460522 Layered and Scrolled Nanocomposites with Aligned Semi-Infinite Graphene Inclusions at the Platelet Limit

Wednesday, November 16, 2016: 1:42 PM
Golden Gate 4 (Hilton San Francisco Union Square)
Pingwei Liu1, Zhong Jin2, Georgios Katsukis2, Lee Drahushuk2, Steven Shimizu2, Chih-Jen Shih2, Eric D. Wetzel3, Joshua Taggart-Scarff3, Bo Qing4, Krystyn J. Van Vliet5, Richard Li6, Brian Wardle6 and Michael Strano2, (1)Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, (2)Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, (3)Composite and Hybrid Materials Branch, U.S. Army Research Laboratory, Aberdeen Proving Grounds, MD, (4)Biological engineering, Massachusetts Institute of Technology, Cambridge, MA, (5)Materials Science and Engineering, MIT, Cambridge, MA, (6)Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA

Graphene and other two-dimensional (2D) materials are distinct among nanoscale inclusions or fillers for composites in that they can potentially span the physical dimensions of the enclosing solid. However, alignment and assembly of continuous 2D components at high volume fraction and macroscopic dimensions remains an unsolved challenge in material science. Herein, we introduce a stacking and folding method that generates layer numbers that scale as 4j where j is the number of successive quadrant segmentations of a 2D inclusion, to generate aligned graphene/polycarbonate composites with as many as 320 parallel layers spanning 0.032 to 0.11 mm thickness. An analogous transverse shear scrolling method generates Archimedean spiral nanocomposite fibers 0.10-0.16 mm in diameter and 2 cm in length. The process significantly increases the effective elastic modulus approximately 1.9-fold to nearly 1 GPa, approaching the limit of platelet filler theory, and increases the ultimate tensile strength to 40 MPa even at exceptionally low graphene volume fraction of only 0.00185. Graphene spiral fibers demonstrate exotic, telescoping elongation at break of 110%, or 30 times greater than Kevlar. Both composite types retain anisotropic electrical conduction along the graphene planar axis with a percolation threshold VG < 0.003 vol%, and layer numbers less than 36 remain transparent with optical density < 42%. These results highlight new combinations of material properties available at this extreme platelet filler limit for nanocomposites.

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