A Self-Healable High Glass Transition Temperature Bioepoxy Material Based on Vitrimer Chemistry

Abstract

The design of high glass transition temperature (T g ) thermoset materials with considerable reparability is a challenge. In this study, a novel biobased triepoxy (TEP) is synthesized and cured with an anhydride monomer in the presence of zinc catalyst. The cured TEP exhibits a high T g (187 °C) and comparable strength and modulus to the cured bisphenol A epoxy. By adopting the vitrimer chemistry, the cross-linked polymer materials are imparted significant stress relaxation and reparability via dynamic transesterification. It is noted that the reparability is closely related to the repairing temperature, external force, catalyst content, and the magnitude of rubbery modulus of the sample. The width of the crack from the cured TEP can be efficiently repaired within 10 min. This work introduces the first high-T g biobased epoxy material with excellent reparability and provides a valuable method for the design of high-T g self-healing materials suitable for high service temperature.

A Review on the Potential and Limitations of Recyclable Thermosets for Structural Applications

“…118 To increase the circularity of these thermosets bio-based monomers can be used. Partial 126 and full 100,[127][128][129][130][131] bio-based vitrimers are already reported in recent literature.…”

Cardanol‐Based Epoxy Monomers for High Thermal Properties Thermosets

“…The lower reactivity of internal epoxies compared to terminal ones are well‐known in the literature, however, anhydrides are known to easily open these epoxy moieties . This is the reason why the epoxies were cured with 4‐methylcyclohexane‐1,2‐dicarboxylic anhydride (MHHPA), which is a common anhydride used in epoxy‐anhydride thermosets (Scheme ) . MHHPA was also chosen for its liquid state at room temperature, as it allows for a homogeneous system, whereas most anhydrides are solids at room temperature and thus the mixing process is highly complicated.…”

The Impact of Vitrimers on the Industry of the Future: Chemistry, Properties and Sustainable Forward-Looking Applications

“…Further strengthening the applicability of TE-epoxies, many attempts to implement them in advanced materials have been made. Just to mention some: silica-epoxy nanocomposites [52]; high T g self-healing bio-epoxies from vanillin-guaiacol [22] or eugenol [5]; industrial rubbers and composites thereof [56]. The major strength of transesterification is that it is targeted to commercially-relevant and straight-forward chemicals, connoting a simple implementation.…”

“…In fact, for most systems, it seems natural to assume that high temperatures and pressures up to hundreds or thousands of kPa are necessary [38]. However, when the network is extremely rigid, even 220°C for 1 h may not be enough to produce nicely welded surfaces in a hot press [22].…”