Pd nanoparticles immobilized on pH-responsive and chelating nanospheres as an efficient and recyclable catalyst for Suzuki reaction in water

Abstract

The pH-responsive and chelating core-shell nanospheres of polystyrene-co-poly[2-methacrylic acid 3-bis(carboxymethylamino)-2-hydroxypropyl ester] (PS-co-PGMA-IDA), which contain a PS core and a pH-responsive and chelating shell of PGMA-IDA, are synthesized by one-stage soap-free emulsion polymerization and used as scaffold to synthesize Pd nanoparticles embedded in the shell layer of the core-shell nanospheres. This catalyst of shell-embedded Pd nanoparticles is highly dispersed in aqueous medium at pH range from 3 to 11 just like a homogeneous catalyst and can be separated and reused like a heterogeneous one by adjusting pH value of the aqueous medium. The Suzuki reaction performed in water demonstrates that the shell-embedded Pd catalyst is an efficient and easily reusable one. Compared with the Pd catalyst of nanoparticles immobilized on the core layer of core-shell microspheres, the present shell-embedded Pd catalyst is more efficient possibly due to easier access to the active sites of the Pd nanoparticles immobilized on the outer shell of the core-shell nanospheres.