A Photocured Bio-based Shape Memory Thermoplastics for Reversible Wet Adhesion

Area of Science:

• Materials Science
• Polymer Chemistry
• Adhesion Science

Background:

• Developing reversible wet or underwater adhesives is challenging due to water's interference with intermolecular interactions and reduced contact area.
• Existing adhesives often fail in wet environments, limiting their application in marine or biomedical fields.

Purpose of the Study:

• To develop a novel photocured, bio-based shape memory polymer (SMP) capable of strong chemical and structural adhesion to wet surfaces.
• To investigate the adhesion mechanism and performance of the SMP under various conditions, including long-term underwater exposure.

Main Methods:

• Polymerization of three bio-sourced monomers to create linear polymer chains with hydrophobic side chains.
• Utilizing hydrogen bonding for surface interaction and hydrophobic chains for protection.
• Tuning the glass transition temperature (Tg) between 17-38 °C for reversible adhesion.
• Demonstrating applications in leak repair and underwater on-skin sensors.

Main Results:

• The SMP exhibited tunable phase transition temperature (Tg) from 17-38 °C.
• Above Tg, the adhesive conformed to surfaces; below Tg, it locked into a glassy state, increasing contact area.
• Achieved long-term underwater adhesion exceeding 15 days with a maximum strength of approximately 0.9 MPa.
• Successfully demonstrated applications in leak repair and underwater on-skin sensors.

Conclusions:

• The developed bio-based SMP offers a robust solution for reversible wet and underwater adhesion.
• The strategy of combining chemical bonding, shape memory effect, and hydrophobic protection is effective for enhancing adhesion.
• This approach provides a general pathway for designing sustainable, long-lasting adhesives from renewable resources for diverse applications.