Maghemite nanoparticles

Thiinemann AF, Schiitt D, Kaufher L, Pison U, Mdhwald H (2006) Maghemite nanoparticles protectively coated with poly(ethylene imine) and poly(ethylene oxide)-Wocl -poly(glutamic acid). Langmuir 22 2351-2357... 

Hu L, Hach D, Chaumont D, Brachais C-H, Couvercelle J-P, Percheron A (2009) Comparison of various methods of grafting of modified-PEG onto maghemite nanoparticles in aqueous medium including synthesis by microwave refluxing. J Sol-Gel Sci Technol 49 277-284... 

Held et al. [65] earUer reported that monodisperse, highly crystalhne maghemite nanoparticles in organic solvents could be transferred into an aqueous medium using tetramethylammonium hydroxide and stabiUsed at... 

Fig. 15 TEM images of clusters of maghemite nanoparticles deposited from dispersions in water in the presence of PELLysioo-fc-PAspso. Reprinted with permission from [65], copyright (2003) American Chemical Society...

Lucas, LT. et al., Surface charge density of maghemite nanoparticles Role of electrostatics in the proton exchange, J. Phys. Chem. C. Ill, 18568, 2007. 

Figure 1. TEM image of maghemite nanoparticles covered with the oleic acid dispersed in toluene.

Figure 2. Excess magnetization A/w of the liquid-crystal compound mixed with maghemite nanoparticles of 17 nm. For clarity, the Am data obtained during the heating (open circles) and cooling (open triangles) runs were shifted by 0.035 10 emu and 0.025 10 emu, respectively. x = 0.10.

A single-pot reaction of maghemite nanoparticles, fluorescent pigment, polyester resin, TweenSO, SpanSO, AIBN, and styrene dispersed in an aqueous NaOH solution, led to the formation of ferromagnetic (hysteresis in vibrating sample magnetometry analysis) hybrid nanoparticles [164]. Magnetite compatibilization is ascribed to the application of polyester resin. 

Figure 11 TEM image of maghemite nanoparticles deposited from a dispersion in water and the corresponding XRD pattern (red trace). The blue, sharper XRD pattern is obtained from the same nanoparticles dispersed in hexane, which prodnced a more ordered array of maghemite. (Reproduced with permission from Ref. 35. American Chemical Society, 2003.)...

Recently, polymer nanocomposites have attracted an increased attention, where nanotechnology is applied to produce materials with remarkable improvements in properties and performance. The most popular approach to produce this new family of composite materials is to introduce nanoscale particles into a polymer matrix to produce polymer/nano-particle composites. Examples of such nanoparticles include layered silicates, layered titanates, carbon nanotubes (CNTs), gold, silver, and maghemite nanoparticles, and fluorine mica [79, 80]. 

MAGNETIC RESINS PRODUCTION Maghemite Nanoparticles Production... 

Figure 4. (a) Maghemite nanoparticles in the presence and (b) absence of the magnetic field. 

Figure 6. (a) The AFM micrograph of the maghemite nanoparticles (b) and probability density function (PDF) of diameters of maghemite. 

To prepare the composite, each one of the obtained alkyd resin was milled and fused. Afterwards, maghemite nanoparticles were mixed with the resin to obtain a composite containing 5 wt% of maghemite. This proceeding is schematically shown in Figure 14. 

Figure 14. Schematic proceeding to obtain the magnetic composite containing 5 wt% of maghemite nanoparticles.

Figure 8. Diffractograms of the maghemite nanoparticles, bioresins (PU1-PU4) and nanocomposite (PUS) samples.

Figure 9 shows the SAXS analysis of the maghemite nanoparticles inside the biofoam matrix. The Figure detail shows the Gaussian deconvolution of the SAXS data. This Gaussian deconvolution allowed several calculations, of which main results are shown in Table 4. These SAXS results showed two main kinds of scattering centers. These centers are related to superstructures, which present diameters equal to 60 and 38 nm, spaced from each other by 23 and 15 nm, respectively. 

Figure 9. SAXS analysis of the maghemite nanoparticles inside the biofoam matrix (the detail of the figure show the Gaussian deconvolution).

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