Sulfonated poly(styrene-ethylene/butylene-styrene) triblock copolymer ionomers: Influence of absorbed water on dielectric properties

The present work has shown that a sulfonated poly(styrene-ethylene/butylene-styrene) (S-SEBS) triblock copolymer ionomer is a material capable of exhibiting dielectric constants on the order of hundreds of thousands. This discovery has suggested the possibility that this polymer, as well as other members of the class known as ionomers, might find use as transducer materials. The portion of electrostriction due to a phenomenon known as the Maxwell effect may allow improved strain performance and voltage requirements over other technologies that have been employed to date.; Experimental results for films with a certain sulfonation degree have shown dielectric constants on the order of epsilon' ∼ 100,000 and dielectric loss tangents near D = tan delta ∼ 0.3, when the material has been exposed to humid conditions. Experiments have indicated that water content in these ionomers is strongly correlated to the relative humidity of the environment in which they operate. Water uptake is thus a primary consideration for obtaining materials with high dielectric constants, well suited to electroactive applications. Additional considerations for such applications include the effect of water on the material's breakdown strength when subjected to an electric field, and its plasticizing effect on the modulus.