Spherical Polyelectrolyte Brushes on Colloidal Poly(butadiene) Particles

A novel method to prepare spherical polyelectrolytc brushes (SPB) on the surface of colloidal poly(butadiene) (PB) core without having to use initiators with C=C double bond to attach covalently on the core surface was reported. Making use of the abundant double bonds in PB, spherical poly(acrylic acid) (PAA) bushes were grown from PB core surface by direct thermo-initiated emulsion polymerization using KPS as initiator. The thickness of SPB increased significantly upon increasing pH and decreasing the ionic strength. The grafting density of SPB with PB core was estimated from the relationship between the brush thickness and ionic strength based on the modified Daoud-Cotton model. The grafting density of SPB prepared by thermo-initiated emulsion polymerization (0.122 nm(-2)) is higher that that of SPB by photo-emulsion polymerization (0.105 nm(-2)). Using SPB with PB core as nanoreactors, nickel and silver nanoparticles were prepared by reduction of Ni2+ and Ag+ absorbed inside SPB as counterions. Relatively high catalytic activities for the reduction of p-nitrophenol by NaBH4 were observed for SPB immobilized Ni or Ag nanoparticles.