Catalytic Control of the Vitrimer Glass Transition

TLDR

Vitrimers are covalent organic networks that undergo thermoactivated bond exchange, allowing them to flow as viscoelastic liquids at high temperatures and behave as classical thermosets at low temperatures, with the liquid–solid transition being a reversible glass transition. The study aims to tune the vitrimer glass transition temperature and its breadth by varying catalyst content and nature in epoxy‑based vitrimers. This is accomplished by adjusting the transesterification reaction rate through catalyst modification. This tunability enables practical thermoset applications such as self‑healing and processability across a broad temperature range.

Abstract

Vitrimers, strong organic glass formers, are covalent networks that are able to change their topology through thermoactivated bond exchange reactions. At high temperatures, vitrimers can flow and behave like viscoelastic liquids. At low temperatures, exchange reactions are very long and vitrimers behave like classical thermosets. The transition from the liquid to the solid is reversible and is, in fact, a glass transition. By changing the content and nature of the catalyst, we can tune the transesterification reaction rate and show that the vitrimer glass transition temperature and the broadness of the transition can be controlled at will in epoxy-based vitrimers. This opens new possibilities in practical applications of thermosets such as healing or convenient processability in a wide temperature range.