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系統識別號 U0026-3006202014380900
論文名稱(中文) 可調式膽固醇液晶高分子膜結構色
論文名稱(英文) Structural Colors Based on Tunable Cholesteric Liquid Crystal Polymers
校院名稱 成功大學
系所名稱(中) 化學工程學系
系所名稱(英) Department of Chemical Engineering
學年度 108
學期 2
出版年 109
研究生(中文) 陳正捷
研究生(英文) Cheng-Chieh Chen
學號 N36071251
學位類別 碩士
語文別 英文
論文頁數 75頁
口試委員 指導教授-劉瑞祥
口試委員-吳文中
口試委員-吳逸謨
口試委員-陳澄河
口試委員-劉俊彥
中文關鍵字 結構色  膽固醇液晶  布拉格反射  光子晶體  結構色色料 
英文關鍵字 Structural colors  Cholesteric liquid crystals  Bragg’s reflection  Photonic crystals  Structural colorants 
學科別分類
中文摘要 與傳統色素的原理不同,結構色由於其高熱、光穩定性,及高解析度…等優點,成為現今最有前景的色素來源。膽固醇液晶是一種一維的光子晶體並且存在著特殊的布拉格反射,經由配向處理及適當的配方調整,可表現出結構色。本實驗由向列型液晶(RM257)、手性分子(CB15)、雙官能基單體(BAHB)以及光起始劑(Irgacure-184)所混合成的膽固醇液晶作為結構色的原料。
由紫外光-可見光光譜儀可確認出,我們所製備的膽固醇液晶布拉格反射出特定波長的光。此外,調整膽固醇液晶混合物所含的手性物質含量,可以使膽固醇液晶混合物反射出不同波段的光。藉由光罩選擇性聚合膽固醇混合物,我們製備出不同圖形且具結構色的高分子膜。
為了發展此結構色作為色料使用,我們將膽固醇液晶膜做成微小片狀碎片。考慮到解析度對於色料應用的重要性,膽固醇顆粒必須為奈米尺度。然而光的散射與繞射現象會使結構色消失。為了使布拉格反射現象發生,奈米顆粒的形狀要為片狀。我們將製備出的膽固醇片狀碎片與黏著劑混合而固定,來證實將膽固醇液晶膜作為色料應用的可能性。由實驗結果可看出不同顏色的圖案成功被製備出。理論上,奈米尺度的膽固醇碎片可以由飛秒雷射技術來製備。而我們的實驗結果指出結構色色料可由微小膽固醇片狀碎片來製備出。
英文摘要 Different from traditional absorption-based pigments, structural colors with the advantage of high stability of heat and light are the most promising sources of colorants now. Cholesteric liquid crystals, a kind of one-dimensional photonics exhibiting Bragg reflection, show structural colors with aligned processing and appropriate recipe of the components. To fabricate structural colors, cholesteric liquid crystals (CLCs) were used as the key materials including the mixtures of nematic LC (RM257), chiral dopant (CB15), bifunctional monomer, 4,4’-bis((6-acryloyloxy) hexyloxy) biphenyl (BHAB), and photoinitiator (Irgacure-184).
Bragg reflection of selective light wavelength of the fabricated CLC films were confirmed by UV-vis spectrometry. In addition, the reflection band wavelength of the CLC mixtures was tuned by adding different amount of chiral dopant. Various structural colored patterns were fabricated via the predesigned CLC mixtures through a pre-fabricated masks with UV irradiation.
To develop structural colorants, the synthesized CLC films were cut into small slices. Considering the resolution of printing image, fabrication of CLC nanoparticles is necessary. However, in the case of ground particles, light scattering and diffraction of nanoparticles results in opaque appearance and the disappearance of structural colors. To show Bragg reflection, slice construction is also necessary. To evidence the possibility of using the synthesized CLC films as colorants, the prepared CLC slices were fixed by polymer binders.
After printing of the prepared CLC paste, various colored patterns were observed. Theoretically, preparation of nano-sized CLC slices via laser technique is possible. The results suggest that the nano-sized CLC slices are available for the design of structure colorants.
論文目次 Contents
中文摘要..................................I
Abstract ................................. III
Contents..................................VI
List of Schemes ..............................IX
List of Tables ............................... X
List of Figures ..............................XI
1. Introduction ............................... 1
1-1 Preface……………………………………………………………….. 1
1-2 Research Motivation ........................... 2
2. Literature Review............................ 4
2-1 Introduction of Liquid crystals ..................... 4
2-2 Thermotropic Liquid Crystal ...................... 7
2-2-1 Nematic Liquid Crystal Phase ..................... 7
2-2-2 Smectic Liquid Crystal Phase.................... 8
2-2-3 Cholesteric Liquid Crystal Phase .................. 10
2-3 Characterization Methods of Liquid Crystals............. 13
2-3-1 POM Textures of Liquid Crystals [10] ................ 13
2-3-2 Liquid Crystal Phase Detected by DSC .............. 20
2-3-3 Liquid Crystal Phase Detected by XRD [14] ............ 21
2-4 Lyotropic Liquid Crystals ....................... 22
2-5 Anisotropic Properties of Liquid Crystals[15] ........... 23
2-5-1 Birefeingence of Liquid Crystals[16] ................ 24
2-5-2 Dielectric Properties of Liquid Crystals .............. 25
2-6 Introduction of Structural Colors.................... 27
2-6-1 Structural Colors Based on Photonic Crystals in Nature ...... 27
2-6-1-1 One-Dimensional (1D) Photonic Nanostructures in Nature .... 28
2-6-1-2 Two-Dimensional (2D) Photonic Nanostructures in Nature.... 28
2-6-1-3 Three-Dimensional (3D) Photonic Nanostructures in Nature ... 28
2-6-1-4 Tunable Structural Colors in Nature ................ 29
2-6-2 Structural Colors Based on Cholesteric Liquid Crystals....... 29
2-6-2-1 Cholesteric Liquid Crystal Inks ................. 31
2-6-2-2 Cholesteric Liquid Crystal Polymer Polymers .......... 31
2-7 Introduction of Femtosecond Laser .................. 32
3. Experimental Section .......................... 34
3-1 Materials ............................... 34
3-2 Instrument ............................... 35
3-3 Experimental Part ........................... 36
3-3-1 Synthesis of Bifunctional Monomer [37]............... 36
3-3-2 Fabrication of Liquid Crystal Cells ................. 37
3-3-3 Fabrication of Patterned Optical Object .............. 41
3-3-4 Fabrication of Cholesteric Liquid Crystal Particles ........ 41
4. Results and Discussion ........................ 43
4-1 Characterization of BAHB ....................... 43
4-1-1 Structure Identification of BAHB ................. 43
4-1-2 Thermal Properties of BAHB .................... 45
4-1-3 Optical Properties of BAHB.................... 47
4-2 Characterization of CLC Film .................... 48
4-2-1 Polymerization of CLC Mixtures .................. 48
4-2-2 Thermal Characterization of CLC Films ............... 50
4-2-3 Optical Characterization of CLC Films............... 52
4-2-4 Colorful Patterns Fabricated by Photomasks ............ 56
4-3 Cholesteric Liquid Crystalline Colorants ............... 58
4-3-1 CLC Particles by Suspension Polymerization........... 58
4-3-2 CLC Film Ground Particles..................... 62
4-3-3 Structural Colorants Based on Film Slices.............. 65
5. Conclusions .............................. 70
References ................................ 71
List of Schemes
Scheme 3-1 Synthetic route of bifunctional monomer BAHB....... 36
Scheme 3-2 Chemical structures of nematic liquid crystal monomer (RM257),
chiral dopant (CB15) and photo initiator (Irg-184) ........ 38
Scheme 3-3 Chemical structures of suspending agent (PVA) and thermal
initiator (AIBN) .......................... 42
List of Tables
Table 3-1 Components of CLC mixtures. (mg).............. 38
Table 4-1 Physical properties of nematic liquid crystal HSG22200-000. 55
List of Figures
Figure 1-1 Various colors of films were produced by quenching CLC films at
various temperature. ............................ 3
Figure 2-1 Phase transition of the matter and its molecular arrangement. [3]. 6
Figure 2-2 Various types of liquid crystalline molecules........... 6
Figure 2-3 Schematic representation of the molecular arrangement of nematic
liquid crystal phase. ............................. 8
Figure 2-4 (a) smectic A phase, (b) smectic C phase. ............ 9
Figure 2-5 The helical structure of the cholesteric liquid crystal phase and the
characteristic of circular dichorism of cholesteric liquid crystals [7]. ... 11
Figure 2-6 Schematic representation of three types of cholesteric liquid
crystals under polarized optical microscope. ................ 12
Figure 2-7 Schlieren texture of a nematic phase under planar anchoring
conditions, at low magnification [10]. ................... 14
Figure 2-8 Nematic thread-like texture [10]. .................. 14
Figure 2-9 The marble texture is probably the most commonly obtained
texture of nematic liquid crystals [10]. .................... 15
Figure 2-10 Typical fan-shaped textures of a SmA phase. The director
basically lies in the plane of the substrate and the smectic layers are
acrossed the fans [10]............................. 16
Figure 2-11 Transition from a nematic schlieren texture (right) to a SmC
schlieren texture (left) [10]. ......................... 17
Figure 2-12 A sample shows the broken fan-shaped texture of SmC on
cooling [10]. ................................. 17
Figure 2-13 Oily streaks texture of a cholesteric sample under planar
anchoring conditions [12]. ......................... 18
Figure 2-14 Schematic illustration of the cholesteric director configuration in
the fingerprint textures observed for homeotropic boundary conditions [10].
....................................... 19
Figure 2-15 Sample with a diverging cholesteric pitch under homeotropic
anchoring conditions, exhibiting so-called cholesteric fingers[10]. ..... 20
Figure 2-16 Schematic illustration of Bragg’s Law [14]............ 21
Figure 2-17 Schematic of 2D X-ray diffraction of dfferent types of liquid
crystal phases: (a) isotopic, (b) nematic, (c) smectic A, and (d) smectic C
[14]..................................... 22
Figure 2-18 Anisotropic properties of nematic liquid crystals....... 24
Figure 2-19 Schematic illustration of the birefringence of (a) positive uniaxial
LCs and (b) negative uniaxial liquid crystals[17]. .............. 25
Figure 2-20 The molecular alignments of liquid crystals with (a) positive . 26
Figure 2-21 Typical photonic nanostructures in natural creatures [20].(A)-(G)
exhibit inspiring examples of structural colors in nature. ......... 29
Figure 2-22 Sketch of cholesteric structure, showing the dependence of
molecular orientation on position [27]. ................... 30
Figure 2-23 Schematic of lower heat effect in femtosecond laser [36]. ... 33
Figure 2-24 Schematic of nano-slices made by femtosecond laser. .... 33
XIII
Figure 3-1 Schematic illustration of the preparation of aligned glass substrate.
....................................... 40
Figure 3-2 Schematic illustration of the preparation of CLC films ..... 40
Figure 4-1 The FT-IR spectrum of bifunctional monomer BAHB. ..... 44
Figure 4-2 The 1H-NMR spectrum of intermediate BHB. ......... 44
Figure 4-3 1H-NMR spectrum of bifunctional monomer BAHB. ..... 45
Figure 4-4 TGA thermogram of BAHB. .................. 46
Figure 4-5 DSC thermogram of BAHB with heating/cooling rate of 1oC/min.
....................................... 46
Figure 4-6 DSC thermogram of BAHB with heating/cooling rate of 1oC/min.
....................................... 47
Figure 4-7 FTIR spectra of (a) P, (b) B and (c) C samples before and after
polymerization............................... 49
Figure 4-8 TGA thermograms of (a) P, (b) B and (c) C CLC sample films. 51
Figure 4-9 POM textures of CLC films and appearing color of (a) P, (b) B and
(c) C. .................................... 52
Figure 4-10 Real images of (a) purple, (b) blue and (c) cyan CLC films.. 54
Figure 4-11 Reflection spectra of CLC films prepared with LC cells (a)
without and (b) with alignment layers. ................... 54
Figure 4-12 Reflection spectrum of the synthesized sample R showing
orange-red color............................... 56
Figure 4-13 Fabrication of a colorful pattern through a mask. ........ 57
Figure 4-14 Various colorful patters fabricated via photomasks. ...... 57
XIV
Figure 4-15 The SEM image of the synthesized spherical particles.... 59
Figure 4-16 The POM image of the synthesized CLC particles. ....... 59
Figure 4-17 The Schematic illustration of molecular interactions occurred at
interface of LC droplets........................... 60
Figure 4-18 The radial conformation and corresponding POM image of 5CB
droplets [44]. ................................ 60
Figure 4-19 The reflection spectrum of the synthesized CLC particles. ... 61
Figure 4-20 Real images of the original blue film and the milky white
appearance of the ground particles.................... 63
Figure 4-21 The POM image of the ground CLC particles ......... 63
Figure 4-22 The reflection spectrum of the ground particles......... 64
Figure 4-23 The SEM image of ground particles............... 64
Figure 4-24 Appearance of the prepared CLC slices showing various colors.
....................................... 66
Figure 4-25 NCKU pattern fabricated by the developed different color CLC
slices fixed by a transparent binder. .................... 67
Figure 4-26 Reflection spectra of binder fixed P and C sample slices showing
purple and cyan, respectively. ....................... 67
Figure 4-27 A hummingbird gradient pattern was fabricated by the
synthesized CLC slices.......................... 68
Figure 4-28 The schematic reflection of slices free from light scattering . 68
Figure 4-29 The preparation of CLC films with various thickness. .... 69
Figure 4-30 Reflection spectra of CLC films with different film thickness.69
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