Polyethylene-poly(dimethylsiloxane) copolymers were synthesized in solution from an ethylene monomer and an omega-vinyl poly(dimethylsiloxane) (PDMS) macromonomer at 363 and 383 K with EtInd(2)ZrCl(2)/methylaluminoxane as a catalyst. The copolymers obtained were characterized with Fourier transform infrared spectroscopy, H-1 and C-13 NMR, size exclusion chromatography, and differential scanning calorimetry. The rheological properties of the molten polymers were determined under dynamic shear flow tests at small-amplitude oscillations, whereas the physical arrangement of the phase domains was analyzed with scanning electron microscopy (SEM)/energy dispersive X-ray (EDX). The analysis of the catalyst activity and the resulting polymers supported the idea of PDMS blocks or chains grafted to polyethylene. The changes in the rheological behavior and the changes in the Fourier transform infrared and NMR spectra were in agreement with this proposal. (C) 2004 Wiley Periodicals, Inc.