Piezoelectric β-polymorph formation and properties enhancement in graphene oxide – PVDF nanocomposite films

Graphene oxide nanosheets (GOn)/PVDF nanocomposite films were prepared by solution casting method with various GOn contents. GOn were obtained via sonication of bulk graphite oxide in dimethylformamide (DMF). Due to the strong and specific interaction between carbonyl group (2 bonds on the lefthand sideCdouble bond; length as m-dashO) in GOn surface and fluorine group (2 bonds on the lefthand sideCF2) in PVDF, the GOn were homogeneously dispersed and distributed within the matrix. The chosen approach for preparation and the high compatibility between GOn and PVDF result in the formation of purely piezoelectric β-polymorph at only 0.1 wt.% GOn content. Below that content a mixture of β and α-polymorph is observed. The Youngʹs modulus and tensile strength of PVDF were respectively increased by 192% and 92% with the addition of 2 wt.% GOn. The thermal stability of PVDF polymer was also significantly increased with increasing of GOn loading. The as-obtained flexible nanocomposite films with such low GOn content can be used as active materials in the field of piezoelectric applications.