Glycerol Induced Catalyst‐Free Curing of Epoxy and Vitrimer Preparation

Abstract

Epoxy vitrimers prepared from anhydride‐cured epoxies exhibit, repairable and reprocessable properties; however, they generally rely on a large amount of catalyst for accelerating the dynamic transesterification (DTER). If the catalyst loading is not enough, the vitrimer properties will be limited. In this work, a preparation method of catalyst‐free epoxy vitrimer is demonstrated by adding glycerol to an epoxy–anhydride curing system. The hydroxyls of glycerol first react with the anhydride to induce the ring‐opening of anhydride and form a carboxylic acid, and the latter attacks the epoxy and form a β‐hydroxyester linkage, so the curing can be performed in the absence of catalyst. A significant amount of hydroxy groups are preserved in the crosslinked network, and they serve as both reacting moiety and catalyst for the DTER, which imparts fast relaxation and satisfactory repairability to the materials. By taking advantage of this mechanism, a catalyst‐free and self‐healing coating is demonstrated. These findings provide a solution to avoid using catalyst in vitrimer preparation and advance the application of vitrimer in coating. However, the addition of glycerol produces a decrease of the T g of the final materials, which needs to be further addressed in the future study.

Carbon Fiber Reinforced Epoxy Vitrimer: Robust Mechanical Performance and Facile Hydrothermal Decomposition in Pure Water

“…[ 4,5 ] In another study, a polyhydric compound, that is, glycerol, was added directly to the epoxy‐anhydride curing system to prepare a vitrimer material. [ 6 ] No external catalyst was needed in either case, because the abundant OHs acted as internally catalytic species to promote both the curing reaction (Scheme S1, Supporting Information) and the DTER in the resulting vitrimer. In addition, we also demonstrated that excellent self‐catalysis of vitrimer preparation were achievable by employing glycidylamine type epoxies and triethanolamine as an polyhydric compound.…”

“…E a was calculated as 85.9 kJ mol −1 which was comparable to that of the epoxy vitirmers reported in literatures. [ 2,6 ] In considering the fast relaxation rate, moderate T g , low viscosity of the prepolymer, E N.17 ‐GA was used in the subsequent composite preparation.…”

Recyclable High-Performance Epoxy-Anhydride Resins with DMP-30 as the Catalyst of Transesterification Reactions

“…High catalyst loading may lead to the aggregation and leaching of catalysts, resulting in a decrease in the material performance [16,46]. Secondly, these catalysts are toxic and corrosive, which may cause corrosion damage to materials [47]. Thirdly, these catalysts are prone to oxidation failure at elevated temperatures and difficult to separate from the dissolution mixture, which limits the recycling of catalysts for reuse [41,48].…”

Implantation of Recyclability and Healability into Cross-Linked Commercial Polymers by Applying the Vitrimer Concept

“…Subsequently, using three different trans-estefication catalysts (i.e., Zn(OAc) 2 , TBD, and triphenylphosphine (PPh 3 )), they demonstrated control over the vitrimeric properties [ 24 ]. In addition, recently, trans-esterification-based polyester vitrimers have been found to be operated without adding bond exchange catalysts, by incorporating abundant free OH groups that served as both reacting moieties and catalysts [ 48 , 49 , 50 ]. As an example, Figure 9 b represents the molecular design reported by Guo and Zhang et al [ 48 ].…”