Reversibly Cross-linkable Bottlebrush Polymers as Pressure-Sensitive Adhesives

Area of Science:

• Polymer Chemistry
• Materials Science
• Adhesives Technology

Background:

• Bottlebrush polymers offer unique properties due to their architecture.
• Developing dynamically cross-linkable adhesives is crucial for advanced applications.
• Existing adhesives often lack recyclability and tunable mechanical strength.

Purpose of the Study:

• To synthesize dynamically cross-linkable bottlebrush polymer adhesives.
• To investigate the effect of cross-linking on adhesive properties.
• To demonstrate the recyclability of these novel polymer adhesives.

Main Methods:

• Grafting-from synthesis combining ring-opening metathesis polymerization (ROMP) and photoiniferter polymerization.
• Formation of disulfide cross-links via thiol oxidation.
• Characterization of mechanical properties using peel tests.
• Demonstration of recyclability via disulfide bond reduction.

Main Results:

• Well-defined bottlebrush polymers with high molar masses (>11,000 kg/mol) were synthesized.
• Un-cross-linked polymers showed cohesive failure and consistent peel strength (~30 g/mm).
• Cross-linked polymers exhibited significantly enhanced peel strength (up to sixfold increase) and a shift to adhesive failure.
• Disulfide bonds were effectively reduced, allowing for adhesive recasting with preserved properties.

Conclusions:

• The developed bottlebrush polymers serve as effective dynamically cross-linkable adhesives.
• Cross-linking via disulfide bonds significantly enhances adhesive performance.
• The reversible nature of disulfide bonds enables efficient recycling of the adhesive materials.