Highly Stretchable and Adhesive Soft Vitrimers Based on N →B Coordination Structure

Abstract

Recently, vitrimers with a reversible N[Formula: see text]B coordination dynamic structure have garnered interest not only for their self-healing and reprocessable properties but also for their hydrolytic stability. Reported vitrimers with N[Formula: see text]B internal coordination dynamic structure were excessively rigid, limiting their stretchability and toughness. This study synthesized a cross-linking agent (DNCB) with a cyclic nitrogen-boron coordination structure. This agent was then used in copolymerization with n-butyl acrylate (BA) and 4-vinylphenylboronic acid (BOH) to create soft vitrimers. By systematically tuning the composition, soft vitrimers exhibit water resistance along with high viscoelasticity, stretchability, toughness, and adhesive properties against various substrates. The observed mechanical behavior is attributed to the rapid relaxation of N[Formula: see text]B coordination bonds and slow relaxation of B-O bonds in boroxine within the polymer network. It is anticipated that these soft vitrimers will be applied in adhesives, flexible electronics, and soft robotics due to their favorable properties.