System and Method For Encapsulating Photonic Nanocrystals for Dynamic and Responsive Color Media

Abstract

A method and system are disclosed for generating a dynamic and responsive color media. The method includes encapsulating nanomaterials within a capsule to form encapsulated photonic crystals; and dispersing the encapsulated photonic crystals within a film or substrate, wherein the encapsulated nanomaterials retain a liquid dispersion state and can move freely within the capsule and the capsules containing photonic crystals remain stationary within the film or substrate.

Claims

1. A method for generating a dynamic and responsive color media, the method comprising: encapsulating nanomaterials within a capsule to form encapsulated photonic crystals; and dispersing the encapsulated photonic crystals within a film or substrate, wherein the encapsulated nanomaterials retain a liquid dispersion state and can move freely within the capsule and the capsules containing photonic crystals remain stationary within the film or substrate.

2. The method according to claim 1, further comprising: applying an external energy source to the encapsulated photonic crystals to form one or more colors.

3. The method according to claim 1, wherein the film or substrate is a coating for location sensing or a reflective display.

4. The method according to claim 1, wherein the film or substrate is a boundary of an athletic court, the method further comprising: changing a color of the boundary by exposing the film or substrate to a ball having an external energy source.

5. The method according to claim 4, wherein the nanomaterials exhibit a localized, transient color change when exposed to the external energy source.

6. The method according to claim 1, wherein the photonic crystals are pea-pod structure chains of Fe.sub.3O.sub.4 nanoclusters coated by silica exhibiting a predetermined color when aligned based on a size and separation distance of Fe.sub.3O.sub.4 clusters within individual chains.

7. The method according to claim 6, comprising: functionalizing the silica surface of the Fe.sub.3O.sub.4@SiO.sub.2 photonic crystals with octadecyltrimethoxysilane (ODTMS)

8. The method according to claim 1, wherein walls of the capsule are urea-formaldehyde.

9. The method according to claim 1, further comprising: incorporating a colored dye inside the capsule comprising the photonic crystals to change a color of the photonic crystal in an equilibrium state.

10. The method according to claim 1, further comprising: incorporating a colored dye inside the film or substrate to change a color of the photonic crystal in an equilibrium state.

11. The method according to claim 1, comprising: a first state of equilibrium of the encapsulated photonic crystal having a random orientation of the photonic crystals exhibiting no diffraction; and a second state of equilibrium of the encapsulated photonic crystals in the presence of a magnetic field, the photonic crystals align parallel to the field and diffract light, exhibiting a color dependent on the magnetite nanoparticle spacing and size within the chains.

12. The method according to claim 1, wherein the film or substrate film or substrate is a film-forming solution, thermoplastic material, and/or a fiber or elastomer.

13. The method according to claim 12, wherein the film-forming solution is a water-based paint or polymer.

14. A method for generating a dynamic and responsive color media, the method comprising: dispersing a photonic material in a solvent, the photonic crystals being encapsulated in a material shell forming microcapsules, the material shell acting a as a barrier, which protects the photonic material-solvent dispersion from phase mechanics and an exterior environment; mixing the photonic material-solvent dispersion with a film-former or substrate; and applying the photonic material-solvent dispersion with the film-former or substrate to an object and drying or curing the photonic material-solvent dispersion with the film-former or substrate to seal the photonic material in a hardened film or substrate.

15. The method according to claim 14, further comprising: preserving the encapsulated dispersion of photonic materials to allow for the dynamic responsive and tunable color properties of the photonic materials.

16. The method according to claim 14, comprising: tuning the behavior of the photonic materials to include one or more of the following: response and relaxation time, color and color range, and stimuli specificity.

17. The method according to claim 14, comprising: manipulating the photonic materials with an external stimulus, and wherein the external stimulus is a magnetic field or an electric field.

18. A system for generating a dynamic and responsive color media, the film or substrate comprising: nanomaterials encapsulated within a capsule to form encapsulated photonic crystals; and wherein the encapsulated photonic crystals are dispersed within a film or substrate, and wherein the encapsulated nanomaterials retain a liquid dispersion state and can move freely within the capsule and the capsules containing photonic crystals remain stationary within the film or substrate.

19. The system according to claim 18, comprising: applying an external energy source to the encapsulated photonic crystals to form one or more colors.

20. The system according to claim 18, wherein the film or substrate is a coating for location sensing or a reflective display.

21. The system according to claim 18, wherein the film or substrate is a boundary of a tennis court, and wherein a color of the boundary is changed by exposing the film or substrate to a ball having an external energy source.

22. The system according to claim 21, wherein the nanomaterials exhibit a localized, transient color change when exposed to the external energy source.

23. The system according to claim 1, wherein the photonic crystals are pea-pod structure chains of Fe.sub.3O.sub.4 nanoclusters coated by silica exhibiting a predetermined color when aligned based on a size and separation distance of Fe.sub.3O.sub.4 clusters within individual chains.

24. The system according to claim 23, wherein the silica surface of the Fe.sub.3O.sub.4@SiO.sub.2 photonic crystals is functionalized with octadecyltrimethoxysilane (ODTMS)

25. The system according to claim 18, wherein walls of the capsule are urea-formaldehyde.

26. The system according to claim 18, further comprising: a colored dye incorporated inside the capsule comprising the photonic crystals to change a color of the photonic crystal in an equilibrium state.

27. The system according to claim 18, further comprising: a colored dye incorporated inside the film or substrate to change a color of the photonic crystal in an equilibrium state.

28. The system according to claim 18, comprising: a first state of equilibrium of the encapsulated photonic crystal having a random orientation of the photonic crystals exhibiting no diffraction; and a second state of equilibrium of the encapsulated photonic crystals in the presence of a magnetic field, the photonic crystals align parallel to the field and diffract light, exhibiting a color dependent on the magnetite nanoparticle spacing and size within the chains.

29. The system according to claim 18, wherein the film or substrate film or substrate is a film-forming solution, thermoplastic material, and/or a fiber or elastomer.

30. The system according to claim 29, wherein the film-forming solution is a water-based paint or polymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0016] FIG. 1A is an illustration of an equilibrium OFF state having a random orientation of photonic crystals exhibiting no diffraction.

[0017] FIG. 1B is an illustration of the orientation of photonic crystals in the presence of a magnetic field, the photonic crystal chains align parallel to the field and diffract light, exhibiting a color dependent on the magnetite nanoparticle spacing and size of the photonic crystals within the chains in accordance with an exemplary embodiment.

[0018] FIG. 2 is an illustration of red photonic crystal chains with a blue dye to improve contrast in accordance with an exemplary embodiment.

[0019] FIG. 3 is an illustration of films in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

[0020] Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

[0021] The present disclosure relates to systems and methods to produce and use encapsulated photonic crystals in solid films and or substrates. Such films and substrates containing capsules of photonic crystals can be employed where dynamic, responsive, or tunable color properties are desired. For example, but not limited to, color changing films for personal customization, coatings for location sensing such as in sports where a ball landed in relation to a boundary, or for reflective displays such as chemical free marking boards or full color range electronic ink screens.

[0022] In accordance with an exemplary embodiment, photonic crystals dispersed in a solvent are encapsulated in a material shell which acts as a barrier and protects the material-solvent dispersion from the solid phase mechanics and exterior environment. Microcapsules may be mixed with a range of film-formers or substrates, which can then be applied to an object if desired and dried or cured, trapping and further sealing the microcapsules in the hardened film or substrate.

[0023] In accordance with an exemplary embodiment, the encapsulated liquid dispersion of photonic crystals can be preserved allowing for the dynamic responsive and tunable color properties of the photonic crystals. Photonic crystals can be manipulated by an external stimulus which is defined as any force capable of activation of the photonic crystals (for example, magnetic or electric fields). The composition of the internal phase can vary widely for the purpose of tuning the behavior of the photonic nanomaterials including but not limited to response and relaxation time, color and color range, and stimuli specificity. Physical properties which have an effect on the behavior of photonic crystals may include viscosity, conductivity, refractive index, and polarity.

[0024] In accordance with an exemplary embodiment, the nanomaterials can be, for example, pea-pod structure chains of Fe.sub.3O.sub.4 nanoclusters coated by silica exhibiting a predetermined color when aligned based on the size and separation distance of Fe.sub.3O.sub.4 clusters within individual chains. (See, for example, Yin et al. J. Mater. Chem. C, 2013, 1, 6151, which is incorporated herein by reference in its entirety). These 1D photonic crystal chains can be turned ON and OFF by manipulating their orientation using an external energy source. When these chains are encapsulated and sealed into a solid film or substrate, the resulting material has sensing properties such that it can detect the presence of an energy source by exhibiting a localized, transient color change.

[0025] FIGS. 1A and 1B show the schematic representation of the diffraction of light off the surface of a film having encapsulated photonic crystal chains in both the equilibrium OFF state and the ON state in the presence of a magnetic field. FIG. 1A is an illustration of the equilibrium off state having a random orientation of photonic crystal chains exhibiting no diffraction. As shown in FIG. 1B, in the presence of an external source, for example, a magnetic field, the photonic crystal chains align parallel to the field and diffract light, exhibiting a color dependent on the magnetite nanoparticle spacing and size within the chains.

[0026] Depending on the selected viscosity and dispersant composition of the internal phase within the capsules, the localized color change may be permanent or recover to its equilibrium OFF state after some time, for example, seconds, minutes, or hours.

[0027] In accordance with an exemplary embodiment, the color of the equilibrium state of the encapsulated slurry/paint film may be adjusted by incorporation of dyes inside the photonic crystal chain's silica layer, the capsule, or the film-forming substrate. Adjustments to the equilibrium state color may also serve as a method of improving the contrast ratio between a localized on state and the surrounding off state colors. FIG. 2 shows capsules with dyes to improve contrast of the photonic crystal chains.

[0028] In accordance with an exemplary embodiment, the realized capsule slurry can be readily mixed with substrate precursors to impart the dynamic color property of the capsules to the substrate in question. Examples of substrate precursors can include film-forming solutions including water-based paints or drying polymers, curing substrates such as radical induced polymerization or heat treated thermoplastics, or incorporated into industrial production of materials such as fibers or elastomers. In accordance with an exemplary embodiment, the paint can be a water-based paint, for example, an acrylic paint.

[0029] In accordance with an exemplary, the disclosure can be used as a marking paint. For example, in sports, a playing surface may be coated with a paint incorporating the capsules. The playing surface may then behave as a sensor, marking the location where contact by a specialized playing object (for example, a ball) has occurred, and then disappearing after a selected time interval. FIG. 3 shows photographs of samples of the dried marking paints with the visible marks. For example, since tennis can be a sport riddled with controversy involving boundary calls, tennis is one of the many sports that stands to benefit directly from this product. Other markets can also benefit from this technology such as drawing boards which are free from chemicals having a magnetic pen which never runs out of ink or degas solvents into the local environment.

Methods

[0030] Encapsulation procedures:

EXAMPLE 1

[0031] Non-polar core phase:

[0032] Silica surface of Fe.sub.3O.sub.4@SiO.sub.2 photonic crystals are functionalized with octadecyltrimethoxysilane (ODTMS) by dispersing in a mixture of 12.5 mL ethanol and 0.5 mL 28-30% ammonium hydroxide solution in a sealed glass vial. 150 L ODTMS is added while stirring and the temperature is raised to a reflux for 1.5 hours (hrs) with occasional sonication. The hydrophobic phonic crystals (HPCs) are magnetically separated and washed with hexanes. The HPCs are then dispersed in 1 mL of a surfactant mixture containing 9 wt % ashless dispersant (RB-ADS-1000) in light paraffin oil.

[0033] A pigment or dye can be added at this time to the core phase to modify the equilibrium state color as desired.

[0034] Encapsulation of core-phase by urea-formaldehyde capsules:

[0035] Dissolve 0.083 g resorcinol and 0.833 g urea into 25 mL 3.33 wt % poly(ethylene-alt-maleic anhydride) in water. Once dissolved, the solution is titrated to pH 3.35 by the addition of a 6 M sodium hydroxide solution. Under mechanical stirring at 450 rpm, 4 mL of the core phase solution is added and the mixture is allowed to emulsify for 10 minutes. Then, 2.27 mL of a 37% formaldehyde solution is added and the solution brought up to 55 C. over 60 minutes and held there for an additional 3 hours. The solution becomes white-turbid as urea-formaldehyde nanoparticles form and the urea-formaldehyde shells grow. Once the reaction is complete, the solution is diluted with water and the capsules are separated and washed several times with water until the microcapsule slurry is free of UF nanoparticles and excess surfactants.

[0036] The microcapsule slurry is concentrated and ready to be mixed with film forming material or solution as desired.

[0037] Photonic crystals have the potential to disrupt or at the very least support the traditional dyes and pigments industry. Dyes and pigments have inherent limitations as they undergo physical process to produce color which is susceptible to bleaching and the color will fade over time. Photonic crystals improve the lifetime of colors as the physical mechanism by which they produce color is fundamentally different and relies on light diffraction rather than light absorption. This diffraction mechanism is not susceptible to bleaching and therefore can drastically improve lifetime of colors and reduce fading. Furthermore, the photonic crystals possess unique color properties such that one material can be made to produce any number of colors across the light spectrum, which is not the case of dyes and pigments having specific colors and which must be mixed with each other to create additional colors. Some photonic crystals may be a disordered array of materials providing a flat color from all viewing angles or highly crystalline in nature and having colors dependent on the viewing angle. The latter, angular dependency allows for these crystals to be manipulated to tune and react to their environment and become a type of sensor. As described here, photonic crystals can be switched between an equilibrium OFF state and a bright colored ON state by rotating the crystals within the capsules using a magnetic field.

[0038] Encapsulation of materials or liquids is prevalent in industry and will continue to be for the foreseeable future. In accordance with an exemplary embodiment, the technique allows for controlled separation of two phases of liquids in order to accomplish some process or integration of materials which may not be readily combined. Prior art utilizing photonic crystals has employed encapsulation techniques in order to create photonic crystal spheres of a fixed color, or storage compartments for photonic crystal components/monomers, but not to preserve the suspended liquid state of photonic crystals so that they may remain active in a solid substrate, which is precisely what is demonstrated herein.

[0039] In accordance with an exemplary embodiment, a magnetic field responsive coating is disclosed that can include, for example, a single type of photonic crystal, nanochains, and having a range of fixed colors.

[0040] As used herein, an element or step recited in the singular and preceded by the word a or an should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to example embodiment or one embodiment of the present disclosure are not intended to be interpreted as excluding the existence of additional examples that also incorporate the recited features.

[0041] The patent claims at the end of this document are not intended to be construed under 35 U.S.C. 112(f) unless traditional means-plus-function language is expressly recited, such as means for or step for language being expressly recited in the claim(s).

[0042] It will be apparent to those skilled in the art that various modifications and variation can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.