New Principle of Optical Data Recording Based on Reversible Transition “Selective Reflection—Absorbance” in Photochromic Cholesteric Copolymers

Abstract

A new principle of information storage based on a realization of the reversible 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 photochromic (spiropyran) fragments. Phase behaviour and optical properties of copolymers were studied. Isomerization of spiropyran groups and formation of merocyanine form under UV-irradiation (337 nm) of the polymer films was observed. It should be noted that the maximum of the absorbance of polymer films coincides with maximum of selective light reflection. As a result the disappearance of the selective light reflection in the irradiated regions of the films occurs. Scheme of the optical data recording and reading of information recorded on planarly oriented films of such copolymers was proposed.