The associative and mechanical properties of magnesium neutralized telechelic poly(ethylene butylene) ionomer, CTPEB-Mg, in a nonpolar solvent of decalin were studied from very dilute solution up to the bulk in the range of temperature from 15 to 55 degreesC with theological methods and dynamic light scattering (DLS) technique. Dilute solution viscometry and DLS revealed that CTPEB-Mg molecules are associated as ring polymer in very dilute solution, followed by linear association of rings above polymer concentration C = 1 wt%. The linearly associated rings formed huge polymeric clusters at around C = 10 wt%, where the viscosity eta of CTPEB-Mg solution increased thirty times over that of an esterified sample of CTPEB. A viscoelastic network was formed around C = 15 wt%, above which disengagement of the magnesium dicarboxylate (MDC) ionic bond played a deterministic role for relaxation of the network up to the bulk. In referring to viscosity behaviors of the prepolymer CTPEB as well as esterified samples, changes in dynamic viscoelasticity of the network with increasing C were found to be closely related to corresponding changes in the average size of ionic clusters as well as fractions of elastically effective chains and dangling loops emanating from ionic clusters. (C) 2004 Elsevier Ltd. All rights reserved.