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Field-responsive superparamagnetic composite nanofibers and methods of use thereof

a composite nanofiber, field-responsive technology, applied in the field of field-responsive composite nanofibers, can solve the problems of inability to achieve superparamagnetic properties, 100 nm, and inability to produce magnetic composite nanofibers (100 nm),

Inactive Publication Date: 2006-01-26
HATTON T ALAN +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] In one embodiment, this invention provides a superparamagnetic fiber comprising magnetite particles and a polymeric matrix. In one embodiment, the fiber is a nanofiber, which in another embodiment is less than 500 nm in diameter, or in another embodiment, the nanofiber has a diameter that ranges from 10 nm-1 μm.

Problems solved by technology

The relative magnitudes of the stiffness enhancement and fiber deformation by such fibers are expected to increase as the diameter of the embedding polymer fiber is reduced, and therefore, to date, production of magnetic composite nanofibers (i.e. with diameters on the order of 100 nm or less) with superparamagnetic properties, with defined mechanical properties, has not been achieved.

Method used

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  • Field-responsive superparamagnetic composite nanofibers and methods of use thereof
  • Field-responsive superparamagnetic composite nanofibers and methods of use thereof
  • Field-responsive superparamagnetic composite nanofibers and methods of use thereof

Examples

Experimental program
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example 1

Synthesis of Composite Nanofibers Containing Magnetite Nanoparticles

[0099] The size distribution of the magnetite nanoparticles was determined by DLS (FIG. 1), and corresponded to an average hydrodynamic diameter of 25 nm. An analysis of TEM images of the as-synthesized magnetite nanoparticles (FIG. 2) indicated an average core size, assuming a log normal distribution, of 7.5±2.9 nm. Only the magnetite cores were visible in TEM measurements, as the polymer coatings were of low contrast, and could not be discerned in these images. The difference between the average hydrodynamic diameter and core size yielded a thickness of about 9 nm for the polymer shell.

[0100] The dependence of the magnetization, M, of the magnetite fluid on the applied magnetic field in the SQUID tests is shown in FIG. 3. The magnetite nanoparticle suspension exhibited superparamagnetic behavior in that there was zero remnant magnetization at zero applied field. The saturation magnetization was approximately 0.5...

example 3

Electrospinning Effects on Nanofiber Characteristics

[0105] In order to further characterize PEO / magnetite and PVA / magnetite nanofibers, transmission electron microscropy was utilized to visualize the fibers (FIG. 6). The weight percentages of magnetite nanoparticles within the fibers were 28%, and 8% for PEO / magnetite and PVA / magnetite nanofibers, respectively. The relatively large size of the PEO fiber and high content of nanoparticles within the fiber made it difficult to focus the TEM pictures, but the contour of the alignment of the nanoparticles into columns along the fiber axis direction was readily visible. For the PVA / magnetite fiber, the images were clearer, and demonstrated magnetite nanoparticle alignment in columns parallel to the fiber axis direction within the fiber.

[0106] Magnetite nanoparticles can form chains in solution owing to magnetic coupling effects between particles. The number of nanoparticles, n0. in a chain in the fluid, at zero external field, can be es...

example 4

Structural Characterization of the Composite Nanofibers Comprising Magnetite Nanoparticles

[0109] The elastic modulus of the fibers was evaluated using an AFM indentation technique according to the following formula [Vanlandingham M. R., et al., J. Adhesion 1997; 64: 31-57; Sneddon J. N., Int. J. Engng. Sci. 1965; 3: 47-56; Pharr G. M., et al., J. Mater. Res. 1992; 7: 613-617; Vanlandingham M. R., et al., Composites Part A1999; 30:75-83; Drechsler D., et al., Appl. Phys. A 1998; 66: S825-S829]: S=ⅆPⅆΔ⁢ ⁢Zi⁢❘Pmax=2⁢E*⁡(Aπ)12(3)

[0110] Here, S was the slope of the unloading curve at Pmax, P was the applied load, A was the contact area, ΔZi is the indentation depth, and E* was the effective Young's modulus of the contact as defined by 1E*=1-vs2Es+1-vt2Et(4)

[0111] In equation (4), Es and Et were the elastic moduli, and vσ and vt the Poisson ratios of the sample and the tip, respectively. A diamond tip was used, with asymmetric pyramidal geometry; indent size was characterized by the la...

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Abstract

The present invention relates to magnetic field-responsive fibers, which comprise magnetite particles and a polymeric matrix. The invention also provides methods of producing the same, in particular via electrospinning of a stably dispersed or monodispersed polymer solution, either aqueous or organic, comprising the magnetite particles, and applications thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This Application claims the benefit of U.S. Provisional Application No. 60 / 575,423, filed Jun. 1, 2004, which is hereby incorporated it its entirety.GOVERNMENT INTEREST STATEMENT [0002] This invention was made in whole or in part with government support under Contract DAAD-19-02-D0002 awarded by the United States Army through the Institute for Soldier Nanotechnologies, The government may have certain rights in the invention.FIELD OF THE INVENTION [0003] The present invention relates to field-responsive, composite nanofibers, methods of producing the same, and applications thereof. The present invention has wide application in such fields as magnetic filters, sensors, information storage, magnetic shielding, tunable composites, magnetic separation, SMART fabrics and piezomagnetic transducers. BACKGROUND OF THE INVENTION [0004] Magnetic composite fibers, in which magnetic nanoparticles are embedded into a polymeric fiber matrix, can be ex...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D02G3/00D01D5/00D01F1/10D01F6/14D01F6/16D01F8/00
CPCD01D5/0007D01D5/0038Y10T428/2913D01F6/14D01F6/16D01F1/10
Inventor HATTON, T. ALANRUTLEDGE, GREGORY C.SINGH, HARPREETWANG, MAO
Owner HATTON T ALAN
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