Statistical and block copolymerization of poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) macromonomers having an end-norbornenyl group was performed via ring opening metathesis polymerization, ROMP, to produce the corresponding statistical and block brush copolymers consisting of PLLA and PCL side chains on a polynorbornene, PNBE, backbone. The molecular characteristics of the macromolecular brushes were determined by 1 H-NMR spectroscopy and Size Exclusion Chromatography equipped with various detectors. These complex topologies allow addressing important questions on the physics of semicrystalline polymers. These include the role of (i) a doubly grafted PCL or PLLA chain on