Mesomorphic and structural properties of liquid crystalline side-chain polymethacrylates: from smectic C* to columnar phases. Issue 6 (3rd May 2019)

• Record Type: Journal Article
• Authors: Sulyanov, Sergey N.; Dorovatovskii, Pavel V.; Bobrovsky, Alexey Yu.; Shibaev, Valery P.; Cigl, Martin; Hamplová, Vĕra; Bubnov, Alexej; Ostrovskii, Boris I.
• Is Part Of: Liquid crystals. Volume 46:Issue 6(2019)
• Page Start: 825
• Page End: 834
• Publication Date: 2019-05-03
• Subjects: Liquid crystals -- methacrylate monomers -- side-chain polymers -- smectic and columnar phases -- X-ray diffraction -- small-angle diffuse scattering; Liquid crystals -- Periodicals; 548.905
• DOI: 10.1080/02678292.2018.1530386
• Languages: English
• ISSNs: 0267-8292

Abstract

ABSTRACT: 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 (Coltilt *) with two-dimensional monoclinic lattice. For the polymer containing 10 methylene units in both, spacer and aliphatic tail, the Coltilt * 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. Graphical Abstract: