Fully bio-based cellulose nanofiber/epoxy composites with both sustainable production and selective matrix deconstruction towards infinite fiber recycling systems

Abstract

Design of nanocellulose-based composite materials suitable for selective disintegration, recovery and recycling of individual components is of great scientific and technical interest. Cellulose nanofiber/epoxy (CNF/EP) composites are candidate bio-based substitutes for petroleum-based materials. However, chemical recovery of such intimately mixed nanocomposites has not been addressed, due to the limited chemical stability of nanocellulose and due to the covalently crosslinked epoxy network. In this work we develop CNF/EP composites designed for selective disintegration. Deconstruction is achieved by including two types of labile linkages to the polymer network; acetals and esters. Besides enabling recycling of the CNF reinforcement, the thermoset constituents were further depolymerized into valuable monomeric units in 63–95% yield. In addition, the preparation of both; epoxy monomers and final composite materials is performed using solely bio-derived materials and solvents.