An ionomer is a polymer that comprises repeat units of both electrically neutral repeating units and a fraction of ionized units (usually no more than 15 percent). Ionomers have unique physical properties including electrical conductivity and isoviscosity -- increase in ionomer solution viscosity with increasing temperatures (see conducting polymer).
Some commercial applications for ionomers are golf ball covers, semipermeable membranes, sealing tape and thermoplastic elastomers.