ABSTRACTThe conversion of polymeric waste into useful, value added material is considered as an efficient method for polymeric waste management because of the environmental issues caused by such materials. This work proposes a simple, cost‐effective strategy for the conversion of expanded polystyrene waste into polystyrene nanoparticles via nanoprecipitation. In this method, expanded polystyrene is dissolved in a suitable solvent for example, tetrahydrofuran and added to a nonsolvent, such as water, to precipitate polystyrene nanoparticles of diameter less than 500 nm. The study also investigates the influence of various process parameters such as, initial concentration of expanded polystyrene, the speed of stirring, the solvent to water volume ratio and the solvent type used for nanoprecipitation, on the size and polydispersity of the precipitated PS nanoparticles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42904.