| The synthesis of magnetic nanomaterials and magnetic nanocomposites is one of important fields in nano-material research. In the dissertation, we have first demonstrated a green synthetic approach for preparing superparamagnetic Fe3O4 nanoparticles usingα-D-glucose as a reducing agent. The other methods including in-situ reduction, co-embedding method, suspension polymerization etc., have been used to synthesize other nanocomposites such as bifunctional Fe3O4/Se one-dimensional (1D) nanoplank bundles, Fe3O4/Se/PANI nanocomposites, magnetic dialdehyde starch nanoparticles and Fe3O4/P(St-AA) magnetic polymer microspheres. The composition, construction and properties of the products have also been investigated.The main results can be summarized as follows:1. Superparamagnetic Fe3O4 nanoparticles were synthesized by green synthetic approach using a-D-glucose as a reducing agent and gluconic acid (the oxidative product of glucose) as stabilizer and dispersant without any additional stabilizer and dispersant. The results showed that the inverse spinel structure pure phase polycrystalline Fe3O4 was obtained, and the average size of Fe3O4 nanoparticles was about 12.5 nm, and the sample was similar to well dispersed Fe3O4 nanoparticles with narrow size distribution, and that the magnetic hysteresis loop at 300 K showed a saturation magnetization of 60.5 emu/g without coercivity and remanence. Because this method is very simple and easy under mild reaction condition, it might provide a new, mild, green, and economical route for the synthesis of other nanomaterials.2. Novel uniform straw-like Fe3O4/Se one-dimensional (1D) nanoplank bundles can be successfully prepared without any additional cross-linking agent and dispersant by in-situ reduction method since SeO32- (Se(Ⅳ)) anions could be adsorbed onto the surface of Fe3O4 nanoparticles. The width, thickness and length of as-prepared nanoplanks could be observed in the range of 300-400 nm,50 nm, and 6-8 μm, respectively. Fe3O4 nanoparticles might act as seeds and catalytic agent for the formation of the bifunctional nanocomposites. The products are of both fluorescent and superparamagnetic properties. More importantly, quantum size effect, which was reflected by marked blue shift of the band gap and direct transitions relative to the values of bulk t-Se, could be observed. The formation mechanism could be described as the linear aggregation and growth of Fe3O4/Se nanospheres, and the self-assembly of 1D Fe3O4/Se nanoplanks. The strawlike Fe3O4/Se could also be potentially converted to a series of bifunctional nanocomposites (e.g., Fe3O4/Ag2Se, Fe3O4/Bi2Se3, and Fe3O4/CdSe) with special morphology via the sacrificing template method. Moreover, the novel bifunctional nanocomposites would open up a potential application in microelectronics, biology, and medicine. Fe3O4/Se/PANI nanocomposites can also be obtained by in situ chemical oxidative polymerization in the presence of SeO32- anions.3. On the base of the previous study, superparamagnetic Fe3O4 nanoparticles were also obtained using hydrolysis product of starch i.e.α-D-glucose as the reducing agent, magnetic dialdehyde starch nanoparticles were successfully prepared with epichlorohydrin as crosslinker and dialdehyde starch (DAS) as wrapper by co-embedding method, and bovine serum albumin (BSA) as model drug was immobilized on the suface of magnetic dialdehyde starch nanoparticles. The particle size distribution of magnetic dialdehyde starch nanoparticles was 50-150 nm, and the average size was about 100 nm. The content of aldehyde group was 59.5%, and the package rate of DAS was 33.2%. The ratios of loading and coating of magnetic dialdehyde starch nanoparticles with BSA were 5.0% and 54.4%, respectively. The saturation magnetization of magnetic dialdehyde starch nanoparticles at 300 K was 29.5 emu/g without coercivity and remanence. The as-prepared products might have potential applications such as drug carrier and targeted drug release.4. Fe3O4/poly(styrene-co-acrylic acid) magnetic polymer microspheres were synthesized by suspension polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe3O4 nanoparticles modified with oleic acid as magnetic nuclei,and poly(styrene-co-acrylic acid) [P(St-AA)] as shell. Drug-loading capacity of magnetic polymer microspheres with curcumin as model drug was also studied. The results indicated that magnetic polymer microspheres with monodisperse were obtained, the particle size distribution was 50-120 nm, and the average size was about 100 nm. The contents of P(St-AA) and Fe3O4 nanoparticles in magnetic polymer microspheres were 74% and 24.7%, respectively. The ratios of loading and coating of magnetic polymer microspheres with curcumin were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer microspheres at 300 K was 20.2 emu/g without coercivity and remanence.
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