One-step preparation of magnet-responsive amphiphilic nanoparticles for efficient oil collection

Waste oil collection is crucial for environmental protection. However, the preparation of magnet -responsive amphiphilic nanoparticles (NPs) for oil emulsification and collection generally involves multiple steps, greatly limiting their widespread applications. Here, magnet -responsive amphiphilic NPs are designed and prepared in a single step via co -precipitation and self -assembly. Upon rapid solvent exchange, shellac, poly(lactic acid) (PLA) and PLA-poly(ethylene glycol) (PLA-PEG) co -precipitate around Fe 3 O 4 NPs, which serve as nuclei for the nucleation and growth of the magnet -responsive amphiphilic NPs. Each Fe 3 O 4 @PLA-PEG/shellac NP is consisted of two distinct bulbs, one hydrophobic shellac bulb and the other hydrophilic PLA bulb with PLA-PEG on the surface. The NPs show excellent amphiphilicity and performances in stabilizing oil -in -water and water -in -oil emulsions. By tuning the NP shape, the control of the oil/water interfacial curvature and thus the emulsion type has also been demonstrated. Once the oil phase is emulsified and stabilized by Fe 3 O 4 @PLA-PEG/shellac NPs, waste oil could effectively be collected by applying a magnetic field, showing good performances in waste oil removal. The method using magnet -responsive amphiphilic NPs presents a simple and green way for rapid and efficient oil collection and removal. In addition, the developed one-step strategy also provides a facile platform to prepare functional amphiphilic NPs for diverse applications, such as oil collection, drug delivery and bioimaging.