Adhesion between Hydrophobic Elastomer and Hydrogel through Hydrophilic Modification and Interfacial Segregation

Area of Science:

• Materials Science
• Polymer Science
• Soft Robotics

Background:

• Soft stretchable devices rely on reliable interfaces between heterogeneous materials.
• Understanding adhesion between dielectric elastomers and hydrogels is critical for device reliability.

Purpose of the Study:

• Investigate the adhesion dynamics between oxygen plasma-treated polydimethylsiloxane (PDMS) and a polyacrylamide hydrogel.
• Characterize the role of a viscous interfacial layer in adhesion and energy dissipation.

Main Methods:

• Fabrication of soft stretchable devices using extrusion printing.
• Adhesion testing of PDMS-hydrogel interfaces over time.
• Contact angle measurements to assess surface properties.
• Analysis of interfacial layer formation and its impact on debonding.

Main Results:

• Adhesion strength between treated PDMS and hydrogel increased to 15 J m⁻² over ~6 days.
• Hydrophobic recovery of plasma-treated PDMS was suppressed by the hydrogel.
• A viscous layer at the interface dissipated energy during debonding and enabled adhesion recovery.

Conclusions:

• The presence of a rheological modifier in the hydrogel and hydrophilic surface treatment of PDMS are essential for viscous layer formation.
• This viscous layer significantly enhances the robustness and self-healing capabilities of soft material interfaces.
• Findings are vital for designing reliable and durable soft electronic devices.