Dynamic crosslinking towards well-dispersed cellulose nanofiber reinforced epoxy vitrimer composites

Abstract

Cellulose nanofiber (CNF) shows great potential in polymer composites but is difficult to disperse in crosslinking polymers because it tends to aggregate during static curing. Herein, we report a new approach to fabricate well-dispersed CNF reinforced epoxy composites through dynamic crosslinking combined with vitrimer chemistry. In this approach, CNF is dispersed in epoxy vtrimer by mixing with epoxy monomer, curing agent, and catalyst and subsequent dynamic crosslinking of the raw materials. The epoxy vitrimer/CNF composite fabricated by dynamic crosslinking showed better CNF dispersion compared to the counterpart prepared by static curing. No obvious aggregation of CNF occurred with the loading ≤0.75% through dynamic crosslinking. The tensile strength and Young's modulus of the epoxy vitrimer were enhanced by 2.26 and 3.61 times respectively by incorporation of 0.75 wt% CNF. We believe this facile approach could be extended to fabricate other vitrimer composites.