To design high-performance poly(lactide)-based materials (PLA-based) with improved toughness, two approaches based on the reactive extrusion (REx) process are investigated and compared in the present study. The first approach relies upon a two-step procedure using a REx-polymerized poly(ethylene glycol) methyl ether acrylate, i.e., poly(AcrylPEG), as a highly-branched and compatible impact modifier for PLA. The free-radical polymerization proves to be very efficient with a peroxide initiator concentration of 1 wt%. The as-produced poly(AcrylPEG) is then melt-blended with PLA by extrusion. The resulting materials exhibit largely increase impact resistance (ca. 35 kJ/m(2)) in presence of 20 wt% poly(AcrylPEG) in comparison with neat PLA (2.7 kJ/m(2)), while moderate ductility (tensile elongation at break <40%) and limited plasticization effect are observed. The second one-step approach consists in in situ grafting of AcrylPEG onto PLA backbone via a one-stage REx. The resulting materials exhibit substantially improved impact resistance (ca. 102 kJ/m(2)) for AcrylPEG loading of 20 wt%, high ductility (tensile elongation at break of ca. 150%) and efficient plasticization. A detailed characterization of the morphology of the materials has been performed using PF-QNM-AFM to better elucidate the structure-property relationships. POLYM. ENG. SCI., 55:1408-1419, 2015. (c) 2015 Society of Plastics Engineers