Design and synthesis of highly efficient branching agent ("inimer") to prepare hyperbranched architectures with tunable physical and chemical properties is one of the most challenging and interesting topic to the polymer community. Here, we report the rational design of a new polyhedral oligomeric silsesquioxane (POSS) containing "inimer" and employed in reversible addition-fragmentation chain transfer (RAFT) copolymerization with various vinyl monomers such as styrene (St), polyethylene glycol methyl ether methacrylate (PEGMA) and N,N-dimethyl acrylamide (DMA) to develop novel hybrid hyperbranched copolymers. Degree of branching (DB) and average repeat unit per branch (RB) of the resulting hyperbranched copolymers have been fine-tuned by altering the [monomer]/[inimer] ratios. Hyperbranched copolymers such as poly(St) and poly(PEGMA) were successively employed to prepare star-shaped polymers with controllable arm length. Self-assembly behavior of star-shaped polymers was investigated in methanol, where a wide spectrum of morphologies including sphere, ellipsoid and vesicle could be achieved simply via tuning the availability of POSS moiety, DB of the methanophobic hyperbranched core and/or the length of methanophilic arms. (C) 2016 Elsevier Ltd. All rights reserved.