| This thesis contains the following contents:1. Preparation and Characterization of TiO2 Nanoparticles Functionalized by Temperature-sensitive poly(N-isopropylacrylamide)TiO2 nanoparticles functionalized by poly(N-isopropylacrylamide), PNIPAM in short, were prepared via seeded emulsion polymerization of N-isopropylacrylamide (NIPAM) in the presence of N, N′-methylenebisacrylamide (MBAA) as the crosslinking monomer. The morphology and structure of the TiO2/PNIPAM hybrid hydrogel were characterized by means of transmission electron microscopy (TEM), X-ray powder diffraction spectroscope (XRD), and Fourier transformation infrared spectroscopy (FTIR). At the same time, the response to temperature variation of the composite was also primarily investigated. The results indicated that the titled inorganic/organic hybrid had a sphere-like shape and was composed of TiO2 inorganic nanoparticles and biocompatible polymer matrix. And it had excellent thermo-sensitivity, as confirmed by the corresponding optical photographs at different temperatures. Thus this thermosensitive TiO2 nanoparticles may have potential use in the remediation of wasterwater steams.2. Preparation and Characterization of Environmentally Sensitive Polymer- matrix Hybrid Microgels Doped with Ag NanoparticlesHybrid microgels based on a responsive polymer and silver nanoparticles were prepared via surfactant-free polymerization and chemical reduction. Thus thermosensitive microgels were fabricated by surfactant-free polymerization of N-isopropylacrylamide (NIPAM) with N,N′-methylenebisacrylamide (NMBAA) in water at about 75°C. And silver nanoparticles were synthesized in-situ in the interiors of the polymeric microgels by reduction of silver nitrate with sodium borohydride, which gave birth to PNIPAM microgels doped with Ag nanoparticles (named as PNIPAM/nano-Ag hybrid microgels). The PNIPAM/nano-Ag hybrid microgels were characterized by means of transmission electron microscopy (TEM), Fourier transformation infrared spectrometry (FTIR), X-ray diffraction (XRD), and ultraviolet-visible light spectrometry (UV-Vis). It was found that the synthesized hybrid microgels possessed thermosensitive properties and excellent stability in aqueous solution. Namely, the hybrid microgels experienced transparent-to-opaque transformation as the temperature increased from 25°C to 35°C. The target hybrid microgels could be easily separated from reaction system, due to the PNIPAM network can open or close to a certain extent with temperature. Moreover, the hybrid microgels with combined advantages of the temperature responsiveness of the PNIPAM matrix and the activity of the doped Ag nanoparticles could have potential applications in photonics, catalysis, and separation technologies.3. Preparation and Characterization of Thermosensitive PNIPAM Coated Iron Oxide NanoparticlesA new and facile approach was established to fabricate thermoresponsive poly(N-isopropylacrylamide) (abridged as PNIPAM) coated iron oxide nanoparticles in a non-aqueous medium. The morphology and structure of the nanoparticles-doped composite were analyzed by means of transmission electron microscopy (TEM), X-ray power diffraction (XRD), and Fourier transformation infrared spectrometry (FTIR). The thermosensitivity of the composite was also investigated. Results indicated that the oil-soluble iron oxide nanoparticles encapsulated with PNIPAM, composed of inorganic iron oxide core and biocompatible PNIPAM shell, were dispersed well in water and had sphere-like shape. The PNIPAM-coated iron oxide nanoparticles with such a kind of core-shell structure showed excellent thermosensitivity. Namely, the aqueous suspension of PNIPAM-coated iron oxide nanoparticles dramatically changed from transparent to opaque as the temperature increased from room temperature to 38°C, showing potential as optical transmittance switch materials and significance in the fields of protein adsorption and purification, controlled release, and drug delivery. |
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