Method of creating colored materials by fixing ordered structures of magnetite nanoparticles within a solid media

Abstract

Compositions and methods wherein ordered structures of photonic nanocrystals are created in a liquid medium and then such structures are fixed by converting the liquid medium to a solid. In addition, compositions and methods of reversibly fixing such structures, so that ordered structures can be reversibly created in a liquid medium, converted to solid, and then converted back to liquid, wherein new ordered structures can be created and again fixed.

1 . A method of creating colored materials, comprising:
 fixing ordered structures of magnetically responsive nanoparticles within a media, such that the ordered structures diffract light to create colors.   
     
     
         2 . The method of  claim 1 , further comprising creating the ordered structures of magnetically responsive nanoparticles with an external magnetic field. 
     
     
         3 . The method of  claim 2 , wherein the ordered structures of magnetically responsive nanoparticles are created in a liquid media and the ordered structures are fixed by converting the liquid media to a solid media. 
     
     
         4 . The method of  claim 3 , wherein the liquid media is a photocurable solution. 
     
     
         5 . The method of  claim 4 , further comprising fixing the ordered structures of magnetically responsive nanoparticles with an UV source having a wavelength of approximately 240 nm to approximately 365 nm. 
     
     
         6 . The method of  claim 1 , wherein the ordered structures are created in a reversible media, wherein the reversible media is reversible from a solid to a liquid, such that the color can be changed. 
     
     
         7 . A method of generating multicolored patterns comprising:
 fixing a structural color from a superparamagnetic colloidal nanocrystal clusters (CNC); and   introducing a high resolution patterning of multiple structural colors using a single material.   
     
     
         8 . The method of  claim 7 , further comprising repetitive tuning and fixing of the structural color from a mixture of superparamagnetic photonic crystals and photocurable resin. 
     
     
         9 . The method of  claim 7 , wherein the superparamagnetic photonic crystals consists of a plurality of domain magnetite nanoparticles, which are coated. 
     
     
         10 . The method of  claim 7 , further comprising adding an external magnetic field to the photonic crystals, and wherein the external magnetic field assembles the photonic crystals in a chain-like structures along the magnetic field lines. 
     
     
         11 . The method of  claim 7 , wherein the attractive magnetic force due to the superparamagnetic core is balanced with repulsive solvation force, both of which determine the inter-particle distance under any given magnetic field strength. 
     
     
         12 . The method of  claim 7 , wherein the inter-particle distance in a chain determines the color of the light diffracted from the chain. 
     
     
         13 . The method of  claim 7 , wherein the color can be tuned by simply varying the inter-particle distance using external magnetic fields. 
     
     
         14 . The method of  claim 7 , wherein once the desired color is obtained, the desired color is fixed by solidifying the photocurable resin through UV exposure. 
     
     
         15 . The method of  claim 7 , wherein the particle chains are frozen in the solidified polymer network without distorting its periodic arrangements, thus retaining the structural color. 
     
     
         16 . The method of  claim 7 , further comprising adding a hydrogen bonding solvent, which forms a solvation layer around the particle surface, and which provides a strong repulsion when two solvation layers overlap. 
     
     
         17 . The method of  claim 16 , wherein the hydrogen bonding solvent is an alkanol. 
     
     
         18 . The method of  claim 17 , further comprising adding ethanol to the system. 
     
     
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         31 . A method of forming magnetochromatic microspheres comprising:
 coating a plurality of magnetite nanocrystals with a surface medium;   dispersing the plurality of coated magnetite nanocrystals in a curable solution;   placing the magnetite nanocrystals and curable solution in an immiscible solution to form an emulsion;   exposing the emulsion to an external magnetic field, which aligns the coated magnetite nanocrystals in one-dimensional chains within emulsion droplets within the curable solution; and   curing the emulsion droplets within the curable solution into magnetochromatic microspheres.   
     
     
         32 . The method of  claim 31 , wherein the step of curing the emulsion droplets is by exposing the curable solution to a UV illumination source. 
     
     
         33 . The method of  claim 32 , wherein the step of exposing the curable solution to the UV illumination source fixes the ordered structures within the microspheres. 
     
     
         34 . The method of  claim 31 , wherein the plurality of magnetite nanocrystals have a chemical composition of γ-Fe 2 O 3 Fe 2 O 3  and/or Fe 3 O 4 . 
     
     
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         39 . The method of  claim 31 , further comprising microspheres immersed in a phase-changeable matrix, the phase-changeable matrix having a liquid phase and a solid phase. 
     
     
         40 . The method of  claim 39 , wherein when the matrix is the liquid phase, adjusting an angle of the external magnetic field to change an orientation of the microspheres. 
     
     
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         47 . The method of  claim 31 , wherein the immiscible liquid is a viscous non-polar solvent, mineral oil and/or silicone oil and/or paraffin oil. 
     
     
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         52 . The method of  claim 39 , wherein the phase-changeable matrix is a polyethylene glycol (PEG) film, paraffin, long-chain alkanes, esters, primary alcohols and/or a non-crosslinked polymers such as polyethylene, poly(ethylene oxide), polyethylene-block-poly(ethylene glycol) and/or polyesters. 
     
     
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         59 . A method of forming magnetochromatic microspheres comprising:
 a simultaneous magnetic assembly and UV curing process of an emulsion system comprised of superparamagnetic Fe 3 O 4 @SiO 2  colloidal particles, which are self-organized into ordered structures inside emulsion droplets of UV curable resin.   
     
     
         60 . The method of  claim 59 , wherein the ordered structures are fixed by an immediate UV curing process to polymerize the droplets. 
     
     
         61 . The method of  claim 59 , further comprising rotating the microspheres using an external magnetic field to change the orientation of the magnetic chains and thereby the diffractive colors of the microspheres. 
     
     
         62 . A display comprising:
 microspheres containing ordered structures of photonic crystals, which are rotated, which changes the angle of diffraction of light passing through the microspheres.   
     
     
         63 . The display of  claim 62 , further comprising rotating the microspheres, which changes the angle of diffraction of light passing through the microspheres, which changes a first color to a second color. 
     
     
         64 . The display of  claim 62 , further comprising microspheres immersed in a phase-changeable matrix, the phase-changeable matrix having a liquid phase and a solid phase. 
     
     
         65 . The display of  claim 64 , wherein when the matrix is the liquid phase, adjusting an angle of the external magnetic field to change an orientation of the microspheres. 
     
     
         66 . The display of  claim 65 , wherein the orientation of the microspheres are fixed when the matrix goes to the solid phase. 
     
     
         67 . The display of  claim 62 , wherein the field strength required to rotate the microspheres is dependent on an amount magnetite nanocrystals in each of the microspheres. 
     
     
         68 . The display of  claim 64 , wherein the phase-changeable matrix is a polyethylene glycol (PEG) film. 
     
     
         69 . The display of  claim 64 , wherein the phase-changeable matrix is paraffin, long-chain alkanes, esters, primary alcohols and/or a non-crosslinked polymers such as polyethylene, poly(ethylene oxide), polyethylene-block-poly(ethylene glycol) and/or polyesters.