachment.
• A novel parameter was proposed to distinguish the dominant dissipation mechanism during hydrogel contact detachment.

Conclusions:

• Hydrogel adhesion dissipation is a complex interplay of interface, viscous, and bulk phenomena.
• Bulk composition and morphology, driven by thermodynamics, play a critical role in adhesion.
• The developed model provides a framework for understanding and predicting hydrogel adhesion behavior.
• The proposed parameter aids in characterizing hydrogel detachment mechanisms.