A series of well-defined azide polymers, poly(styrene-co-4-vinylbenzyl azide) with different content of azide groups, were synthesized by RAFT polymerization. The single-chain polymeric nanoparticles were then facilely prepared via single polymer chain collapse and intramolecular crosslinking reaction of the azide polymer in a dilute solution at room temperature under UV irradiation within several minutes. The polymeric nanoparticles were characterized with H-1 NMR, GPC, DSC, TEM and DLS measurements, and the mean diameter of the nanoparticles was evaluated to be 5.5 +/- 0.8 nm in the dry state. Furthermore, the polymeric nanoparticles containing azide groups were successfully used to prepare the single-chain polymeric fluorescent nanoparticles via click reaction with N-propargyl carbazole. (C) 2014 Elsevier Ltd. All rights reserved.