Photoresponsive amphiphilic diblock poly(carbonate) s mPEG(113)-b-PMNCn with pendent o-nitrobenzyl ester group were synthesized through ring-opening polymerization (ROP) using 1,8-diazabi- cyclo[5.4.0] undec-7-ene (DBU) as catalyst and monomethoxy poly(ethylene glycol) (mPEG) as macroinitiator. In aqueous solution, the copolymers can self-assemble to spherical micelles with a PC core and a PEG shell. The critical micelle concentration (CMC), size, and morphology of the micelles were demonstrated by means of fluorescence spectroscopy, transmission electron microscopes (TEM), and dynamic light scattering (DLS). Under UV light irradiation, the amphiphilic copolymer micelles disassembled because of the photocleavage of o-NB ester, and the light-controlled release behaviors of payload Nile red were further proved. This study provides a convenient way to construct smart poly(carbonate) s nanocarriers for controlled drug release. (C) 2017 Wiley Periodicals, Inc.