White-Light-Mediated Imidazole Catalysis Toward Terpene-Based Thermosets

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Traditional light-curing of terpene polymers relies on UV irradiation and photoinitiators.
• Developing sustainable alternatives for polymer curing is crucial for reducing environmental impact.

Purpose of the Study:

• To investigate white light-mediated curing of terpene-derived diepoxides using imidazole catalysis.
• To explore a novel, photoinitiator-free pathway for creating bio-based thermosets.

Main Methods:

• Utilized limonene- and carvone-derived diepoxides cured with glutaric anhydride under white light.
• Employed imidazole-mediated catalysis, avoiding conventional photoinitiators.
• Characterized the curing mechanism and material properties using ¹H NMR and thermomechanical analysis.

Main Results:

• Achieved successful curing of bio-based thermosets under white light without photoinitiators.
• ¹H NMR demonstrated a light-responsive pathway with preferential endo-epoxide activation under white light, distinct from thermal curing.
• The resulting thermosets are colorless, transparent, and exhibit enhanced thermomechanical properties (Tg: 110°C, tensile strength: 42 MPa, strain at break: 15%).

Conclusions:

• A novel, environmentally friendly strategy for producing terpene-based thermosets via white light curing has been established.
• This imidazole-catalyzed approach offers a distinct light-responsive mechanism, leading to superior material properties compared to thermal curing.
• The findings broaden the scope of terpene-derived epoxy-anhydride systems and sustainable thermoset development.