Vitrimeric Silicone Elastomers Enabled by Dynamic Meldrum’s Acid-Derived Cross-Links

TLDR

Vitrimer technology currently relies on a limited set of cross‑linking reactions, and new dynamic reactions can broaden its functionality and properties. The study aims to enable compression–remolding of silicone elastomers using reversible cross‑links formed by conjugate addition–elimination of thiols with a Meldrum’s acid derivative. This is achieved by reversible cross‑links generated through conjugate addition–elimination of thiols with a Meldrum’s acid derivative. After ten remolding cycles, the silicone elastomers retain their mechanical properties and stress‑relaxation activation energy, demonstrating that the Meldrum’s acid‑derived cross‑linker can be broadly applied to replace permanent thiol–ene networks and expand recyclable materials.

Abstract

Current vitrimer technology uses only a handful of distinct reactions for cross-linking. New dynamic reactions can diversify vitrimer functionality and properties. In this paper, reversible cross-links formed by conjugate addition–elimination of thiols with a Meldrum’s acid derivative enable compression–remolding of silicone elastomers. After 10 remolding cycles, there is no discernible deterioration of mechanical properties (Young’s modulus, Tg, rubbery plateau E’), nor is there a change in stress relaxation activation energy. This robust new cross-linker could be implemented in any number of systems that currently use permanent thiol–ene cross-linking, expanding the scope of recyclable materials.