Solvent isotopic effect on the phase transition of lyotropic chromonic liquid crystals: Heavy water makes mesogens less charged
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arXiv
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| Natura: | Preprint |
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2024
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| _version_ | 1866917771423514624 |
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| author | Cheon, Jiyong Jeong, Joonwoo |
| author_facet | Cheon, Jiyong Jeong, Joonwoo |
| contents | The interplay among solute and solvent molecules in lyotropic mesophases governs their physicochemical properties, such as phase behaviors and viscoelasticity. In our model system, a lyotropic chromonic liquid crystal (LCLC) made by disodium cromoglycate (DSCG), charged plank-like molecules self-assemble to form elongated aggregates via non-covalent attractions in water (H$_{2}$O). The aggregates align to exhibit liquid crystalline phases: nematic and columnar phases. Here, we report the isotopic effect on the phase behavior of the LCLC when D$_2$O is substituted for H$_2$O. D$_2$O-DSCG exhibits higher nematic-to-isotropic phase transition temperatures than H$_2$O-DSCG. X-ray scattering reveals considerably longer inter-aggregate correlation lengths in D$_2$O-LCLCs. In contrast, the other microstructural properties, such as inter-aggregate distances and intra-aggregate correlation lengths, remain almost the same. Our $^{23}$Na FT-NMR measurement reveals that D$_2$O-DSCG aggregates are less charged with more counter-ions, Na$^+$, bound to them than H$_2$O-DSCG aggregates. Weaker electrostatic repulsion between aggregates may stabilize the nematic phase, and this solvent isotopic effect may generally apply to diverse aqueous lyotropic mesophases with electrostatic interactions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_05097 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Solvent isotopic effect on the phase transition of lyotropic chromonic liquid crystals: Heavy water makes mesogens less charged Cheon, Jiyong Jeong, Joonwoo Soft Condensed Matter The interplay among solute and solvent molecules in lyotropic mesophases governs their physicochemical properties, such as phase behaviors and viscoelasticity. In our model system, a lyotropic chromonic liquid crystal (LCLC) made by disodium cromoglycate (DSCG), charged plank-like molecules self-assemble to form elongated aggregates via non-covalent attractions in water (H$_{2}$O). The aggregates align to exhibit liquid crystalline phases: nematic and columnar phases. Here, we report the isotopic effect on the phase behavior of the LCLC when D$_2$O is substituted for H$_2$O. D$_2$O-DSCG exhibits higher nematic-to-isotropic phase transition temperatures than H$_2$O-DSCG. X-ray scattering reveals considerably longer inter-aggregate correlation lengths in D$_2$O-LCLCs. In contrast, the other microstructural properties, such as inter-aggregate distances and intra-aggregate correlation lengths, remain almost the same. Our $^{23}$Na FT-NMR measurement reveals that D$_2$O-DSCG aggregates are less charged with more counter-ions, Na$^+$, bound to them than H$_2$O-DSCG aggregates. Weaker electrostatic repulsion between aggregates may stabilize the nematic phase, and this solvent isotopic effect may generally apply to diverse aqueous lyotropic mesophases with electrostatic interactions. |
| title | Solvent isotopic effect on the phase transition of lyotropic chromonic liquid crystals: Heavy water makes mesogens less charged |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2409.05097 |