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 ( C=O) in GOn surface and fluorine group ( CF2) 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 beta-polymorph at only 0.1 wt.% GOn content. Below that content a mixture of beta and alpha-polymorph is observed. The Young's 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. (C) 2012 Elsevier B.V. All rights reserved.