Tailoring fully biobased optical adhesives via hydrogen-bonding modulation

Area of Science:

• Materials Science
• Polymer Chemistry
• Optoelectronics

Background:

• Optical adhesives are crucial for display technologies, demanding high optical clarity, refractive index control, low birefringence, and adhesive strength.
• Current commercial adhesives often utilize petroleum-derived acrylates and isocyanate-based urethanes, posing environmental concerns.
• There is a need for sustainable alternatives that meet stringent optical and mechanical performance requirements.

Purpose of the Study:

• To develop a fully biobased optical adhesive.
• To explore the use of initiator-free photopolymerization of dithiolanes for adhesive formulation.
• To demonstrate the tunability of adhesive properties through chemical modification.

Main Methods:

• Synthesis of biobased dithiolane monomers conjugated to macromolecular cores.
• Initiator-free photopolymerization technique for crosslinking the dithiolane-based adhesives.
• Characterization of optical properties (transmittance, haze, dispersion) and physical properties (glass transition temperature, adhesion).

Main Results:

• A fully biobased optical adhesive was successfully formulated using initiator-free dithiolane photopolymerization.
• Adhesive properties, including glass transition temperature and refractive index, were effectively modulated by altering the dithiolane conjugation chemistry.
• The developed adhesives exhibited excellent optical performance: >98% visible light transmittance, <0.7% haze, and low optical dispersion.

Conclusions:

• Dithiolanes serve as effective initiator-free crosslinkers for creating fully biobased optical adhesives.
• The presented approach allows for precise control over adhesive properties, meeting the demands of advanced display applications.
• This work offers a sustainable pathway for high-performance optical adhesives, reducing reliance on petroleum-based materials.