臺灣博碩士論文加值系統

本篇論文主要研究三個主題，第一個是研究鐵電液晶摻雜膽固醇液晶平板樣品之反射顏色於整個白光區域做溫度調控。第二個是利用ITO膜本身可電致發熱特性，使鐵電液晶摻雜膽固醇液晶平板樣品之反射顏色於整個白光區域做低直流電壓調控。第三個乃透過可撓式石墨烯電致發熱薄膜與液晶同軸電紡絲結合，在施加低直流電壓下，使鐵電液晶摻雜膽固醇液晶微米纖維絲之反射顏色可電控涵蓋整個白光區域。 實驗結果發現，鐵電液晶摻雜入膽固醇液晶時，可提高其層列相與膽固醇相之相變溫度至室溫附近，當溫度接近此相變點時螺旋結構會大量解旋使反射波長大幅紅移但波帶結構仍維持完整。若進一步藉由簡單地施加低直流電壓於樣品ITO基板上，便可達到低電壓調控樣品反射波段於全白光區做寬頻域之反射波帶或顏色調控 (〈 5 V)。另外，利用同軸電紡絲技術將鐵電液晶摻雜膽固醇液晶微米纖維絲噴塗於可撓式石墨烯電致發熱片，經過施加中等大小的直流電壓範圍(〈 24 V)於石墨烯電致發熱片上，其反射顏色亦可於整個白光區做廣頻域之電調控。對於無論平板樣品或纖維樣品，其溫控或電控反射顏色特性皆具有可逆性與可重複性。由上述結果可知，可低直流電壓調控膽固醇液晶平板或微纖維樣品分別在智能顯示與雷射以及智能感測元件及可穿戴式智能布料上之應用有相當之應用潛力。

This thesis mainly focused on three topics. The first is the investigation for the temperature-tuning of the reflective color of the ferroelectric liquid crystal doped cholesteric liquid crystal (FLC-CLC) across the entire visible region. The second topic is the study for electrical tuning of the reflective color of the FLC-CLC across the entire visible region in a low DC voltage range by using the high electrothermal feature of the ITO film. The third one is the investigation for electrical tuning of the reflective color of the FLC-CLC across the entire visible region by merging a flexible graphene electrothermal heater with the coaxial electrospinng technique.
Experimental results show that the smectic-cholesteric phase transition temperature can be increased to near the room temperature such that the helix untwists significantly at near the transition temperature and thus the reflection band significantly red-shifts with a complete band structure. The reflection band or color of the FLC-CLC sample can be tuned across the wide band of the entire visible region when the ITO substrate of the sample is simply applied at a low DC voltage regime (〈 5 V). In addition, the FLC-CLC microfibers are electrospun and sprayed on the flexible graphene electrothermal heater film. The reflection band or color of the microfibers can also be tuned electrically across the wide band of the entire visible region at a moderate DC voltage regime (〈 24 V) on the graphene film. The planar or microfibers sample both possess a high reversibility and repeatability for the above-mentioned thermal and electrical tunabilities of the reflective band or color. Based on the above-mentioned experimental results, the electrically tunable FLC-CLC planar sample with ITO substrates and microfibers sample are highly potential for the applications of smart displays and lasers and smart sensors and textiles, respectively.

摘要 I
Abstract II
致謝 IV
目錄 V
圖目錄 VIII
表目錄 XV
第一章 緒論 1
第二章 液晶介紹 3
2.1 何謂液晶 3
2.2 液晶分類 4
2.2.1 溶致型液晶 4
2.2.2 熱致型液晶 4
2.3 液晶物理特性 9
2.3.1光學異向性與雙折射性 9
2.3.2 介電異向性 12
2.3.3 連續彈性體理論 13
2.3.4 溫度對液晶折射率之影響 14
第三章 膽固醇液晶與鐵電型液晶 16
3.1 膽固醇液晶之光學特性 16
3.2 外在因素對膽固醇液晶螺距的影響 17
3.2.1 溫度 17
3.2.2 磁場 18
3.2.3 電場 19
3.3 鐵電型液晶基本性質 20
3.4 表面穩定鐵電型液晶 21
第四章 電紡絲技術與電致發熱片 23
4.1 電紡絲背景 23
4.2 電紡絲紡織過程 23
4.2.1 電紡絲與電噴霧 24
4.2.2 電紡絲針頭泰勒錐形成 24
4.2.3電紡絲拉伸的不穩定性 26
4.2.4電紡絲之收集 26
4.2.5 電紡絲的形態 27
4.3 同軸電紡絲技術 27
4.4石墨烯電致發熱片原理 28
第五章 樣品製備與實驗架設 32
5.1 實驗材料 32
5.2製作液晶平板樣品 34
5.2.1 玻璃的清潔 34
5.2.2製備空樣品 35
5.2.3液晶混合物之樣品 35
5.3電紡絲與電噴霧之製備 36
5.4液晶同軸電紡絲實驗架設 36
5.5利用電噴霧製作可撓式電致發熱片之實驗架設 37
5.6實驗觀察與量測系統裝置 38
5.6.1偏光顯微鏡觀察液晶樣品與同軸電紡絲 38
5.6.2反射頻譜量測架設 39
第六章 結果與討論 42
6.1溫控與利用ITO電致發熱膜電控FLC-CLC平板樣品 42
6.1.1不同FLC種類及濃度摻雜CLC平板樣品於溫控下之反射特性 42
6.1.2 FLC-CLC平板樣品升降溫之可逆性與反應速率 56
6.1.3利用ITO電致發熱膜電控FLC-CLC平板樣品之反射特性 64
6.2利用石墨烯電致發熱膜電控FLC-CLC樣品 68
6.2.1石墨烯-玻璃電致發熱平板樣品測試 68
6.2.2石墨烯/PDMS可撓式電致發熱片性能測試 71
6.3電致發熱片結合液晶同軸電紡絲之電致變色應用 73
6.3.1液晶同軸電紡絲在偏光顯微鏡下的觀察 73
6.3.2液晶同軸電紡絲噴塗於電致發熱片上之電致變色應用 77
第七章 結論與未來展望 80
7.1 結論 80
7.2 未來展望 80
參考文獻 82

1.J. T. McCann, D. Li, and Y. Xia, “Electrospinning of nanofibers with core-sheath, hollow, or porous structures, J. Mater. Chem. 15, 735–738 (2005).
2.S. Wen, R. Zhang, S. Hu, L. Zhang, and L. Liu, “Improved fluorescence properties of core–sheath electrospun nanofibers sensitized by silver nanoparticles, Opt. Mater. 47, 263–269 (2015).
3.D. H. Reneker, A. L. Yarin, H. Fong, and S. Koombhongse, “Bending instability of electrically charged liquid jets of polymer solutions in electrospinning, J. Appl. Phys. 87, 45314547 (2000).
4.H. Fong and D. H. Reneker, Structure Formation in Polymeric Fibers, Eds: D. R. Salem, M. V. Sussman, (Carl Hanser, Munchen, 2001).
5.A. L. Yarin, S. Koombhongse, and D. H. Reneker, “Bending instability in electrospinning of nanofibers, J. Appl. Phys. 89, 30183026 (2001).
6.Y. Wu, Q. An, J. Yin, T. Hua, H. Xie, G. Li, and H. Tang, “Liquid crystal fibers produced by using electrospinning technique, Colloid Polym. Sci. 286, 897–905 (2008).
7.A. Greiner and J. H. Wendorff, “Electrospinning: a fascinating method for the preparation of ultrathin fibers, Angew. Chem. 46, 5670–5703 (2007).
8.X. Lu, C. Wang, and Y. Wei, “One-dimensional composite nanomaterials: synthesis by electrospinning and their applications, Small 5, 2349–2370 (2009).
9.Z.G. Zheng, Y. Li, H.K. Bisoyi, L. Wang, T.J. Bunning, and Q. Li, “Three-dimensional control of the helical axis of a chiral nematic liquid crystal by light, Nature. 531, 352–357 (2016).
10.A. C. Arsenault, D. P. Puzzo, I. Manners, and G. A. Ozin, “Photonic-crystal full-colour displays, Nat. Photonics 1, 468–472 (2007).
11.A. Ogiwara and H. Kakiuchida, “Thermally turnable light filter composed of cholesteric liquid crystals with different temperature dependence, Sol. Energy Mater. Sol. Cells 157, 250258 (2016).
12.J. P. Lagerwall, J. T. McCann, E.Formo, G. Scalia, and Y. Xia, “Coaxial electrospinning of microfibres with liquid crystal in the core, Chem. Commun. 42, 5420–5422 (2008).
13.E. Enz, U. Baumeister, and J. Lagerwall, “Coaxial electrospinning of liquid crystal-containing poly(vinylpyrrolidone) microfibres, J. Org. Chem. 5, 18 (2009).
14.J. D. Lin, C. P. Chen, L. J. Chen, Y. C. Chuang, S. Y. Huang, and C. R. Lee, “Morphological appearances and photo-controllable coloration of dye-doped cholesteric liquid crystal/polymer coaxial microfibers fabricated by coaxial electrospinning technique, Opt. Express 3, 3112–3126 (2016).
15.S. Chandrasekhar, Liquid Crystal (Cambridge University Press, New York, 1992).
16.I. C. Khoo, Liquid Crystals: Physical Properties and Nonlinear Optical Phenomena (John Wiley ＆ Sons, New York, 1995).
17.Eds. H. –S. Kitzerow and Ch. Bahr, Chirality in Liquid Crystals (Springer, New York, 2001).
18.P. G. d. Gennes, “Calcul de la distorsion d'une structure cholesterique par un champ magnetique, Solid State Commun. 6, 163165 (1968).
19.W. R. Chen and J. C. Hwang, “The phase behaviour and optical properties of a nematic/chiral dopant liquid crystalline mixture system, Liq. Cryst. 31, 15391546 (2004).
20.R. B. Meyer, “Effects of electric and magnetic fields on the structure of cholesteric liquid crystals, Appl. Phys. Lett. 12, 281–282 (1968).
21.F. Castles, S. C. Green, D. J. Gardiner, S. M. Morris, and H. J. Coles, “Flexoelectric coefficient measurements in the nematic liquid crystal phase of 5CB, AIP Adv. 2, 022137 (2012)
22.N. A. Clark and S. T. Lagerwall, “Submicrosecond bistable electro-optic switching in liquid-crystals. Appl. Phys. Lett. 36, 899–901 (1980)
23.Z. C. Sun, E. Zussman, A. L. Yarin, J. H. Wendorff, and A. Greiner, “Compound core-shell polymer nanofibers by co-electrospinning, Adv. Mater. 15, 1929–1932 (2003).
24.Q. Li, Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications (Wiley, New Jersey, 2012).
25.D. H. Reneker and A. L. Yarin, “Electrospinning jets and polymer nanofibers, Polymer 49, 2387–2425 (2008).
26.P. Katta, M. Alessandro, R. D. Ramsier, and G. G. Chase, “Continuous electrospinning of aligned polymer nanofibers onto a wire drum collector, Nano Lett. 4, 2215–2218 (2004).
27.L. S. Carnell, E. J. Siochi, N. M. Holloway, R. M. Stephens, C. Rhim, L. E. Niklason, and R. L. Clark, “Aligned mats from electrospun single fibers, Macromol. 41, 5345–5349 (2008).
28.D. Li and Y. Xia, “Direct fabrication of composite and ceramic hollow nanofibers by electrospinning, Nano Lett. 4, 933–938 (2004).
29.J. He, Y. Chen, W. Lv, K. Wen, P. Li, F. Qi, Z. Wang, W. Zhang, Y. Li, W. Qin, and W. He, “Highly-flexible 3D Li2S/grapheme cathode for high-performance lithium sulfur batteries, J. Power Sources 327, 474–480 (2016).
30.D. Jung, M. Han, and G. S. Lee,xeater Using Multiwalled Carbon Nanotube Sheet, J. Vac. Sci. Technol., B: Microelectron. Nanometer Struct.-Process., Meas., Phenom. 32, 04E105 (2014).
31.R. Gupta, K. D. M. Rao, S. Kiruthika, and G. U. Kulkarni, “Visibly Transparent Heaters, ACS Appl. Mater. Interfaces 8, 12559–12575 (2016).
32.J. J. Bae, S. C. Lim, G. H. Han, Y. W. Jo, D. L. Doung, E. S. Kim, S. J. Chae, T. Q. Huy, N. Van Luan, and Y. H. Lee, “Heat Dissipation of Transparent Graphene Defoggers, Adv. Funct. Mater. 22, 48194826 (2012).
33.田民波 著，林怡欣 校定，TFT液晶顯示原理與技術 (五南圖書出版公司，台灣，2008).
34.H. Y. Liu, C. T. Wang, C. Y. Hsu, and T. H. Lin, “Pinning effect on the photonic bandgaps of blue-phase liquid crystal, Appl. Opt. 50, 16061609 (2011).
35.C. Bahr, Chirality in Liquid Crystals, ed. H.-S. Kitzerow and C. Bahr, (Springer-Verlag, New York, 2001), Ch. 8.
36.L. M. Blinov and V. G. Chigrinov, Electrooptic Effects in Liquid Crystal Materials, (Springer, New York 1994), Ch. 6.
37.T. H. Lin and H. C. Jau, “Electrically controllable laser based on cholesteric liquid crystal with negative dielectric anisotropy, Appl. Phys. Lett. 88, 061122 (2006).
38.L. D. Sio, G. Palermo, V. Caligiuri, and C. Umeton, “Electro and pressure tunable cholesteric liquid crystal devices based on ion-implanted flexible substrates, J. Mater. Chem. C 1, 77987802 (2013).
39.S. S. Choi and H. J. Coles, “Electrically tuneable liquid crystal photonic bandgaps, Adv. Mater. 21, 39153918 (2009).
40.E. Enz and J. Lagerwall, “Electrospun microfibres with temperature sensitive iridescence from encapsulated cholesteric liquid crystal, J. Mater. Chem. 20, 6866–6872 (2010).
41.J. P. Lagerwall, J. T. McCann, E.Formo, G. Scalia, and Y. Xia, “Coaxial electrospinning of microfibres with liquid crystal in the core, Chem. Commun. 42, 5420–5422 (2008).