From vineyards to reshapable materials: α-CF2 activation in 100% resveratrol-based catalyst-free vitrimers

Abstract

Vitrimers are a class of polymers bridging the gap between resistant crosslinked thermosets and recyclable linear thermoplastics. The first vitrimer ever described was a polyester network requiring relatively high catalyst loadings to be reshaped. This feature raises concerns about catalysts potentially leaching out of the materials and accelerated ageing upon reprocessing cycles. Recently, strategies such as activation of the exchange reaction by inductive effects or neighboring group participation have been implemented in vitrimers allowing the production of reshapable materials which do not require a catalyst. Hence, α,α-difluoro esters proved to be very prone to transesterification owing to the strong electron-withdrawing character of the CF₂ group resulting from the very high electronegativity of fluorine. This feature implemented in polyester vitrimers enabled the synthesis of catalyst-free reshapable highly crosslinked networks. Moreover, this principle initially designed for petro-based monomers is here successfully adapted for resveratrol, a biobased polyphenol found in high concentrations in grapes and Japanese knotweed (Reynoutria japonica). The material presented contains 86% bio-based carbon, is catalyst-free, durable and recyclable, and features a high T_g.