  We report the scientific and technical queries regarding the article reported
by Kim et al.1 on the mechanical properties of graphene-poly(methyl
methacrylate) (PMMA) composites. Our analysis finds that the current
experimental data is insufficient to fully support the conclusions presented in
the article. We suggest the enhancement in Youngs modulus and strength of the
graphene-PMMA laminates (GPL) samples are mainly due to the heat treatment of
the polymer rather than the incorporation of graphene. The Raman spectroscopy
data (as per our analysis) for the GPL samples indicates that large cracks and
defects were introduced during the hot rolling process used to fabricate the
graphene-PMMA composite. We believe that the queries will aid the audience in
better understanding the mechanical response of graphene-PMMA composites.
