We are reporting the formation of free-standing graphene foam (GF) via a novel
two-step process, in which a polyurethane (PU) foam is first dip-coated with
graphene oxide (GO) and subsequently the dried GO-coated-PU is heated in
nitrogen atmosphere at 1000°C. During the pyrolysis of the
GO-coated-PU, GO is reduced to GF whereas PU is simultaneously decomposed and
released completely as volatiles in a step wise mass-loss mechanism. Morphology
of the formed GF conforms to that of the pure PU foam as indicated by the
scanning electronic micrographs. Polydimethylsiloxane (PDMS) was successfully
infiltrated inside the GF to form flexible and stretch-able conductors. The
GF-PDMS composite was tested for it’s pressure and strain sensing
capabilities. It is shown that a 30% compressive strain changes resistance of
the GF-PDMS composite to about 800% of it’s original value. Since
density of the formed GF is tunable, therefore, the pressure/strain sensivity of
the GF-PDMS composite is also tunable.