Loading of Au nanoparticles (AuNPs) onto environmentally sensitive polymer microgels is increasingly used to regulate their optical properties and catalytic activities. Herein, we synthesized composite polymer microgels composed of poly(N-isopropylacrylamide-co-3-methacryloxypropyltrimethoxysilane)/poly(acrylic acid) with a core–shell structure, and AuNPs were controllably loaded onto/into the network chains of the polymer microgels using seed-mediated growth. The prepared AuNPs composite materials possessed good pH sensitivity; the electromagnetic coupling between the AuNPs could thus be tuned via the swelling/deswelling of the polymer microgels under various acidic/alkaline conditions. More importantly, the coordination interaction between the carboxyl groups in the PAA chains and Cu2+ ions changed by varying the copper ion content under various pH conditions, thus enabling regulation of the localized surface plasmon resonance of the AuNPs. These structural features of the prepared composite microgels enabled to tailor the optical performance of the AuNPs by varying the pH of the surrounding medium.

Poly(styrene-co-N-isopropylacrylamide)/poly(N-isopropylacrylamide-co-methacrylic acid)/polypyrrole-silver [P(St-NIPAM)/P(NIPAM-co-MAA)/PPy-Ag] composite microgels were synthesized via a one-step redox polymerization of silver ammonia ions and pyrrole monomer at room temperature, using the core–shell P(St-NIPAM)/P(NIPAM-co-MAA) thermo-sensitive polymer microgels as templates. The structure, component, and properties of the as-prepared composite microgels have been characterized by transmission electron microscope, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and UV–Vis spectrophotometer. The results indicate that the size and the dispersity of the formed PPy-Ag nanocomposite particles can be regulated by adjusting the initial concentration of the precursors. The catalytic activity for the reduction of 4-nitrophenol was regulated by varying the environment temperature. Meanwhile, the higher catalytic activity is contributed to the electron transfer from the conductive polymer PPy to the Ag nanoparticles in the polymer material matrix.

Styrene (St) and methacrylic acid (MAA) copolymers were synthesized by emulsion polymerization using Fe3O4 particles modified by oleic acid as central components. P(St-MAA)-Fe3O4/PPy (polypyrrole) core–shell composite microspheres with conducting and supermagnetic behaviors were obtained via in situ chemical oxidative polymerization on the surface of the P(St-MAA)-Fe3O4 magnetic composite microspheres. The –COOH groups in the composites acted as co-dopants in the formation of PPy and adsorbed the pyrrole monomers onto the surface of P(St-MAA)-Fe3O4. The P(St-MAA)-Fe3O4/PPy composite microspheres have been extensively characterized by transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The Fe3O4 particles were coated within P(St-MAA) polymers when the volume ratio of MAA to St was maintained at 1:5 during the co-polymerization process. The P(St-MAA)-Fe3O4/PPy multi-component composite microspheres show excellent superparamagnetism. The electrical conductivity of the composite microspheres largely depended on the PPy loading amount in the outer layer.Graphical abstractA simple route for the synthesis of P(St-MAA)-Fe3O4/PPy core–shell composite materials with excellent conducting and superparamagnetic behaviors.Highlights► We propose a simple route for the synthesis of P(St-MAA)-Fe3O4/PPy composite materials. ► The composites exhibit excellent superparamagnetic behavior with various saturation magnetizations. ► The electrical conductivity of the composites directly depends on the PPy loading amount in the outside layer.