Organic/Inorganic Nanocomposite Particles: Design, Synthesis And Application

Organic/inorganic nanocomposite particles have been of great interest based on the fact that the inorganic enhance the optical,electrical,and magnetic properties while the organic offers the processing and biocompatibility.More recently,the synthesis of organic/inorganic nanoparticles with stimuli-responsive,antibacterial,and biocompatible properties has attracted special interest.In this dissertation,several different organic/inorganic nanoparticles including the poly(acrylic acid) (PAAc)-grafted silica nanoparticles,the silica/poly(methyl methacrylate-acryl amide)(PMMA-AM)core-shell nanoparticles,the silver nanoparticles embedded silica nanospheres,the PAAc-grafted magnetite nanoparticles,and the magnetite/poly(N-isopropylacryl amide) (PNIPAM)hollow nanocomposite microspheres have been successfully synthesized.In the first,vinyl bond modified silica nanoparticles were synthesized by modified stober method from tetraethoxysilane(TEOS),γ-methacryloxypropyltrimethoxysilane(MPS)in ethanol solution under base condition.Comparing with stober method,this process can easily obtain the vinyl bond modified silica nanoparticles.Silica-PAAc core-shell nanoparticles were successfully prepared via graft copolymerization of acrylic acid(AAc)onto vinyl bond modified silica NPs.Transmission electron microscopy(TEM)results indicated that the obtained micropheres have core-shell morphology.Fourier Transform Infrared(FTIR)analysis and X-ray photoelectron spectroscopy(XPS)measurements confirmed that the surface of the nanoparticles was polymer-rich,which was consistent with the core-shell morphology.The influence of the synthetic conditions,such as reaction time and AAc concentration on the graft yield of PAAc grafted silica NPs was investigated.Dynamic light scattering(DLS)analysis showed that the silica-PAAc core-shell nanoparticles possessed excellent stimuli response to pH and ion strengthen.Because of their pH-responsive behavior and small feature size,nanostructure devices designed from the smart silica nanoparticles have potential applications including sensors and membranes.Polymer/silica inorganic/organic composite core/shell nanoparticles bearing amino groups on the surface were prepared via emulsifier-free emulsion copolymerization of methyl methacrylate(MMA)and acrylamide(AM).The prepared composite nanoparticles were characterized using FTIR analysis,TEM,and thermogravimetric analysis (TGA).The results showed that the obtained composite nanoparticles have a core/shell structure,and the surface of the nanopartilces was polymer-rich which were consistent with the core/shell morphology.The influence of the synthetic conditions,such as MMA concentration and potassium persulfate(KPS)concentration on the graft yield of composite nanoparticles was investigated.Because of their surface bearing amino groups,the novel composite nanoparticles have potential application in cohesive material,coating material,and so on.Silver nanoparticles embedded on silica nanospheres were prepared by using ion-exchangeable PAAc grafted on the silica surface as soft template followed by chemical reduction.The prepared hybrid nanospheres were characterized using XPS,X-ray diffraction(XRD), TEM,ultraviolet visible absorption spectroscopy(UV-vis),and bactericidal activity measurement.The results suggest that mono-dispersed Ag nanoparticles with controllable diameters can be obtained on the surface of silica nanospheres by varying the Concentration of silver nitrate and the suspension pH value,and the hybrid nanospheres have excellent bactericidal activity and potential application as a bactericidal agent in biomedical fields.In addition,novel PAAc grafted magnetic magnetite nanoparticles have been prepared by grafting copolymerization of acrylic acid onto the MPS modified magnetite nanoparticles and characterized with FTIR,TEM and TGA.The results shows that the PAAc grafted magnetite nanoparticles have a core-shell structure and good dispersibility.The influence of synthetic conditions,such as reaction time,AAc concentration,KPS concentration and reaction temperature on the graft yield of PAAc grafted magnetite nanoparticles was investigated.The graft yield increased with the increasing reaction time and AAc concentration,however,had a maximum with the increasing initiator concentration and reaction temperature.Finally,stimuli-responsive hollow magnetite/poly(N-isopropylacryl amide)(PNIPAM)nanocomposite microsphere were synthesized via an interfacial polymerization approach at the interfaces of an inverse water/oil emulsion.TEM and magnetic properties results shown that the hollow microspheres with a wall thickness of about 100 nm and a size of about 1.2μm and they are superparamagnetic.