  The biaxial mechanical properties constitute another remarkable advantage of
graphene, but their evaluation has been overlooked in polymer nanocomposites.
Herein, we provided an innovative and practical method to characterise biaxial
reinforcement from graphene via swelling of elastomers, where graphene
nanoplatelets were controlled to be oriented in-plane. The in-plane-aligned
graphene imposed a biaxial constraining force to the elastomer during the
swelling process that led to the anisotropic swelling behaviour of the bulk
nanocomposites.
