Biobased Elastomeric Vitrimer via Imine and Acetal Metathesis Reactions

Abstract

Advancements in sustainable dynamic polymer networks remain a critical yet challenging pursuit in polymer science, despite the extensive industrial relevance of these materials. Conventional elastomeric compounds often conflict with core principles of green chemistry, as they are typically derived from petroleum-based elastomers having toxic additives and irreversible cross-linked structures that limit recyclability and reusability. This study employed epoxidised natural rubber (ENR), a biobased elastomer, to design a dual dynamic network utilizing imine and acetal metathesis chemistries. For this, initially the biobased protocatechualdehyde (3,4-dihydroxybenzaldehyde, DHB) was reacted with para-phenylenediamine (PPD) to form a Schiff’s base (DHB–PPD). Functionalization of ENR with DHB–PPD introduced dynamic imine bonds and catechol functionalities into the modified bioelastomer. Subsequently, the catechol groups were further cross-linked with 1,4-benzene dicarboxaldehyde via dynamic acetal linkages, yielding a recyclable and reprocessable vitrimeric bio- elastomer in which bioderived cross-linker was used. The combined presence of imine and acetal bonds imparted rapid stress relaxation at elevated temperatures, enabling recyclability and efficient reprocessability. Additionally, the material exhibited acid and heat triggered chemical degradability and demonstrated an excellent self-healing efficiency of 89%. These findings present a strategy for designing a self-healable and chemically recyclable elastomeric network by harnessing bioderived components and dynamic covalent chemistry based on imine and acetal metathesis reactions.