posted on 2021-01-12, 04:13authored byAristotelis
P. Sgouros, Charalampos Androulidakis, Georgia Tsoukleri, George Kalosakas, Nikos Delikoukos, Stefano Signetti, Nicola M. Pugno, John Parthenios, Costas Galiotis, Konstantinos Papagelis
We
report that few graphene flakes embedded into polymer matrices
can be mechanically stretched to relatively large deformation (>1%)
in an efficient way by adopting a particular ladder-like morphology
consisting of consecutive mono-, bi-, tri-, and four-layer graphene
units. In this type of flake architecture, all of the layers adhere
to the surrounding polymer inducing similar deformation on the individual
graphene layers, preventing interlayer sliding and optimizing the
strain transfer efficiency. We have exploited Raman spectroscopy to
quantify this effect from a mechanical standpoint. The finite element
method and molecular dynamics simulations have been used to interpret
the above experimental findings. The results suggest that a step pyramid-like
architecture of a flake can be ideal for efficient loading of layered
materials embedded into a polymer and that there are two prevailing
mechanisms that govern axial stress transfer, namely, interfacial
shear transfer and axial transmission through the ends. This concept
can be easily applied to other two-dimensional materials and related
van der Waals heterostructures fabricated either by mechanical exfoliation
or chemical vapor deposition by appropriate patterning. This work
opens new perspectives in numerous applications, including high volume
fraction composites, flexible electronics, and straintronic devices.