Well-defined diblock copolymers of linear polyethylene (PE) and poly(dimethylsiloxane) (PDMS) have been synthesized through a facile route combining the thiol-ene click chemistry of vinyl-terminated polyethylene (PE-ene) and the sequential esterification reaction. The resulting diblock copolymers are characterized by H-1 NMR, FT-IR, DSC, TGA, and TEM. In addition, the PE-b-PDMS diblock copolymers have been evaluated as compatibilizers in the blends of high-density polyethylene (HDPE) and silicone oil. The morphological analysis and mechanical properties demonstrate that the compatibilized blends with low loading concentration of PE-b-PDMS display significant improvements in modulus of elasticity and elongation at break as compared to the uncompatibilized binary blends. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3205-3212