A new class of ionomer was developed through the grafting of acrylic acid onto a metallocene-based poly(ethylene octene) elastomer, followed by its neutralization with zinc acetate. The ionomeric product was characterized through Fourier transform infrared spectroscopy, small-angle X-ray scattering, and transmission electron microscopy studies. The effect of the crystallinity and pendent chain length on the ionomeric modification was also studied through the variation of the level and nature of comonomer, respectively. The impact of these ionomeric modifications on various physicomechanical properties was thoroughly investigated with differential scanning calorimetry and mechanical, dynamic mechanical, and thermogravimetric analysis, and the resulting properties were correlated with the structure of the modified elastomers. The ionomerization of the base elastomers caused a significant improvement in the mechanical and thermal properties compared to the corresponding pristine elastomer. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3906-3914, 2009