Highly conducting lithium polyelectrolytes based on maleic anhydride styrene copolymers

Comblike polyelectrolytes comprising immobilized carboxylic anions and poly(oxyethylene) (OCH2CH2)(n) side chains of various length were obtained from the reaction of appropriate lithium alcoholates with maleic anhydride-styrene alternating copolymers. These materials may be fabricated as films of ambient temperature conductivity in the range of 10(-9)-10(-6) S.cm(-1), depending on the side-chain length. The conductivity values increase by 2-3 orders of magnitude after the addition of strong polar plasticizers such as dimethyl sulfoxide and propylene carbonate. A further increase in conductivity was observed after the complexation of carboxylic anions by BF3. On the basis of C-13 NMR studies and Li-7 NMR relaxation times of lithium carboxylates, it was found that the anion complexing agent reduces ion pairing in polyelectrolytes more effectively than cation-solvating solvents. The possible conduction mechanism in the solid and gel polyelectrolytes is discussed.