Polyurethane ionomers based on either poly(propylene glycol), PPG, or poly(ethylene glycol), PEO, and di- (4-isocyanatophenyl) methane, MDI, butane-1,4-diol and cis-2-butene-1,4-diol have been synthesized and characterized. Attempts to convert the unsaturated polyurethanes directly to ionomers by reaction with N-chlorosulphonyl isocyanate, CSI, followed by hydrolysis, failed due to the more favoured reaction of CSI with the labile hydrogen on the urethane linkage. Therefore, the cis-2-butene-1,4-diol was first converted to the dibenzoate which was then treated with CSI to form the β-lactam derivatives. Subsequent hydrolysis of these derivatives with tetra-n-butyl ammonium hydroxide solution produced ionic derivatives whilst at the same time regenerating the terminal -OH groups. These ionic diol intermediates were then used for synthesizing the polyurethane ionomers.