A photochromic compound is provided, which may be a pyran, an oxazine, or a fulgide. The photochromic compound has at least one substituent Q attached thereto, each Q independently being N.sub.3, CN, COOR, CCR, C(R)C(R)R, OCOR, OCOOR, SR, OSO.sub.2R, and/or CON(R)R, wherein each R is hydrogen, an unsubstituted or substituted alkyl group having from 1 to 18 carbon atoms; an unsubstituted or substituted aryl group, an unsubstituted or substituted alkene or alkyne group having from 2 to 18 carbon atoms, wherein the substituents are halo or hydroxyl and R is CF.sub.3 or a perfluorinated alkyl group having from 2 to 18 carbon atoms The number, locations and nature of the constituents Q are dependent upon the structure of the photochromic compound.

A photochromic compound is provided, which may be a pyran, an oxazine, or a fulgide. The photochromic compound has at least one substituent Q attached thereto, each Q independently being N.sub.3, CN, COOR, CCR, C(R)C(R)R, OCOR, OCOOR, SR, OSO.sub.2R, and/or CON(R)R, wherein each R is hydrogen, an unsubstituted or substituted alkyl group having from 1 to 18 carbon atoms; an unsubstituted or substituted aryl group, an unsubstituted or substituted alkene or alkyne group having from 2 to 18 carbon atoms, wherein the substituents are halo or hydroxyl and R is CF.sub.3 or a perfluorinated alkyl group having from 2 to 18 carbon atoms The number, locations and nature of the constituents Q are dependent upon the structure of the photochromic compound.

A photochromic compound is provided, which may be a pyran, an oxazine, or a fulgide. The photochromic compound has at least one substituent Q attached thereto, each Q independently being N.sub.3, CN, COOR, CCR, C(R)C(R)R, OCOR, OCOOR, SR, OSO.sub.2R, and/or CON(R)R, wherein each R is hydrogen, an unsubstituted or substituted alkyl group having from 1 to 18 carbon atoms; an unsubstituted or substituted aryl group, an unsubstituted or substituted alkene or alkyne group having from 2 to 18 carbon atoms, wherein the substituents are halo or hydroxyl and R is CF.sub.3 or a perfluorinated alkyl group having from 2 to 18 carbon atoms The number, locations and nature of the constituents Q are dependent upon the structure of the photochromic compound.

A photochromic compound is provided, which may be a pyran, an oxazine, or a fulgide. The photochromic compound has at least one substituent Q attached thereto, each Q independently being N.sub.3, CN, COOR, CCR, C(R)C(R)R, OCOR, OCOOR, SR, OSO.sub.2R, and/or CON(R)R, wherein each R is hydrogen, an unsubstituted or substituted alkyl group having from 1 to 18 carbon atoms; an unsubstituted or substituted aryl group, an unsubstituted or substituted alkene or alkyne group having from 2 to 18 carbon atoms, wherein the substituents are halo or hydroxyl and R is CF.sub.3 or a perfluorinated alkyl group having from 2 to 18 carbon atoms The number, locations and nature of the constituents Q are dependent upon the structure of the photochromic compound.

A photochromic compound is provided, which may be a pyran, an oxazine, or a fulgide. The photochromic compound has at least one substituent Q attached thereto, each Q independently being N.sub.3, CN, COOR, CCR, C(R)C(R)R, OCOR, OCOOR, SR, OSO.sub.2R, and/or CON(R)R, wherein each R is hydrogen, an unsubstituted or substituted alkyl group having from 1 to 18 carbon atoms; an unsubstituted or substituted aryl group, an unsubstituted or substituted alkene or alkyne group having from 2 to 18 carbon atoms, wherein the substituents are halo or hydroxyl and R is CF.sub.3 or a perfluorinated alkyl group having from 2 to 18 carbon atoms The number, locations and nature of the constituents Q are dependent upon the structure of the photochromic compound.

An X-ray-sensitive film includes an acid-hydrolyzed palm mesocarp, a starch, a cellulose, a synthetic polymer, a plant hydrogel, a cyanoacrylate adhesive, glycerin, and an x-ray-sensitive dye. A method of preparing the X-ray-sensitive film includes 32.5 to 45 wt % cellulose based on a total weight of the X-ray-sensitive film, a tensile modulus of 0.75 to 2.5 GPa, a tensile strength of 75 to 125 MPa/kg.Math.m.sup.3, a water absorption of 0.00 to 0.16% measured according to ASTM D570, a carbonate content of 100 to 200 ppm, and shows no cracks when tested according to ASTM D5419.

An X-ray-sensitive film includes an acid-hydrolyzed palm mesocarp, a starch, a cellulose, a synthetic polymer, a plant hydrogel, a cyanoacrylate adhesive, glycerin, and an x-ray-sensitive dye. A method of preparing the X-ray-sensitive film includes 32.5 to 45 wt % cellulose based on a total weight of the X-ray-sensitive film, a tensile modulus of 0.75 to 2.5 GPa, a tensile strength of 75 to 125 MPa/kg.Math.m.sup.3, a water absorption of 0.00 to 0.16% measured according to ASTM D570, a carbonate content of 100 to 200 ppm, and shows no cracks when tested according to ASTM D5419.

A multilayer photochromic article can include a photochromic substrate, which may include a first photochromic layer defining a surface of the substrate, and a second photochromic layer positioned between the surface of the photochromic substrate and a source of actinic radiation, and in which the photochromic substrate and the second photochromic layer are selected such that the fade half-life of the photochromic substrate or the half-life of the first photochromic layer defining the surface of the substrate are greater than the fade half-life of the second photochromic layer.

A multilayer photochromic article can include a photochromic substrate, which may include a first photochromic layer defining a surface of the substrate, and a second photochromic layer positioned between the surface of the photochromic substrate and a source of actinic radiation, and in which the photochromic substrate and the second photochromic layer are selected such that the fade half-life of the photochromic substrate or the half-life of the first photochromic layer defining the surface of the substrate are greater than the fade half-life of the second photochromic layer.

A method of forming an image on a substrate by applying energy, involves a substrate in or on which there are at least two different colour-change agents, i.e. a first colour-change agent capable of giving rise to at least two different colours; and a second colour-change agent capable of giving rise to at least one different colour than achievable with the first colour change agent. A preferred embodiment of the invention is a multi-layer laminate comprising, in order, a layer comprising the first agent, a barrier layer, and a layer comprising the second agent.