Nanoparticle Capture by Spherical Polyelectrolyte Brushes and Its Grading Separation Assisted by Compressed CO2

Abstract

Spherical polyelectrolyte brushes (SPBs) could capture some charged nanoparticles, due to the Donnan effect, that have been verified as promising carriers for nanoparticles. However, how to separate the nanoparticles and recycle the expensive polymer brushes is still an obstacle in industrial applications. Compressed carbon dioxide (CO2) could work as a “pressure trigger” to regulate the properties of mixed solvents to accomplish the separation process because of its antisolvent effect. Herein, Ag nanoparticles were in situ synthesized in the spherical poly(acrylic acid) brushes with a polystyrene core (PS–PAA) and recovered easily by a suitable pressure of compressed CO2, while PS–PAA still remained in solution. After temperature quenching and depressurization, Ag nanoparticles could be collected with nearly 100% recovery ratio and narrow distribution. Moreover, further increased pressure could induce the aggregation of PS–PAA later, which could be employed to recycle the polymer brushes without any stru...