Novel PTFE Nanocomposites Reinforced with Artificially Stacked Hybrid Graphene/h-BN Nanostructures

Novel PTFE Nanocomposites Reinforced with Artificially Stacked Hybrid Graphene/h-BN Nanostructures

Sai Aditya Pradeep^1,2, AB Kousaalya¹, Srikanth Pilla^1,2*

¹Department of Automotive Engineering, Clemson University, Greenville, SC, USA

²Department of Materials Science and Engineering, Clemson University, Clemson, SC, USA

^*spilla@clemson.edu; Tel: 1-864-283-7216

The invention of Graphene has attracted widespread attention towards next generation two dimensional (2D) meta materials such as h-BN, MoS₂, and WS₂. A hallmark of 2D materials is their strong covalent in-plane bonding and weak van der Waals like coupling between layers, which enables us to tune their bandgap. Among all 2D materials, graphene and h-BN have the distinction of possessing nearly identical honeycomb structure and lattice thickness that forms the theoretical basis of constructing these 2D stacked layers. The exfoliation of 2D layers from a 3D bulk material is a process ranging from nano to meso scale due to effects like bubble cavitation, intercalation and disruptive fragmentation. Chemical exfoliation provides an effective means of isolating and manipulating individual layers thereby tuning the bandgap. In this work, individual layers of graphene and h-BN are exfoliated in aqueous and organic media via ultrasonication. The exfoliated graphene and h-BN were then mixed together to obtain artificially stacked layers using solution self-assembly process. The exfoliated and stacked layers are then impregnated into Polytetrafluoroethylene (PTFE) via solution casting to obtain novel hybrid-layered nanocomposites. Extent of exfoliation, stacking sequence, number of stacked layers, and atomic mismatch between stacked layers are characterized using Transmission electron microscopy and Raman spectroscopy. Variations in band gap, as a function of stacking sequence, are characterized using UV-visible spectroscopy. The ratio of Graphene/h-BN in the stacked solid is ascertained by thermogravimetric analysis (TGA). Surface morphology and dispersibiltiy of the exfoliated layers in the cast films is characterized using Scanning electron microscopy.