Metal-Catalyzed Transesterification for Healing and Assembling of Thermosets

TLDR

Bond exchange reactions controlled by catalysis enable healing of cross‑linked polymers, though at low temperatures the reactions are sluggish and the materials behave like conventional epoxy thermosets. High‑temperature healing of epoxy‑acid and epoxy‑anhydride thermosets is achieved with transesterification catalysts, with kinetics governed by the reaction rate, and varying catalyst concentration enables flexible welding and assembly not possible with thermoplastics.

Abstract

Catalytic control of bond exchange reactions enables healing of cross-linked polymer materials under a wide range of conditions. The healing capability at high temperatures is demonstrated for epoxy-acid and epoxy-anhydride thermoset networks in the presence of transesterification catalysts. At lower temperatures, the exchange reactions are very sluggish, and the materials have properties of classical epoxy thermosets. Studies of model molecules confirmed that the healing kinetics is controlled by the transesterification reaction rate. The possibility of varying the catalyst concentration brings control and flexibility of welding and assembling of epoxy thermosets that do not exist for thermoplastics.