Urea-Urease pH-Clock-Enabled Time-Lapse Thiol-Acrylate Adhesives: Two-Part Formulations and One-Pot Underwater...

Area of Science:

• Polymer Chemistry
• Materials Science
• Biocatalysis

Background:

• Thiol-acrylate adhesives are widely used but lack precise control over curing times.
• Existing systems often react immediately upon mixing, limiting application flexibility.
• Enzymatic reactions offer potential for controlled chemical processes.

Purpose of the Study:

• To develop time-lapse thiol-acrylate adhesive systems with programmable curing.
• To utilize a urea-urease pH-clock reaction for temporal control.
• To demonstrate applications in both two-part and one-pot formulations, including underwater curing.

Main Methods:

• Incorporated watermelon seed powder (WMSP) as a source of urease for enzymatic ammonia generation.
• Developed a two-part adhesive system with tunable induction periods via pH changes.
• Created a one-pot, water-activated formulation for shelf-stability and rapid curing upon wetting.
• Utilized thiol-Michael polymerization kinetics influenced by pH shifts.

Main Results:

• The two-part system demonstrated programmable working times with lap shear strength of 7 MPa on polycarbonate.
• The one-pot system showed shelf-stability and rapid underwater curing, achieving lap shear strengths of ~5 MPa.
• Enzymatically generated ammonia from WMSP effectively controlled the pH and polymerization rate.

Conclusions:

• WMSP-derived enzymatic catalysis provides effective temporal control in thiol-acrylate adhesives.
• Programmable curing enables new applications, including underwater adhesive formulations.
• The pH-clock reaction offers a versatile strategy for designing advanced adhesive materials.