Graphene-based materials with a negative Poisson’s
ratio
have numerous potential applications in various fields. However, the
modification of graphene is cumbersome and may worsen the mechanical
properties. The scale limitation and structural instabilities of suspended
graphene are also unfavorable for practical applications. In the present
study, we design several nanolayered graphene/Cu composites and investigate
their tensile behavior using molecular dynamics simulations. The nanolayered
composites exhibit an apparent auxetic behavior without any modification
of graphene, as the graphene/Cu interface can significantly enhance
the surface effect and lead to an earlier phase transformation of
the Cu component. A simultaneous occurrence of a positive and negative
Poisson’s ratio can be achieved in an asymmetric composite
due to the good blocking effect of graphene on two separated Cu films.
Materials with simultaneous negative/positive Poisson’s ratio
have potential applications in scaffold design, where it is necessary
to tune the magnitude and polarity of the Poisson’s ratio in
tissue engineering. Furthermore, we propose a composite consisting
of alternating multilayer graphene and thin Cu films to overcome the
scale limitation, whose negative Poisson’s ratio persists when
the total thickness exceeds 100 nm. It is found that the change in
the absolute value of Poisson’s ratio becomes smaller with
an increase in total thickness. Graphene/Cu composites with only a
slight deformation under external loading may be suitable for the
fabrication of telecommunication cables, whose dimensions should remain
unchanged when subjected to high hydrostatic pressure in the deep
ocean.
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