Platinum nanoparticles generated in spherical polyelectrolyte brushes and their high catalytic activity

Nano‐sized cationic spherical polyelectrolyte brushes (SPBs) consisting of a solid core of polystyrene and a shell of poly(aminoethyl methacrylate hydrochloride) grafted densely on the core were prepared by photo‐emulsion polymerization. They were found to be ideal nanoreactors to generate platinum (Pt) nanoparticles. Because of Donnan equilibrium, SPBs can concentrate and confine the divalent PtCl62− ions as counterions within the brush layer. The PtCl62− ions were reduced into Pt particles with an average size of 3 nm by sodium borohydride (NaBH4) in situ. The prepared Pt nanoparticles were stably immobilized in SPB and showed high catalytic activity in the reduction of p‐nitrophenol to p‐aminophenol by NaBH4. The results reported here suggest that spherical polyelectrolyte brushes are ideal nanoreactors for the preparation of Pt nanoparticles.