Electrical properties of intrinsically conductive core-shell polypyrrole/poly(vinylidene fluoride) electrospun fibers
Polypyrrole (PPy) has been synthesized as an homogeneous layer on the fibers of electroactive poly(vinylidene fluoride) (PVDF) electrospun mats via in-situ polymerization of pyrrole (Py). A core-sheath structure was obtained, the electrical conductivity depending on synthesis time, which influences the morphology and thickness of PPy layer. An overall dc conductivity of 70 ± 4 S m-1 was obtained for the sample with a PPy layer of 160 ± 25 nm. Further, the thermal coefficient of resistivity obtained for the sample after 120 min in-situ polymerization is almost twice the one calculated for the sample with 5 min synthesis time. The temperature dependence of the electrical dc conductivity of the PPy/PVDF membranes gives evidence of a transport mechanism based on Mott's variable range hopping model. Using this model, values for the density of states, hopping energy and distance were assessed.