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 +/- 4S 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. (C) 2014 Elsevier B.V. All rights reserved.