A polymer drug delivery system was developed using crosslinked self-assembled micelles, which form stable coreshell particles. The block copolymer, composed of poly [poly (ethylene glycol) methyl ether methacrylat-block-[poly (methyl methacrylate-p-nitrophenyl acrylate)] [P(PEGMEMA)-b-P(MMA-NPA)], was synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. The self-assembled micelles were stabilized by core crosslinking through the reaction of p-nitrophenyl acrylate with 1,8-octandiamine forming stable coreshell particles.