Green chemistry: Co-assembly of tannin-assisted exfoliated low-defect graphene and epoxy natural rubber latex to form soft and elastic nacre-like film with good electrical conductivity

In this paper, we successfully prepared low-defect exfoliated graphene-based soft nacre-like composite film with superb elasticity and electrical conductivities, which is quite different from the conventional graphene oxide based film. Herein, we demonstrate a large-scale exfoliation process of graphite by incorporation of Myrtan Condensed Tannins (MCT), a natural polyphenol product extracted from bark of Arbutus. MCT could successfully produce large quantities of exfoliated graphene suspension (2.33 mg mL−1) with very few defects (ID/IG ∼ 0.27) in water, where more than 68% of these flakes are monolayer. Furthermore, via vacuum-assisted layer-by-layer self-assembled method, the soft and elastic exfoliated graphene-based nacre-like composite film was prepared using epoxy natural rubber (ENR) latex as crosslinking agent. Flexibility and stability of this graphene-based electrical conductive film are greatly enhanced at the same time. The composite films could be stretched by 20% of its initial length with 54 wt % of ENR in it and it could also be directly used as a conductive wire for an LED lamp with a conductivity of 157 S m−1. Most importantly, most of the raw materials used in this work are low cost natural products which is environmental-friendly and also suitable for production in large quantities.

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