Cross-linked sterically stabilized latexes were synthesized by emulsion polymerization of 2-(diethylamino)ethyl methacrylate using a bifunctional ethylene glycol dimethacrylate cross-linker and a poly-(ethylene oxide)-based macromonomer as the stabilizer.These latexes exhibit reversible swelling properties in water by adjusting the solution pH.At low pH

they exist as swollen microgels as a result of protonation of the tertiary amine units.Deswelling occurs above pH=7 [the effective pKa of poly(2-(diethylamino)ethyl methacrylate)]

leading to the formation of the original compact latex particles.PDEA-Pd nanocomposite particles were prepared via in situ reduction using NaBH4 as a reducing agent

based upon a polymer microgel template method.pH-responsive microgel-nano metal particle composite system can be prepared for catalyses which proceed under acidic conditions.The composite system of the microgel and the metal nanoparticles form homogeneous phase with the physics reaction

which can effectively improve the catalytic efficiency

and after completion of the reaction the system can be adjusted at alkaling conditions for recycling.TEM

UV-Vis

XRD and TGA were used to characterize Pd particle size

the PDEA-Na2PdCl4 composite microspheres interaction

Pd crystal form and Pd loadings.TEM images showed the Pd particle diameter was about 3.5 nm.The rate constant kapp for the reduction of 4-nitrophenol in presence of PDEA-Pd nanocomposite particles was studied by UV-Vis spectroscopy

which suggested the PDEA-Pd nanocomposite particles had good catalytic activity.The pH-responsive catalyst can be easily separated from the reaction mixture and readily recovered.