A series of well-defined centipede-like copolymers with poly(glycidyl methacrylate) (PGMA) as main chain and poly(L-lactide) (PLLA) and polystyrene (PSt) as side chains have been synthesized successfully by combination of ring-opening polymerization and atom transfer radical polymerization (ATRP). The synthetic process includes three steps. (1) Synthesis of PGMA via ATRP; (2) preparation of macroinitiator with one bromine group and a hydroxyl group at every GMA unit of PGMA; (3) ring-opening polymerization of LLA and ATRP of St to obtain the asymmetric centipede-like copolymers. The number-average degrees of polymerization of PGMA backbone, PLLA and PSt side chains were determined by H-1-NMR spectra, and the molecular weights of the resultant intermediates and centipede-like copolymers were measured by gel permeation chromatography. The molecular weight distributions were narrow and the molecular weights of both the backbone and the side chains were controllable. The thermal behavior of the centipede-like copolymers was investigated by differential scanning calorimeter. With the increase of PSt side chain length, the glass transition temperature of PLLA side chains shifted to high temperature, and crystallization ability of PLLA side chains became poor. (C) 2008 Wiley Periodicals, Inc.