Mechanism of Charge Transport in Polypyrrole–Heparin Composites

Abstract

Polypyrrole–heparin composites have been prepared by an electrochemical polymerization technique. The mechanism of charge transport in the composite has been investigated. DC conductivity has been measured in the temperature range 13–300 K. In the very low temperature regime, i.e., below 68 K, the conductivity of the composite saturates. This behavior has been attributed to the tunneling mechanism. Above 68 K, the variation of dc conductivity with temperature has been attributed to Mott's variable range hopping (VRH) mechanism. Various Mott's parameters associated with the mechanism of charge transport such as, characteristic temperature (T 0), average hopping distance (R), average hopping energy (W), and density of states at the Fermi level [N(E F)] have been evaluated in this regime and are in good agreement with the values reported earlier for other conjugated polymers.