Magneto dielectric polymer nanocomposites and method of making
In accordance with the present invention, novel superparamagnetic magneto-dielectric polymer nanocomposites are synthesized using a novel process. The tunability of the dielectric/magnetic properties demonstrated by this novel highly-viscous solvent-free polymer nanocomposite that is amenable to building 3D electromagnetic structures/devices by using processes such as 3D printing, compression molding or injection molding, when an external DC magnetic field is applied, exceeds what has been previously reported for magneto-dielectric polymer nanocomposite materials.
1. A method of preparing a superparamagnetic polymer nanocomposite material, the method comprising:
coating single-domain magnetic nanoparticles with surfactants;
dissolving a low-loss polymer and the coated magnetic nanoparticles in a solvent, wherein the solvent has a vaporizing temperature that is lower than the curing temperature of the low-loss polymer;
magnetically stirring the dissolved low-loss polymer and coated magnetic nanoparticles to obtain a dissolved low-loss polymer nanocomposite having substantially uniform dispersion;
heating the dissolved low-loss polymer nanocomposite in a vacuum oven to a temperature that is above the vaporizing temperature of the solvent and below the curing temperature of the low-loss polymer and pulsing the vacuum of the vacuum oven during the heating of the dissolved low-loss polymer nanocomposite to vaporize the dissolved low-loss polymer nanocomposite to remove the solvent, without curing the low-loss polymer nanocomposite, to obtain a solvent-free low-loss polymer nanocomposite; and
curing the solvent-free low-loss polymer nanocomposite obtain a superparamagnetic polymer nanocomposite material.
2. The method of claim 1 , wherein the single-domain magnetic nanoparticles are selected from Fe 3 O 4 nanoparticles and CoFe 2 O 4 nanoparticles.
3. The method of claim 1 , wherein the single-domain magnetic nanoparticles are Fe 3 O 4 nanoparticles having an average size of approximately 8 nm.
4. The method of claim 1 , wherein the single-domain magnetic nanoparticles are CoFe 2 O 4 nanoparticles having an average size of approximately 10 nm.
5. The method of claim 1 , wherein the surfactant is selected from oleylamine and oleic acid.
6. The method of claim 1 , wherein the solvent-free low-loss polymer contains about 25% butadiene resin.
7. The method of claim 1 , wherein the single-domain magnetic nanoparticles comprise a plurality of individual magnetic nanoparticles and wherein coating the magnetic nanoparticles with surfactants further comprises substantially encapsulating and isolating each of the individual magnetic nanoparticles.
8. The method of claim 1 , wherein the vaporizing temperature of the solvent is between about 40° C. and 50° C., under vacuum.
9. The method of claim 1 , wherein the curing temperature of the low-loss polymer is between about 100° C. and 110° C., under vacuum.