Nanocellulose Bio-Vitrimer Materials

Plastics have been used extensively in a myriad of industries due to their excellent properties, yet their use has created significant environmental challenges. Predominantly produced from depleting fossil fuel, conventional thermoplasts and thermosets are resistant to biodegradation, contributing to pollution. While thermosets dis-play exceptional mechanical properties, they cannot be recycled or remolded due to extensive crosslinked networks. Conversely, thermoplastics, which are recyclable, often lack the mechanical robustness of thermosets. In this context, vitrimers have garnered considerable attention because of their outstanding mechanical prop-erties like those of thermosets, while maintaining recyclability as thermoplastics. This is achieved by incorpo-rating dynamic covalent bonds along the polymer chain.<br/>Herein, we propose the synthesis of a distinct bio-vitrimer. In this system, we explore transesterification based dynamic covalent bonds by combining sebacic acid and epoxy modified vanillic acid. To further improve the mechanical properties of the material, different nanocellulose types (e.g. cellulose nanofibers (CNF) and cellu-lose nanocrystals (CNC)) were integrated to the synthetized vitrimer matrix. This system, based on three bio-based components, leverages the ability of the epoxy group to form covalent bonds with the two carboxylic groups of the sebacic acid and the hydroxyl groups present on the nanocellulose. Our research reveals the impact of surface modified nanocelluloses to achieve covalent adaptable networks, as well as the effect of the transesterification catalyst when reprocessing the composites.<br/>Throughout our research we investigate the recycling, thermal stability and mechanical properties of the nu-merous composites, focusing on the impact that the various bio-based materials have on those properties. We highlight the potential of recyclable bio-vitrimers to substitute currently used fossil-based polymers. Chemical modification of nanocellulose with covalent adaptable networks, offers new opportunities for the application of bio-based advanced materials in the field of adhesives, food packaging and 3D printing.