Singular dynamics in the failure of soft adhesive contacts

Area of Science:

• Soft matter physics
• Materials science
• Polymer mechanics

Background:

• Understanding the mechanical behavior of soft gels is crucial for applications in biomaterials and soft robotics.
• Adhesive contact failure in compliant materials can lead to complex recovery dynamics.
• Gels possess both solid (elastic network) and liquid (solvent) phases, influencing their overall mechanics.

Purpose of the Study:

• To characterize the mechanical recovery of compliant silicone gels after adhesive contact failure.
• To investigate the dynamics of gel recoil following large deformation and detachment.
• To elucidate the role of surface stress and viscous flow in the recovery process.

Main Methods:

• Establishing stable adhesive contacts between rigid microspheres and silicone gels.
• Quasi-statically stretching gels to large deformations to induce contact failure.
• Analyzing the self-similar surface profile evolution during gel recoil using a power-law relationship.
• Modeling the recovery dynamics considering both elastic and viscous properties.

Main Results:

• Adhesive contact failure was initiated and followed by gel sliding.
• Immediately after detachment, gels exhibited rapid recoil with a self-similar surface profile.
• The recoil dynamics followed a power law in time, indicating a singular detachment point.
• Observed dynamics align with a relaxation process driven by surface stress and hindered by viscous flow.

Conclusions:

• The mechanical recovery of silicone gels after adhesive failure is governed by singular dynamics.
• Both the elastic network and the liquid phase of the gel are critical for understanding its mechanics under extreme deformation.
• The findings highlight the importance of considering the poroelastic nature of gels in predicting their behavior.