Orodepo, G O and Bej, S and Gowd, E B and Ramakrishnan, S (2022) Main-chain side-chain combined liquid crystalline polymers bearing azobenzene and biphenyl-based mesogens–segregation of the mesogens within two distinct layers. In: Liquid Crystals .
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Two different mesogenic units, namely biphenyl and azobenzene, were installed centrally within the polymer backbone and pendant alkylene segments; the purpose was to examine if chain folding of the backbone occurs so as to segregate the azobenzene and biphenyl units in adjacent layers of a smectic-type ordering. Two sets of isomeric main-chain side-chain liquid crystalline polymers (MCSC-LCPs), namely SC-AzoCx-MC-BPCx and SC-BPCx-MC-AzoCx, (x=6 or 10) were synthesised; the former series has biphenyl in the backbone and azobenzene in the side-chain, while their locations are switched in the latter. Two different alkylene segments (Cx) were examined, namely C6 and C10, which represent the spacer segments within the backbone and in the side-chain; furthermore, the same alkyl length was also retained for the tail segment on the side-chain mesogenic unit to ensure its symmetric location. It was observed that all four polymers were semicrystalline at room temperature and exhibited a smectic mesophase upon melting. Both DSC and X-ray scattering studies revealed that the two isomeric polymers, wherein the locations of the azobenzene and biphenyls were switched, behaved almost identically; neither the phase transition temperatures nor smectic layer spacings were influenced by the location of the mesogens. A second series, namely SC-AzoCx-MC-BPCy and SC-BPCx-MC-AzoCy, where the length of alkylene spacers in the side-chain (Cx) and backbone (Cy) is different, was also studied; this was done to examine the influence of unequal alkylene segment lengths on the mesophase structure and interlayer spacing, and importantly, whether the zigzag folding-induced formation of a layered structure is retained, despite their unsymmetrical nature. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
| Item Type: | Journal Article |
|---|---|
| Publication: | Liquid Crystals |
| Publisher: | Taylor and Francis Ltd. |
| Additional Information: | The copyright for this article belongs to Taylor and Francis Ltd. |
| Department/Centre: | Division of Chemical Sciences > Inorganic & Physical Chemistry |
| Date Deposited: | 23 May 2022 06:00 |
| Last Modified: | 23 May 2022 06:00 |
| URI: | https://eprints.iisc.ac.in/id/eprint/71861 |
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