The structure-property behavior of two types of elastomeric telechelic ionomers has been investigated. Sulfonated polyisobutylene telechelic ionomers were studied in both bulk and solution. The bulk mechanical properties of carboxylated polyisoprene telechelic ionomers were also investigated. The sulfonated polyisobutylene telechelic ionomers are available in three different molecular architectures - linear monofunctional, linear difunctional, and three-arm star trifunctional. These materials, which had previously been neutralized only with monovalent and divalent cations, were neutralized with cerium(III) and lanthanum(III). These trivalent cations resulted in a material with improved network stability over those materials previously studied. Long term stress relaxation and creep experiments revealed that at short times the networks are stable while the materials flow after about one week of relaxation. Studies of the solution behavior of the sulfonated polyisobutylene telechelic ionomers concerned dilute solution viscometric behavior in nonpolar solvents and nonpolar-polar solvent mixtures as well as the viscoelastic behavior of more concentrated solutions in nonpolar solvents. Gelation was observed in nonpolar solvents at concentrations as low as 1-2 g/dl. The gelation concentration is dependent upon molecular architecture, molecular weight, neutralizing cation type, and excess neutralizing agent. The viscosity of these ionomers in nonpolar-polar solvent mixtures may increase with increasing temperature due to the temperature -dependent equilibrium between the ionic groups, the polar cosolvent, and the nonpolar solvent. More concentrated solutions or gels in nonpolar solvents display a unique viscoelastic behavior which is very dependent upon architecture, molecular weight, and neutralizing cation. Solutions of ionomers (5 g/dl) neutralized with zinc display a low-frequency viscous region and a high-frequency elastic region at room temperature. Solutions of ionomers neutralized with more ionic cations display an elastic response over essentially the entire frequency range. Storage and loss modulus curves obtained at different temperatures do not superpose, and these solutions are thus thermorheologically complex. The bulk mechanical properties of carboxylated polyisoprene telechelic (linear) ionomers were studied. For materials neutralized with Group IA or IIA metals, resistance to flow was found to increase with decreasing ionic radius. The zinc-neutralized material flowed with little resistance, while the nickel-neutralized material exhibited the best elastomeric characteristics. Materials neutralized with titanium(IV) required a fourfold stoichiometric excess to reach maximum strength due to the difference in neutralization pathway. An amine-terminated polybutadiene crosslinked with copper(II) chloride displayed greater strength and network stability than any of the carboxylated polyisoprene telechelic ionomers. / Ph. D.