Shape engineering of polystyrene particles from spherical to raspberry-like to hollow flower-like: Via one-step non-surfactant selflating polymerization of styrene in ethanol-water mixtures

We report a facile method for preparation of polystyrene (PS) particles with spherical, raspberry-like, and hollow flower-like structures by single-step non-surfactant selflating polymerization of styrene in ethanol-water mixtures. PS particles with diverse morphologies could be easily obtained by simply adjusting the volume ratios of the styrene/water/ethanol mixture and initiator-ethanol-water mixture. By decreasing this ratio, the particles with spherical, raspberry-like, and hollow flower-like structures were obtained in sequence. The wettability of the coatings changing from hydrophilicity to hydrophobicity was easily tuned by the PS particles with different roughnesses. A competitive mechanism of interfacial polymerization and exudation was proposed to interpret the formation of PS particles with diverse morphologies.