Photonic crystal micropatterns and anti-counterfeiting films, methods of making, and methods of use

A chromogenic sensor having a hidden anti-counterfeiting pattern comprising:

• a porous polymer material comprising an ordered array of voids separated by a polymer framework,
• wherein the porous polymer material has a first region having the hidden anti-counterfeiting pattern and a second region;
• wherein the first region of the porous polymer material has a deformed state and a recovered state,
• wherein when the first region is in the deformed state, the voids are collapsed and the first region has a characteristic of being transparent, wherein when the first region is in the recovered state, the voids are uncollapsed and the first region has a characteristic of having an iridescent color;
• wherein the second region has been exposed to a programming step, thereby causing the voids of the second region to irreversibly remain in a collapsed state and wherein the second region has a characteristic of remaining transparent;
• wherein the hidden anti-counterfeiting pattern is not visible when the first region is in a deformed state since both the first and second regions have the characteristic of being transparent;
• and
• wherein when the first region is in a deformed state, contacting the chromogenic sensor with a trigger solvent causes the first region of the porous polymer material to be in the recovery state thereby revealing the anti-counterfeiting pattern.