Synergistic reinforcement of poly(vinyl alcohol) nanocomposites with cellulose nanocrystal-stabilized graphene

Cellulose nanocrystal-stabilized graphene (GR-CNC) was produced by liquid phase exfoliation of graphite assisted by cellulose nanocrystals (CNC), a recently reported method that allows stabilization of resulting graphene flakes in aqueous dispersions. Using a simple and environmentally friendly process, GR-CNC was incorporated into poly(vinyl alcohol) (PVA) aqueous solutions to obtain PVA-based nanocomposites (GR-CNC/PVA) by a casting method. For comparison purposes, two reference materials were also prepared following the same procedure: CNC/PVA and GR-T/PVA, where graphene was stabilized by an organic surfactant, Triton X-100 (T). At 1wt% nanofiller loading, GR-CNC/PVA exhibited superior mechanical properties (improvements in tensile strength and Young's modulus were about 20% and 50%, respectively, compared with neat PVA) than CNC/PVA (4% increase in tensile strength and 19% in Young's modulus) and GR-T/PVA (where a decrease in mechanical properties was observed), suggesting the synergistic reinforcing effect of CNC and graphene (GR). This significant reinforcement found for GR-CNC/PVA is attributed to the strong interaction between PVA and GR-CNC.