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A study on the optimized molecular structures for high dichroism and orientation in PVA-based polarizing films and guest-host coatable polarizers : PVA계 편광필름과 코팅형 게스트-호스트 편광자에서 고이색성과 고배향이 가능한 최적분자구조에 관한 연구

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dc.contributor.advisor김재필-
dc.contributor.author장재복-
dc.date.accessioned2017-07-13T05:44:33Z-
dc.date.available2017-07-13T05:44:33Z-
dc.date.issued2015-02-
dc.identifier.other000000025314-
dc.identifier.urihttps://hdl.handle.net/10371/117985-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2015. 2. 김재필.-
dc.description.abstract분자 구조가 편광효율에 미치는 영향을 고찰하고 고성능 편광자를 개발하기 위한 이론적 기반을 형성하기 위하여 이색성 염료의 광학적 비등방성과 배향거동에 관한 연구를 진행하였다. 이를 위해 20개의 신규염료를 합성하였고 PVA-염료 편광필름들과 코팅형 게스트-호스트 편광자들을 제작하였다. 각각의 결과들은 선형성, 전이쌍극자, 호스트물질과의 친화성을 중점으로 심도 있게 비교∙분석되었다.
선형성은 염료의 이색성과 배향거동에 동시에 영향을 미치는 인자이다. 염료의 선형성은 아조연결과 말단치환기의 위치변화에 의해 바뀌게 된다. 길고 선형적인 분자구조는 높은 전이쌍극자를 형성하는데 유리하고 기하학적으로 높은 정렬도를 가능케 하였다. 선형성은 PVA계 편광필름과 코팅형 게스트-호스트 편광자 모두에서 중요한 인자로 작용하였다.
전이쌍극자는 특정파장의 빛을 선택적으로 흡수하고 편광화시키는데 본질적인 요소로 작용한다. 비등방적인 전이쌍극자는 공액 이중결합 시스템 내에서 전하이동의 방향에 의해 결정되며 전자 공여성기 및 구인성기의 유도효과에 따라 달라지는 전하분포에 영향을 받는다. 고이색성비는 전기적 방해물이 없는 원활한 전자흐름과 장축 방향에서 틀어짐이 없는 전하분포, 그리고 전이가능한 π전자들이 풍부한 분자구조에서 달성되었다.
호스트물질과의 친화성은 분자들의 정렬과 배향을 좌우하는 중요한 요소로 염료분자구조에 따른 다양한 분자간상호작용에 의해 영향을 받는다. 반데르발스힘, 수소결합, π-π 상호작용, 정전기적 효과, 친수성/소수성 비, 극성, 입체장애들이 분자간 상호작용의 요소로 분석되었다. 일반적으로 반데르발스힘과 입체장애가 PVA계 편광필름과 코팅형 편광자 모두에서 친화성과 배향에 중대한 영향을 미치는 요인으로 작용하였다. PVA계 편광필름에서는 수소결합이 큰 영향력을 보인 반면 코팅형 편광필름에서는 극성이 이색성비를 결정하는데 중요한 역할을 하였다.
호스트물질에서의 염료 농도 역시 이색성비를 결정하는 중요한 요소로 작용하였다. 높은 이색성비를 달성하기 위해서 PVA계 편광필름에서는 최적 농도를 맞추는 것이 중요하였으며 코팅형 편광자에서는 허용농도를 넘지 않는 것이 중요하였다.		-
dc.description.abstractThe optical anisotropy and orientaional behavior of dichroic dyes were investigated to better understand the effect of the molecular structure in a highly efficient polarizer. For this purpose, twenty novel dyes were synthesized, and PVA-dye polarizing films and guest-host coatable polarizers were prepared. The results in this study were analyzed in terms of the linearity, transition dipole moment, and affinity for host materials.
The linearity affects both the dichroic and the orientational behavior of the dyes. The linearity of dyes was modulated by the change of the positions of azo linkages and terminal substituents. A molecular structure with long and linear conjugation was geometrically advantageous for the anisotropic transition dipole moment and the high orientation order. The linearity was an important factor in guest-host coatable polarizers as well as PVA-based polarizing films.
The transition dipole moment is essential to ensure the selective absorbance and polarization of particular light frequencies. The anisotropic transition dipole moment was determined by the direction of charge transfer in conjugated system, and affected by the charge distribution modified by electron donating and withdrawing groups. High dichroic ratios required the charge transfer without electronic obstacles, the charge distribution without deviation from long-axis and abundant π-electrons for transfer.
The affinity for the host material is important as it governs the degree of molecular alignment and orientation. The affinity was influenced by the various intermolecular interactions according to the molecular structure of dyes. The intermolecular interactions were analyzed by the influences of van der Waals force, hydrogen bonding interaction, π-π interaction, electrostatic effect, hydrophilic/hydrophobic ratio, polarity and steric hindrance. Generally, van der Waals force and steric hindrance were the dominant factors for the affinity and orientation in both PVA-based polarizing films and coatable polarizers. In PVA-based polarizing films, the hydrogen bonding had a great effect on the affinity, whereas the polarity played an important role in coatable polarizers.
The dye concentration in host materials was a crucial factor determining the dichroic ratio of polarizers. To achieve a high dichroic ratio, the dye concentration should be the optimum amount in PVA-based polarizing films and should not exceed the permissible limit in guest-host coatable polarizers.		-
dc.description.tableofcontentsChapter 1.
Introduction 1
1.1 Polarizer and polarizing film 1
1.1.1 Manufacturing of PVA-based polarizing films 6
1.1.2 Two dichroic materials for PVA-based polarizing films 8
1.2 Coatable polarizer 12
1.2.1 Guest-host system 13
1.2.1.1 Types of liquid crystals 15
1.2.1.2 Alignment 17
1.2.2 Lyotropic chromonic liquid crystals (LCLCs) 19
1.3 Optical properties of the polarizer 21
1.3.1 Order parameter 22
1.4 Research objective 24
1.5 References 28

Chapter 2.
Effect of dye structure on dyeing and optical property of azo dichroic dyes for PVA polarizing film 33
2.1 Introduction 33
2.2 Experimental section 35
2.2.1 Materials and instrumentation 35
2.2.2 Synthesis of dye intermediates 36
2.2.2.1 Synthesis of dye intermediate (I1) 36
2.2.2.2 Synthesis of dye intermediate (I2, J-J acid) 36
2.2.3 Synthesis of dichroic dyes (Dye1–Dye4) 38
2.2.4 Preparation of polarizing films 41
2.2.5 Investigation of optical properties of polarizing films 42
2.3 Results and discussion 43
2.3.1 Synthesis and characterization of dichroic dyes 43
2.3.2 Dyeing of PVA film with dichroic dyes 47
2.3.3 Optical properties of the polarizing films 52
2.4 Conclusions 60
2.5 References 61

Chapter 3.
Dichroic and spectral properties of dichroic dyes with bichromophore for PVA polarizing film 65
3.1 Introduction 65
3.2 Experimental section 67
3.2.1 Materials and instrumentation 67
3.2.2 Synthesis of dyes 68
3.2.2.1 Synthesis of anthraquinone-based azo dyes 68
3.2.2.2 Synthesis of disazo dye 70
3.2.3 Preparation of polarizing films 74
3.2.4 Investigation of optical properties of polarizing films 74
3.2.5 Molecular orbital (MO) calculation 75
3.3 Results and discussion 76
3.3.1 Structure of synthesized dyes 76
3.3.2 Spectral properties of the dyes and PVA polarizing films 79
3.3.3 Dichroic properties of anthraquinone-based azo dyes in PVA polarizing films 83
3.3.4 Advantage for neutral gray 91
3.4 Conclusions 93
3.5 References 95

Chapter 4.
Effect of dye structure on orientational behavior and transition moments in guest-host coatable polarizer 98
4.1 Introduction 98
4.2 Experimental section 101
4.2.1 Materials and instrumentation 101
4.2.2 Synthesis of dyes 102
4.2.2.1 Synthesis of Dye 2 102
4.2.2.2 Synthesis of Dye 3 103
4.2.2.3 Synthesis of Dye 4 105
4.2.3 Fabrication of coatable polarizers 108
4.2.4 Investigation of optical properties of coatable polarizers 108
4.2.5 Theoretical calculation 109
4.3 Results and discussion 110
4.3.1 Structure and characterization of synthesized dyes 110
4.3.2 Characteristic of Guest-host coatable polarizers 114
4.3.3 Effect of dye structures on dichroic ratio 119
4.3.4 Transition dipole moment of dichroic dyes in Guest-host system 124
4.4 Conclusions 133
4.5 References 135

Chapter 5.
Optimized molecular structures of guest-host system for highly efficient coatable polarizer 142
5.1 Introduction 142
5.2 Experimental section 144
5.2.1 Materials and instrumentation 144
5.2.2 Synthesis of dyes 145
5.2.2.1 Synthesis of BP series 145
5.2.2.2 Synthesis of ST series 149
5.2.2.3 Synthesis of US series 151
5.2.3 Fabrication of coatable polarizers 152
5.2.4 Investigation of optical properties of coatable polarizers 152
5.2.5 Theoretical calculation 153
5.3 Results and discussion 154
5.3.1 Difference between 003-Host and 006-Host 154
5.3.2 Structure and characterization of dichroic dyes 158
5.3.3 Orientation of dichroic dyes within Host-003 164
5.3.4 Alignment of Host-006 doped with dyes 171
5.3.5 Dichroic properties of Host -006 doped with dyes 178
5.4 Conclusions 182
5.5 References 183

Summary 189		-
dc.formatapplication/pdf-
dc.format.extent3689768 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectDichroic dyes-
dc.subjectPVA-based polarizing film-
dc.subjectGuest-host system-
dc.subjectCoatable polarizer-
dc.subjectOrientation-
dc.subjectAlignment-
dc.subject.ddc620-
dc.titleA study on the optimized molecular structures for high dichroism and orientation in PVA-based polarizing films and guest-host coatable polarizers-
dc.title.alternativePVA계 편광필름과 코팅형 게스트-호스트 편광자에서 고이색성과 고배향이 가능한 최적분자구조에 관한 연구-
dc.typeThesis-
dc.description.degreeDoctor-
dc.citation.pagesxv, 196-
dc.contributor.affiliation공과대학 재료공학부-
dc.date.awarded2015-02-
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