Methods and systems for thermal printing of photonic crystal materials, and thermally printable photonic crystal materials and assemblies
Methods and systems for thermal printing of thermally printable photonic crystal materials and assemblies. The photonic crystal materials and assemblies are responsive to thermal stimuli, wherein temperatures above a thermal threshold results in an optically detectable change in the appearance of the materials and assemblies. Heat is selectively applied to one or more portions of the materials and assemblies, in order to thermally print a graphic onto the materials and assemblies.
1. A thermally printable photonic crystal assembly comprising:
a thermally printable photonic crystal material containing voids; and
a substrate attached to the thermally printable photonic crystal material via thermal bonding or lamination;
wherein the assembly is responsive to selective application of heat equal to or above the thermal threshold, such that after the thermal bonding or lamination, when a portion of the photonic crystal assembly and not the remainder of the photonic crystal assembly is exposed to a temperature equal to or above a thermal threshold, a corresponding portion of the material has a collapse or decrease in spacing of its voids which causes an optically detectable change in a reflection peak of the corresponding portion of the material.
2. The assembly of claim 1 further comprising at least one of: an adhesive layer, a top substrate, and a protective cover-sheet.
3. The assembly of claim 1 comprising a thermally insulating top-coat for modulating transfer of heat to the photonic crystal material.
4. The assembly of claim 1 comprising a fixing coating coated on external and internal surfaces of the photonic crystal material, the fixing coating comprises a crosslinking initiator and at least one of a crosslinkable monomer, prepolymer, polymer, and a crosslinking agent.
5. The assembly of claim 1 wherein the assembly is responsive to the selective application of heat to exhibit monochrome, high-contrast graphics.
6. The assembly of claim 1 wherein the assembly is responsive to the selective application of heat to exhibit multi-color graphics.
7. The thermally printable photonic crystal assembly of claim 1 , wherein the voids are an ordered array of voids.
8. The thermally printable photonic crystal assembly of claim 1 comprising periodically repeating layers with different refractive indices.
9. The thermally printable photonic crystal assembly of claim 1 , wherein the detectable change in reflection peak is a change from a peak at a longer wavelength to a peak at a shorter wavelength.
10. The thermally printable photonic crystal assembly of claim 1 , wherein the detectable change in reflection peak is a change in intensity.
11. The thermally printable photonic crystal assembly of claim 1 , wherein the collapse is a partial collapse.
12. The thermally printable photonic crystal assembly of claim 1 wherein the thermally printable photonic crystal material has a first deformation at a first thermal threshold, and a second deformation at a second thermal threshold.
13. The thermally printable photonic crystal assembly of claim 1 comprising wax nanoparticles embedded in the thermally printable photonic crystal material, the wax nanoparticles having a thermal threshold that is different than a polymer material in the thermally printable photonic crystal material.
14. The thermally printable photonic crystal assembly of claim 1 wherein the assembly is responsive to a laser source.
15. The thermally printable photonic crystal assembly of claim 1 wherein the thermally printable photonic crystal material is etched to remove a component having a different thermal threshold than the thermal threshold of the assembly.
16. The thermally printable photonic crystal assembly of claim 1 wherein the substrate is a polymer sheet.