An orange-reflecting photonic polymer film has been fabricated based on a hydrogen-bonded cholesteric liquid
crystalline (CLC) polymer consisting of non-reactive (R)-(+)-3-methyladipic acid as the chiral dopant. This polymer film
can be patterned easily by evaporating the chiral dopant at specific locations with a hot pen or a laser beam. Removal of
chiral dopant leads to a decrease in the helical pitch at the heat treated areas leading to a change in color from orange to
green revealing a high contrast pattern. The photonic patterns are irreversible and stable at ambient conditions. This
makes such a CLC polymer film interesting as writable photonic paper.
In this work, we present patterned water-responsive coatings, which alter both their topological and optical properties. The polymer coatings are based on a hydrogen-bonded cholesteric liquid crystalline polymer network. A two-step photopolymerization procedure leads to a patterned coating with repeating liquid crystalline and isotropic areas. The cholesteric liquid crystalline areas reflect green light, whilst the isotropic areas are transparent for visible light. Treatment with alkaline solution results in a hygroscopic polymer salt coating. When placed in demineralized water, the polymer films swells, leading to an enhancement of the surface topography structure in which the liquid crystalline areas swell more. Moreover, the pitch of the helical organization in the cholesteric areas increases due to this swelling leading to a color change from green to red.