We report a novel blue light initiated aqueous reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA) with a poly (glycerol monomethacrylate) homopolymer as the macro-RAFT agent and sodium bis(acyl)phosphane oxide (SBAPO) as the photoinitiator. High monomer conversions were achieved within 1h of blue light irradiation. Taking advantage of the temperature-insensitive feature of photoinitiator, the effect of reaction temperature on the blue light initiated aqueous RAFT dispersion polymerization was studied in detail. A new morphological phase diagram was constructed for the first time by changing the degree of polymerization (DP) of the core-forming block and the reaction temperature. Moreover, a typical morphological phase diagram for the blue light initiated aqueous RAFT dispersion polymerization at 70 C-degrees was also built and various morphologies have been prepared. Effect of wavelength of light (405 and 465 nm) on copolymer compositions and morphologies was studied. Finally, a fully one-pot blue light initiated aqueous RAFT polymerization was developed for the synthesis of various diblock copolymer nano-objects. (C) 2018 Elsevier Ltd. All rights reserved.