Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes
A small quantity of hexagonal boron nitride (<i>h</i>-BN) flakes is doped into a nematic liquid crystal (LC). The epitaxial interaction between the LC molecules and the <i>h</i>-BN flakes rising from the <i>π</i>−<i>π</i> el...
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| Format: | Article |
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MDPI AG
2020-02-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/10/2/123 |
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| author | Rajratan Basu Lukas J. Atwood George W. Sterling |
| author_facet | Rajratan Basu Lukas J. Atwood George W. Sterling |
| author_sort | Rajratan Basu |
| collection | DOAJ |
| description | A small quantity of hexagonal boron nitride (<i>h</i>-BN) flakes is doped into a nematic liquid crystal (LC). The epitaxial interaction between the LC molecules and the <i>h</i>-BN flakes rising from the <i>π</i>−<i>π</i> electron stacking between the LC’s benzene rings and the <i>h</i>-BN’s honeycomb structure stabilizes pseudo-nematic domains surrounding the <i>h</i>-BN flakes. Electric field-dependent dielectric studies reveal that the LC-jacketed <i>h</i>-BN flakes follow the nematic director reorientation upon increasing the applied electric field. These anisotropic pseudo-nematic domains exist in the isotropic phase of the LC+<i>h</i>-BN system as well, and interact with the external electric field, giving rise to a nonzero dielectric anisotropy in the isotropic phase. Further investigations reveal that the presence of the <i>h</i>-BN flakes at a low concentration in the nematic LC enhances the elastic constants, reduces the rotation viscosity, and lowers the pre-tilt angle of the LC. However, the Fréedericksz threshold voltage stays mostly unaffected in the presence of the <i>h</i>-BN flakes. Additional studies show that the presence of the <i>h</i>-BN flakes enhances the effective polar anchoring strength in the cell. The enhanced polar anchoring strength and the reduced rotational viscosity result in faster electro-optic switching in the <i>h</i>-BN-doped LC cell. |
| first_indexed | 2024-04-14T01:27:37Z |
| format | Article |
| id | doaj.art-cfdddb7533114eac8b1ad41d35f34f4e |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-04-14T01:27:37Z |
| publishDate | 2020-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-cfdddb7533114eac8b1ad41d35f34f4e2022-12-22T02:20:21ZengMDPI AGCrystals2073-43522020-02-0110212310.3390/cryst10020123cryst10020123Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN FlakesRajratan Basu0Lukas J. Atwood1George W. Sterling2Soft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, MD 21402, USASoft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, MD 21402, USASoft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, MD 21402, USAA small quantity of hexagonal boron nitride (<i>h</i>-BN) flakes is doped into a nematic liquid crystal (LC). The epitaxial interaction between the LC molecules and the <i>h</i>-BN flakes rising from the <i>π</i>−<i>π</i> electron stacking between the LC’s benzene rings and the <i>h</i>-BN’s honeycomb structure stabilizes pseudo-nematic domains surrounding the <i>h</i>-BN flakes. Electric field-dependent dielectric studies reveal that the LC-jacketed <i>h</i>-BN flakes follow the nematic director reorientation upon increasing the applied electric field. These anisotropic pseudo-nematic domains exist in the isotropic phase of the LC+<i>h</i>-BN system as well, and interact with the external electric field, giving rise to a nonzero dielectric anisotropy in the isotropic phase. Further investigations reveal that the presence of the <i>h</i>-BN flakes at a low concentration in the nematic LC enhances the elastic constants, reduces the rotation viscosity, and lowers the pre-tilt angle of the LC. However, the Fréedericksz threshold voltage stays mostly unaffected in the presence of the <i>h</i>-BN flakes. Additional studies show that the presence of the <i>h</i>-BN flakes enhances the effective polar anchoring strength in the cell. The enhanced polar anchoring strength and the reduced rotational viscosity result in faster electro-optic switching in the <i>h</i>-BN-doped LC cell.https://www.mdpi.com/2073-4352/10/2/123nematic liquid crystals<i>h</i>-bn flakesdielectric anisotropyrotational viscosityanchoring energyelectro-optic effect |
| spellingShingle | Rajratan Basu Lukas J. Atwood George W. Sterling Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes Crystals nematic liquid crystals <i>h</i>-bn flakes dielectric anisotropy rotational viscosity anchoring energy electro-optic effect |
| title | Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes |
| title_full | Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes |
| title_fullStr | Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes |
| title_full_unstemmed | Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes |
| title_short | Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with <i>h</i>-BN Flakes |
| title_sort | dielectric and electro optic effects in a nematic liquid crystal doped with i h i bn flakes |
| topic | nematic liquid crystals <i>h</i>-bn flakes dielectric anisotropy rotational viscosity anchoring energy electro-optic effect |
| url | https://www.mdpi.com/2073-4352/10/2/123 |
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