Hybrid particle brushes and star polymers with a core-shell architecture were prepared via atom transfer radical polymerization (ATRP) and incorporated into bulk poly(methyl methacrylate) (PMMA) in order to improve the toughness and ductility of glassy, transparent PMMA. Mechanical and optical characterization demonstrated an improvement in both the strength and the toughness of the reinforced materials without significantly compromising the optical transparency. (C) 2017 Elsevier Ltd. All rights reserved.