D.C. conductivity behaviour of poly(vinyl alcohol)-based ferrogels: role of borax and carbonyl iron

Abstract

The d.c. conductivity of poly(vinyl alcohol) hydrogels and ferrogels, cross-linked with borax, has been studied using two-probe resistance measurement method as a function of cross-linker and dopant concentrations. The availability of charge carriers (i.e. unbound borate ions and free sodium ions) in these matrices is seen to vary with cross-linker and dopant concentrations. Increase in borax concentration leads to the rise in d.c. conductivity values. Enhancement in the carbonyl iron dopant proportions, at unchanged borax concentrations, causes a decrease in the conductivity. This behaviour is explained on the basis of structural modifications introduced within the network matrix owing to the variations in cross-linker and dopant concentrations.