Polylactic acid-backbone graft and bottlebrush copolymers are synthesized by polymerizing a lactide-functionalized macromonomer using ring opening polymerization (ROP). In some embodiments of the present invention, the macromonomer is a lactide-functionalized polymer that may be synthesized by, for example, polymerizing a monomer capable of undergoing radical polymerization (e.g., styrenic, vinylic, acrylic, etc.) using a brominated lactide initiator via atom transfer radical polymerization (ATRP). The brominated lactide initiator may be 3-bromo-3,6-dimethyl-1,4-dioxane-2,5-dione prepared by, for example, reacting lactide with N-bromosuccinimide in the presence of benzoyl peroxide.