Preparation And Electrochemical Applications Of Functional Magnetic Nano Carbon-polymer Microsphere Composites

The functional magnetic polymer nanocomposite containing magnetic nanoparticles is a new type of functional material with strong magnetic responsiveness. In recent years as the research more deeply, functional magnetic polymer composite microsphere are widely used in cell separation, biological engineering, sewage treatment and other fields. With superparamagnetism, uniform particle size distribution, surface functionalization of high density functional groups magnetic carbon-composite polymer microspheres composite was prepared in this paper, modifying the electrodes and the electrochemical detection of biological molecules. The main results of this paper are listed as follows:1. Synthesized 11 nm and superparamagnetism Fe3O4 nanoparticles by the chemical co-precipitation method. Fe3O4 nanoparticles were modified with different surfactant 11 acid sodium(NaUA), alpha olefin sulfonate(AOS) and polyethylene glycol 400(PEG400), then choose the appropriate surfactants modification on the Fe3O4. The formation mechanism of magnetic coating layer and dispersion and the effect on the stability of the different quantities of surfactant on the magnetic fluids were studied.The Fe3O4 nanoparticles and magnetic fluid(MF) were characterized with FTIR, XRD, TEM, VSM and TG. The results show that after the surface modification of the magnetic particle, the size of NaUA-Fe3O4 is better and NaUA-Fe3O4 magnetic liquid can be dispersed in water stably. From the TEM images, NaUA-Fe3O4 nanoparticles dispersed uniformly and effectively prevent the reunion between the nanoparticles.TG curve to explain the mechanism of single and double layer coated magnetic nanoparticles, NaUA dosage of single, double surfactant modified nanoparticles NaUA dosage was 5%, 12% respectively. VSM results show that the NaUA-Fe3O4 have superparamagnetism,magnetic saturation magnetization of pure Fe3O4 was 49.18 emu/g, NaUA-Fe3O4 nanoparticles of saturation magnetization intensity was 44.34 emu/g.2. Core-shell structured Fe3O4/P(St-GMA-NaUA) magnetic polymer composite microspheres were synthesized with NaUA-Fe3O4 water-MF, styrene(St) and Methyl acrylic glycidyl ester(GMA) by soap-free polymerization. Synthetic conditions of magnetic microspheres: surface modification of reactive NaUA- Fe3O4 magnetic liquid 25 mL, St:GMA = 3.5(mass ratio), reaction temperature 85 ℃, reaction time is 6 h. FT-IR, XRD test shows that the successful synthesis of Fe3O4/P(St-GMA-NaUA) composite polymer magnetic microspheres. TEM images show Fe3O4/P(St-GMA-NaUA) magnetic microsphere has obvious core-shell structure, the thickness of the shell is thin, magnetic content is higher. TG test results show that the magnetic content is 25.3%.The maximum saturation magnetization of magnetic polymer microspheres is 25.23 emu/g, hysteresis loop has no hysteresis phenomenon.3. GO was synthesised by the improved Hummer’s method, and then GO was modified by surfactant DNS-86, and then using chemical coprecipitation synthesis of magnetic Fe3O4-graphene composites. FT-IR, XRD test show the successful synthesis of graphene oxide, its surface contains large amounts of oxygen containing groups and is hydrophilic, then the Fe3O4-graphene composites can be evenly dispersed in aqueous solution; Fe3O4 was coated to the surface of graphene Successfully, with large amounts of epoxy groups Fe3O4-graphene composites is hydrophilic. TEM images show the synthesis of graphene oxide with single-layer structure, Fe3O4 on the surface of graphene can be spread evenly, it improve the whole the specific surface area of composite materials, functional group density, also enhanced composite magnetic responsiveness.4. A novel electro-magnetically composite membrane was prepared by coating Fe3O4/GNS/MPCE magnetic polymer composite emulsion on the surface of working electrode. AA or DA can be rapidly adsorbed from modified electrode The electrochemical current response was investigated by cyclic voltammetry(CV) and study the determination of optimum conditions. Under optimal conditions, scan rates 100 mv.s-1, the pH of PBS was 6.5, the modified electrode exhibited a good response of AA concention from 1×10-6 to 1.4×10-4 mol/L with a detection limit of 0.805 μmol/L. With scan rates 100 mv.s-1, PBS pH = 7, the DA detection limit is 0.086 μmol/L in the linear range of 1×10-6 mol/L to 1.4×10-4 mol/L. AA or DA can be conveniently, rapidly and effectively detected by modified electrode.