Cation conductivity in dried poly(4-styrene sulfonate) poly(diallydimethylammonium chloride) based polyelectrolyte complexes

Polyelectrolyte complexes (PEC) are formed by ionic cross-linking of poly(4-styrene sulfonate) (PSS) and poly(diallydimethyl ammonium chloride) (PDADMAC) and subsequent removal of excess salt by dialysis. This systematic study provides temperature-dependent conductivity and other transport properties of dried PEC of type x PSS (Li, Na or Cs)·(1-x) PDADMAC with molar fractions x ranging from 0.4 to 0.6. In this way, the remaining counterions are either alkali cations or chloride anions with a number density determined by the composition, x. Conductivity and activation enthalpy values show that in all cases the alkali cations dominate the conductivity, even in anion-rich PEC. With increasing size of the alkali cation the conductivity values decrease, while the activation enthalpy values increase. Ion size thus is a parameter controlling the charge carrier mobility. In addition, the cation mobility is strongly dependent on cation concentration. The mobility of the anions is negligible, thus dried PEC are predominantly cation-conducting materials, irrespective of their composition.