Microgel Load Nano-silver And Polypyrrole Composites And Its Performance

Silver nano-particles (Ag NPs) and conducting polymers were composited appropriately onto the surface of polymer microgels. An advantage is to prevent Ag NPs aggregation. Meanwhile, the physical and chemical properties of Ag NPs can be controlled effectively by altering the external environment conditions (temperature, pH, etc.). At the same time, conductive polymer could protect and stable nano-metal particles, and can also be used as a new conductive transfer for metal nanoparticles to improve conductivity and catalytic property of Ag NPs.Based upon our group's previous work, this thesis mainly focused on the synthesis, characterization and the related properties of polymer composite microgels which contain polypyrrole(PPy) and Ag NPs. The main work includes the following two parts:(1) Synthesis of composite microgels loading polypyrrole and Ag NPs by step-by-step redox methodUsing P(St-NIPAM)/P(NIPAM-co-MAA) composite microgels with core-shell structures as template, P(St-NIPAM)/P(NIPAM-co-MAA)/PPy composite microspheres were obtained on the surface of the polymer microgels, by means of in-situ chemical oxidative polymerization, based on the adsorption effect of carboxyl functional groups to pyrrole. After swelling of P(St-NIPAM)/P(NIPAM-co-MAA)/PPy composite microspheres using Tollens' reagent, multi-component P(St-NIPAM)/P(NIPAM-co-MAA)/PPy/Ag nano-composite materials were produced by the step-by-step oxidative polymerization, Tollens'reagent as the oxidant, and polypyrrole as the reducing agent. The structure, component and properties of the prepared composite microgels have been characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis spectrophotometer and laser particle size analyzer. It was demonstrated that P(St-NIPAM)/P(NIPAM-co-MAA)/PPy/Ag composite microgels showed the excellent catalytic performance and electrochemical performance. The Ag NPs of composite microgels have well monodispersity and uniformity, and the average particle size of Ag NPs is about5-15nm. In addition, P(St-NIPAM)/P(NIPAM-co-MAA)/PPy/Ag composite microgels had excellent catalysis performance for reduction4-nitrophenol (4-NP) to4-aminophenol (4-AP) within20min at room temperature.(2) Synthesis of composite microgels loading polypyrrole and Ag NPs by one-step redox methodSimilarly, using P(St-NIPAM)/P(NIPAM-co-MAA) composite microgels with core-shell structures as template, P(St-NIPAM)/P(NIPAM-co-MAA)/PPy-Ag nano-composite particles were synthesized by one-step chemical oxidative polymerization of pyrrole using Tollens'reagent as an oxidant. The structure, component and properties of the prepared composite microgels have been characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis spectrophotometer (UV-vis) and laser particle size analyzer. The result reveals that the P(St-NIPAM)/P(NIPAM-co-MAA)/PPy-Ag nano-composite particles still retain some thermo-sensitivity. It also showed that the prepared composite microgels loading polypyrrole and Ag NPs exhibited the excellent catalysis performance for reduction4-nitrophenol to4-aminophenol within15min at room temperature. Furthermore, the catalytic property of the nano-composites could adjust accordingly with the temperature variation.