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Photo‐Orientation Phenomena in Photochromic Liquid Crystalline Azobenzene‐Containing Polymethacrylates with Different Spacer Length
Author(s) -
Bobrovsky Alexey,
Shibaev Valery,
Piryazev Alexey,
Anokhin Denis V.,
Ivanov Dimitri A.,
Sinitsyna Olga,
Hamplova Vera,
Kaspar Miroslav,
Bubnov Alexej
Publication year - 2017
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201700127
Subject(s) - azobenzene , photochromism , photoisomerization , polymer , materials science , irradiation , differential scanning calorimetry , dichroism , polarization microscopy , polarized light microscopy , chromophore , optical microscope , liquid crystal , photochemistry , thermal stability , crystallography , microscopy , optics , chemistry , optoelectronics , scanning electron microscope , isomerization , nanotechnology , composite material , organic chemistry , thermodynamics , catalysis , physics , nuclear physics
Synthesis and investigation of the phase behavior and photo‐optical properties of two chiral liquid‐crystalline polymers with azobenzene‐containing side groups having different spacer lengths, 6 and 10 methylene groups ( PMAzo‐6 and PMAzo‐10 , respectively) are described. Formation of different smectic phases and high‐temperature cholesteric phase is studied by polarizing optical microscope, differential scanning calorimetry, and X‐ray investigations. It is shown that UV‐irradiation induces effective reversible E – Z photoisomerization in polymer solutions and films. Atomic force microscopy (AFM) study reveals substantial changes in the surface topography of the polymer PMAzo‐6 film after UV‐irradiation, whereas PMAzo‐10 surface remains the same. Irradiation by polarized light (457 nm) results in photo‐orientation process in polymer films consequential in significant alignment of the chromophores in direction perpendicular to the polarization plane of the incident light. A significant difference is found in thermal stability of the photoinduced alignment; an annealing of PMAzo‐10 irradiated samples results in a slight decrease of dichroism values (down to 0.57); whereas the dichroism increases up to very high values (0.91) for PMAzo‐6 .