Photonic polymer multilayers for colorimetric radiation sensing

1. A radiation sensor comprising,

a substrate;

a polymer multilayer film comprising alternating layers of a high refractive index polymer and a low refractive index polymer;

wherein the high refractive index polymer comprises repeat units derived from a first photo-crosslinkable monomer; and

wherein the low refractive index polymer consists of repeat units derived from a second photo-crosslinkable monomer and at least one monomer selected from the group consisting of C 1-12 alkyl (meth)acrylates, C 1-12 aryl (meth)acrylates, macromeric (meth)acrylates, (meth)acrylic acids, alpha olefins, vinyl esters, vinyl alkyl ethers, styrenic monomers, fluorinated monomers, and combinations thereof.

2. The radiation sensor of claim 1 , wherein the substrate is glass.

3. The radiation sensor of claim 1 , wherein the substrate is a flexible substrate.

4. The radiation sensor of claim 3 , wherein the flexible substrate is a poly(ethylene terephthalate) substrate.

5. The radiation sensor of claim 1 , wherein the polymer multilayer film comprises at least 2 to 50 alternating layers.

6. The radiation sensor of claim 1 , wherein the high refractive index polymer layers and the low refractive index polymer layers each independently have thicknesses of 0.01 to 0.2 micrometers.

7. The radiation sensor of claim 1 , wherein the high refractive index polymer has a refractive index greater than 1.5.

8. The radiation sensor of claim 1 , wherein the high refractive index polymer further comprises repeat units derived from para-methylstyrene.

9. The radiation sensor of claim 1 , wherein the low refractive index polymer has a refractive index less than or equal to 1.5.

10. The radiation sensor of claim 1 , wherein the low refractive index polymer consists of repeat units derived from a photo-crosslinkable monomer and at least one monomer selected from the group consisting of oligoethylene glycol methacrylate, methyl methacrylate, and combinations thereof.

11. The radiation sensor of claim 1 , wherein the first and second photo-crosslinkable monomers each comprise a benzophenone group.

12. The radiation sensor of claim 1 , wherein the high refractive index polymer comprises 1 to 10 mole percent of the first photo-crosslinkable monomer, and the low refractive index polymer comprises 1 to 10 mole percent of the second photo-crosslinkable monomer.

13. The radiation sensor of claim 1 , wherein

the substrate is glass;

the high refractive index polymer comprises repeat units derived from para-methylstyrene and a first photo-crosslinkable monomer;

the low refractive index polymer consists of repeat units derived from a second photo-crosslinkable monomer and at least one monomer selected from the group consisting of oligoethylene glycol methacrylate, methyl methacrylate, and combinations thereof; and

the first and second photo-crosslinkable monomers each comprise a benzophenone group.

14. The radiation sensor of claim 1 , wherein

the support substrate is a flexible support substrate comprising poly(ethylene terephthalate);

the high refractive index polymer comprises repeat units derived from para-methylstyrene and a photo-crosslinkable monomer;

the low refractive index polymer consists of repeat units derived from a photo-crosslinkable monomer and at least one monomer selected from the group consisting of oligoethylene glycol methacrylate, methyl methacrylate, or a combination thereof; and

the first and second photo-crosslinkable monomers each comprise a benzophenone group.

15. The radiation sensor of claim 1 ,

wherein the low refractive index polymer consists of repeat units derived from oligoethylene glycol methacrylate and the second photo-crosslinkable monomer comprising a benzophenone group; and

wherein a 5 to 300 nanometer blue shift in the wavelength of reflected light of an irradiated region of the sensor occurs upon swelling the low refractive index polymer layers following exposure to a dose of ionizing radiation of greater than 0 to 400 kilogray.

16. The radiation sensor of claim 1 ,

wherein the low refractive index polymer consists of repeat units derived from methyl methacrylate and the first photo-crosslinkable monomer comprising a benzophenone group; and

wherein a 5 to 300 nanometer red shift in the wavelength of reflected light of an irradiated region of the sensor occurs upon swelling the low refractive index polymer layers following exposure to a dose of ionizing radiation of greater than 0 to 400 kilogray.

17. An article comprising a radiation sensor, the radiation sensor comprising,

a substrate;

a polymer multilayer film comprising alternating layers of a high refractive index polymer and a low refractive index polymer;

wherein the high refractive index polymer comprises repeat units derived from a first photo-crosslinkable monomer; and

wherein the low refractive index polymer consists of repeat units derived from a second photo-crosslinkable monomer and at least one monomer selected from the group consisting of C 1-12 alkyl (meth)acrylates, C 1-12 aryl (meth)acrylates, macromeric (meth)acrylates, (meth)acrylic acids, alpha olefins, vinyl esters, vinyl alkyl ethers, styrenic monomers, fluorinated monomers, and combinations thereof;

wherein the article is a wearable patch, a packaging material, a label, or a window pane.

18. A method of detecting radiation, the method comprising,

exposing to ionizing radiation a radiation sensor comprising,

a substrate;

a polymer multilayer film comprising alternating layers of a high refractive index polymer and a low refractive index polymer;

wherein the high refractive index polymer comprises repeat units derived from a first photo-crosslinkable monomer; and

wherein the low refractive index polymer consists of repeat units derived from a second photo-crosslinkable monomer and at least one monomer selected from the group consisting of C 1-12 alkyl (meth)acrylates, C 1-12 aryl (meth)acrylates, macromeric (meth)acrylates, (meth)acrylic acids, alpha olefins, vinyl esters, vinyl alkyl ethers, styrenic monomers, fluorinated monomers, and combinations thereof;

immersing the sensor in a solvent to swell the low refractive index layers; and

monitoring the sensor for a change in color resulting from exposure to a dose of ionizing radiation.

19. The method of claim 18 , wherein the dose of ionizing radiation is greater than 0 to 400 kilogray.

20. The method of claim 18 , wherein

the high refractive index polymer comprises repeat units derived from para-methylstyrene and a photo-crosslinkable monomer comprising benzophenone;

the low refractive index polymer comprises repeat units derived from oligoethylene glycol methacrylate, methyl methacrylate, or a combination thereof and a photo-crosslinkable monomer comprising benzophenone;

the solvent comprises ethanol; and

the change in color is a shift in the wavelength of reflected light of about 5 to 300 nanometers.