PHOTOINDUCED 3D ORIENTATIONAL ORDER IN LIQUID CRYSTALLINE AZOPOLYMERS STUDIED BY THE METHOD OF ATTENUATED TOTAL REFLECTION

The attenuated total reflection (ATR) technique is applied to study 3D ordering in the films of liquid crystalline (LC) polymers. We used a series of LC side-chain polyesters differing by the tail substitutes (NO2, OCH3 and OC4H9) in azochromophore. The 3D order is studied in non-irradiated films as well as in the films irradiated by polarized light with λex1 = 365 nm or/and with λex2 = 457 nm strictly distinguished by absorption efficiency of azochromophores. The orientation under irradiation is compared to that after irradiation. Biaxial, uniaxial as well as isotropic 3D ordering of azochromophores is realized. The observed uniaxial spatial structures can be classified by analogy with crystal optics; 1) positive C films with preferential out-of-plane orientation of azochromophores; 2) negative C films with in-plane random orientation of azochromophores having symmetry axis in the film normal direction; 3) positive A films with in-plane uniaxial orientation, and 4) negative A films characterized by oblat...