Patent ID: 8465887

Claim:
An erasable medium comprising: a substrate, wherein the substrate is selected from the group consisting of paper, glass, ceramic, wood, plastic, fabric, textile, metal, plain paper, coated paper, no tear paper, and mixtures thereof; and a photochromic layer disposed over the substrate, the photochromic layer comprising one or more photochromic polymers dispersed in at least one polymer binder, at least one of the one or more photochromic polymers having the following general formula: wherein x ranges from about 1 to about 10, n ranges from about 1 to about 1000, and m ranges from 1 to about 1000, and the at least one polymer binder having one of the following general formulas: wherein x ranges from about 1 to about 10, n ranges from about 1 to about 1000, and m ranges from 1 to about 1000, and wherein each of the photochromic polymer and the polymer binder has a glass transition temperature in the range of about 30° C. to about 150° C.