Elastomeric Nanocomposite with Solvent-Free, One Step, In Situ Shear Exfoliation of Graphite to Graphene

A graphene nanoflake (GNF)-enhanced elastomeric nanocomposite (G-EMC) is fabricated following an innovative, cost-effective, single-step, in situ shear exfoliation (ISE) method from low-cost bulk material, graphite, where uniform mixing happens simultaneously within the elastomer matrix. Electron microscopy, atomic force microscopy, and photo-induced force microscopy results show good dispersion of GNFs with exfoliation to a few layers and uniform distribution in the elastomer matrix. X-ray photoelectron spectroscopy analysis shows less than 1% oxygen-containing functional groups/impurity, enhanced bonding through the formation of edge sites as fracture occurs across the GNF basal plane, and pi-pi interactions with newly exfoliated planar basal plane surfaces of the GNFs. Raman spectroscopy results confirm the formation of GNFs with only a few layers of graphene formed by the ISE process. Fabricated 10 wt.% G-EMC nanocomposites show a 400%–500% increase in strength and fracture toughness. And 35 wt.% G-EMCs provide an electrical conductivity of 25.64 S m⁻¹ and a sensor gauge factor of 45. The resulting intrinsic piezo resistivity of the fabricated nanocomposite has been exploited to fabricate a multi-functional wired and wireless sensor for detecting different body movements, speech, human vital functions, solvents, and biomolecules.