A. Bobrovsky et al., New principle of optical data recording based on reversible transition "selective reflection-absorbance" in photochromic cholesteric copolymers, MOLEC CRYST, 352, 2000, pp. 863
A new principle of information storage based on a realization of the revers
ible transition <<selective reflection-absorbance>> in photochromic liquid
crystalline (LC) copolymers was suggested. For this purpose a new family of
triple copolymers were synthesized by copolymerization of acrylic monomers
, containing nematogenic (phenylbenzoate), chiral (cholesterol), and photoc
hromic (spiropyran) fragments. Phase behaviour and optical properties of co
polymers were studied. Isomerization of spiropyran groups and formation of
merocyanine form under UV-irradiation (337 nm) of the polymer films was obs
erved. It should be noted that the maximum of the absorbance of polymer fil
ms coincides with maximum of selective light reflection. As a result the di
sappearance of the selective light reflection in the irradiated regions of
the films occurs. Scheme of the optical data recording and reading of infor
mation recorded on planarly oriented films of such copolymers was proposed.