Ultralight porous poly (vinylidene fluoride)-graphene nanocomposites with compressive sensing properties

Compressible sensors with highly porous features are ideal candidates for sports and wearable electronics. This study demonstrated for the first time, how the crystalline transformation of poly (vinylidene fluoride) (PVDF) influences aerogel formation and also the compressible sensing properties of a graphene composite. In the present study, two feasible synthesis methods are demonstrated for the fabrication of both PVDF/graphene foams and aerogels with high sensitivity. A three-dimensional network of the PVDF/graphene foams and aerogels is prepared by gelation induced crystallization of PVDF/cyclohexanone by adjusting temperature and time. Herein, PVDF/graphene foams and aerogels with density range of 0.11 - 0.17 g·cm^-3 were fabricated. The compressive behaviour of PVDF/graphene aerogels was compared with PVDF/graphene foam samples. Incorporation of 20 wt.% graphene in PVDF aerogel improved the compressive strength significantly by 12 times. The electromechanical performance of foams and aerogels shows that the PVDF/20G (G represents graphene) foam sample has high sensitivity of 396.7 kPa^-1 to the pressure higher than 400 kPa, while PVDF/40G aerogels have a sensitivity value of 3.0 × 10^-3 kPa^-1 in pressure range lower than 500 kPa. The results provide new pathways to fabricate porous composite with lighter density with high mechanical and electrical properties.