Design of High-Performance, Robust, and Recyclable Epoxy Resins

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Chemistry

Background:

• Epoxy resins (ERs) are widely used but suffer from poor recyclability, a significant sustainability challenge.
• Current methods for reprocessable ERs often involve complex monomer synthesis and result in inferior mechanical properties.

Purpose of the Study:

• To develop a straightforward strategy for synthesizing robust, fully reprocessable epoxy resins.
• To investigate the use of dynamic thioether linkages formed in-situ via thiol-epoxy click reactions.

Main Methods:

• Utilized thiol-epoxy "click" reactions to achieve in-situ generation of dynamic thioether linkages.
• Characterized the thermal stability, mechanical properties (storage modulus, Tg), and creep resistance of the synthesized ERs.
• Evaluated shape-memory effects, adhesion to metal substrates, and degradability.

Main Results:

• Achieved ERs with thermal stability and mechanical properties comparable to commercial ERs.
• Demonstrated tunable properties (Tg, modulus, relaxation dynamics) by controlling cross-link density.
• Exhibited superior creep resistance up to 120 °C, reversible dual shape-memory effect, and good adhesion to aluminum and steel.
• Successfully demonstrated degradation in the presence of excess thiol.

Conclusions:

• This work presents the first report of dynamic thioether linkages for robust, reprocessable, and creep-resistant ERs.
• The developed ERs show promising adhesive properties and end-of-life degradability, addressing key sustainability concerns.
• The in-situ dynamic exchange mechanism simplifies synthesis compared to conventional methods.