Macromolecular photoinifiators have atthacted much attention in the recent years. They combine the properties of polymers with those of low-molecular weight photoinitiators. These are polymers having side-or main-chain photoreactive groups and can be used to make tailor-made graft and block copolymers. Benzoin is an important photoinitiator, and polymers containing terminal photoactive benzoin group can initiate polymerization of vinylic monomers to give block copolymers. In the present case, we report the synthesis Of polyurethane macrophotoinitiator with benzoin end group, which was subsequently used to synthesize polyurethane-polymethyl methacrylate block copolymers. The block copolymers were characterized by FTIR, H-1 NMR, TGA, scanning electron microscopic analysis, and solution viscometry studies. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 3089-3093,2009