CO2-switchable polymer-hybrid silver nanoparticles and their gas-tunable catalytic activity

Abstract

The design of controllable or “signal-triggered” metal nanoparticles is one of the emerging trends in nanotechnology and advanced materials. CO₂-switchable polymer-hybrid silver nanoparticles (AgNPs) were prepared by a one-pot reaction reducing AgNO₃ and trithioester terminated PDEAEMA with sodium borohydride (NaBH₄). The hybrids showed a long-term stability, and their size and size distribution can be easily modulated by tuning the molar ratio of polymers to AgNO₃. The hybrids not only exhibit hydrophobic–hydrophilic transitions in immiscible mixed solvents, but also undergo a switchable dispersion/aggregation states upon alternately treating with CO₂ and N₂. Moreover, this smart hybrid was preliminarily used as catalyst for the reduction of 4-nitrophenol. The catalytic activity of the hybrids can be switched and monotonously tuned by varying the flow rate of CO₂ purged into the reaction system, which may open a new avenue for tailoring the catalytic activity of metal nanoparticles toward a given reaction.