Nano Silver / Polymer Composite Micro-gel Preparation And Performance Research

Metallic Ag nanoparticles and sensitive polymer microgels were combined by the appropriate way. The three-dimensional network structure of microgels could better limit the size distribution of preparing metal nanoparticles, avoid metal nanoparticles aggregation and improve the stability of metal nanoparticles. Moreover, the physical and chemical properties of metallic Ag nanoparticles could be controlled by adjusting the distance between metal nanoparticles via varying the environmental conditions (temperature, pH).Based upon our group's previous research work, this thesis mainly studied on the synthesis, characterization and related properties of sensitive composite microgels containing Ag nanoparticles. This work involves three parts:(1) Thermo-sensitive poly(styrene-co-N-isopropylacrylamide)/poly(N-isopropylacrylamide) (P(St-NIPAM)/PNIPAM) and temperature and pH double responsive poly(styrene-co-N-isopropylacrylamide)/poly(Methacrylic acid-co-N-isopropylacrylamide) (P(St-NIPAM) /P(MAA-co-NIPAM)) composite microgels with core-shell structures were synthesized by two-step reaction including a surfactant-free emulsion polymerization and a seed emulsion polymerization method. The prepared composite microgels exhibited better spherical morphologies and well monodisperse. The structure, component and properties of the prepared composite microgels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and laser particle size analyzer. It was demonstrated that the thermo-sensitive behavior of P(St-NIPAM)/PNIPAM composite microgels enhanced with increasing the PNIPAM content of shell layer. The thermo-sensitive behavior of P(St-NIPAM) /P(MAA-co-NIPAM) was reduced with increasing the MAA contents in the copolymer composite. Whereas, the pH-sensitive behavior of P(St-NIPAM)/P(MAA-co-NIPAM) was enhanced. Therefore, to control the pH sensitivity of the composite microgels could be realized by changing MAA content in the copolymer.(2) P(NIPAM-St)/PNIPAM-Ag composite microgels loaded with Ag nanoparticles were prepared via polymer microgel template technique in the atmosphere of ammonia gas, using alcohol as reducing agent. The structure, component and properties of the prepared composite microgels were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), UV-Vis spectrophotometer (UV-vis))and laser particle size analyzer. It was demonstrated that P(St-NIPAM)/PNIPAM-Ag composite microgels also showed thermosensitivity, and the thermoresponsive behavior became weaken with the increasing of the loading amount of Ag nanoparticles in the shell layer. In addition, P(St-NIPAM)/PNIPAM-Ag composite microgels had excellent catalysis performance for reduction 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 45 min.(3) P(NIPAM-St)/P(MAA-co-NIPAM)-Ag composite microgels loaded with Ag nanoparticles were prepared via polymer microgel template technique in the atmosphere of ammonia gas, using alcohol as reducing agent. The structure, component and properties of the prepared composite microgels were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), UV-Vis spectrophotometer (UV-vis))and laser particle size analyzer. It was demonstrated that P(St-NIPAM)/PNIPAM-Ag also showed thermo-and pH sensitivity. Compared with the template, the thermo-and pH sensitive of Ag nanoparticles composite microgels was weaken to some degree, because of Ag nanoparticles was inserted into the polymer chain network and the interaction between Ag nanoparticles and polymer chain. In addition, P(St-NIPAM)/P(MAA-co-NIPAM)-Ag composite microgels had excellent catalysis performance for reduction 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 12 min.