We report the synthesis and ion-binding properties of four poly(crown-ethers) displaying either one or two crown-ethers (15-crown-5 or 18-crown-6) on every third carbon alongside the backbone. The polymers were synthesized by living anionic ring-opening polymerization of disubstituted cyclopropane1,1- dicarboxylates monomers. Cation binding of the polychelating polymers and corresponding monomers to Na+ and K+ was evaluated by picrate extraction and isothermal calorimetry titration. This novel family of poly(crown-ethers) demonstrated excellent initial binding of the alkali ions to the polymers, with a higher selectivity for potassium. (c) 2014 Wiley Periodicals, Inc.