Mesomorphic and structural properties of liquid crystalline side-chain polymethacrylates: from smectic C* to columnar phases
Sergey N. Sulyanov
Pavel V. Dorovatovskii
Alexey Yu. Bobrovsky
Valery P. Shibaev
Martin Cigl
Vĕra Hamplová
Alexej Bubnov
Boris I. Ostrovskii
10.6084/m9.figshare.7212212.v1
https://tandf.figshare.com/articles/journal_contribution/Mesomorphic_and_structural_properties_of_liquid_crystalline_side-chain_polymethacrylates_from_smectic_C_to_columnar_phases/7212212
<p>The chiral methacrylate monomers with photosensitive azobenzene group possessing the orthogonal smectic A* and tilted smectic C* (Sm-C*) phases have been synthesised and characterised. The monomers have been used as functional side chains for the design of corresponding polymethacrylates. X-ray diffraction has been applied to elucidate the structure and phase behaviour of liquid-crystalline side-chain polymethacrylates with azobenzene-containing central core, chiral fragments and aliphatic spacers and tails of different length. X-ray patterns of polymethacrylates oriented fibres impose the tilted Sm-C* order as a basic structure of these materials. This is complemented by a regular pattern of small-angle diffuse spots, which implies complex positional order on the local scale and serves as a precursor for the formation of a columnar phase. The increase of the total length of the aliphatic tail and spacer of the side-chain fragments leads to formation of the tilted columnar phase (Col<sub>tilt</sub>*) with two-dimensional monoclinic lattice. For the polymer containing 10 methylene units in both, spacer and aliphatic tail, the Col<sub>tilt</sub>* precedes the formation of the Sm-C* phase. The observed structural changes are explained as due to coupling between the smectic ordering of the mesogenic side groups and the polymer backbone conformation.</p>
2018-10-16 11:35:57
Liquid crystals
methacrylate monomers
side-chain polymers
smectic and columnar phases
X-ray diffraction
small-angle diffuse scattering