Photooptical behavior of hydrogen-bonded polymer blends with low-molecular-mass chiral dopants: New materials with a photocontrolled pitch of a cholesteric helix

The phase behavior and optical and photooptical properties of hydrogen-bond ed blends of photosensitive chiral dopants with carboxyl-containing nematog enic comb-shaped acrylic copolymer were studied. Chiral dopants contain a p yridinine fragment capable of forming hydrogen bonds with acidic groups, a C=C double bond relatively which the occurrence of E-Z photoisomerization i s possible, and optically active groups based on menthone and menthol. The resulting blends form a chiral nematic phase within a wide temperature inte rval, their films with planar orientation exhibit a selective light reflect ion in the visible and IR spectral ranges, and the maximum selective reflec tion wavelength depends on the temperature and duration of UV irradiation o f the films. It was shown that a shift in the selective light reflection pe ak to the long-wave region of the spectrum under the action of UV radiation is related to a reduction in the twisting power of chiral photochromic dop ants resulting from their E-Z photoisomerization. The obtained blends may b e used as media for the optical data recording and storage.