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研究生:陳威州
研究生(外文):Chen, Wei-Jou
論文名稱:含液晶滴之聚合物形成過程的動態模擬
論文名稱(外文):Simulation on the Kinetic Process in Polymer-Dispersed Liquid Crystals
指導教授:王淑霞
指導教授(外文):Shu-Hsia Chen
學位類別:博士
校院名稱:國立交通大學
系所名稱:光電(科學)研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:1995
畢業學年度:84
語文別:英文
論文頁數:111
中文關鍵詞:含液晶滴之聚合物凝膠化轉變高分子聚合誘發相分離
外文關鍵詞:Polymer-dispersed liquid crystalsSol-gel erization-induced phase separation
相關次數:
  • 被引用被引用:0
  • 點閱點閱:199
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  • 下載下載:0
  • 收藏至我的研究室書目清單書目收藏:1
本論文研究含液晶聚合物形成過程。在一般條件下,含液晶聚合物是由起
初均勻混合的液晶分子與聚合物單體分子,在一連串的高分子聚合化學反
應下誘發液晶分子與高分子分離而形成的。其形成過程是一高分子聚合誘
發相分離的過程。而在液晶分子與聚合物單體分子具有高粘滯係數或高分
子聚合化學反應極快速的條件下,含液晶聚合物的形成過程可視為一在具
有固定不動的非等向性液晶分子中的高分子聚合過程。首先,我們考慮在
含液晶聚合物的形成過程中,液晶分子與聚合物單體分子具有高粘滯係數
或高分子聚合化學反應極快速的條件下,提出一高分子在固定不動的非等
向性液晶分子中的聚合糢型。從這模型的研究,我們發現在非等向性液晶
的有序參數不為零的條件下,聚合成的網狀高分子同樣具有非等向性的結
構,此結果與最近在實驗上用電子顯微鏡所觀測的結果相符。此外,我們
得到此系統可凝膠化與不可凝膠化的相圖。利用有限尺寸的尺度分析,來
分析高分子的平均分子量,凝膠化程度及迴旋半徑,我們發現此一高分子
聚合模型在凝膠化轉變的臨界指數與滲透模型是一樣的。進一步,在一般
的條件下,即液晶分子與聚合物單體分子可適度流動,我們提出另外一個
模型來研究高分子聚合誘發相分離的過程。此一模型的研究,可得到實驗
上所觀測到的結構參數凍結現象。從動態結構參數的尺度分析中,我們得
到一動態尺度律,此一尺度律與熱致相分離研究所得的尺度律相同,並與
最近實驗所得相符。此外,此模型可由一組尺度律來分析高分子誘發相分
離的凍結結構及達到此凍結結構的時間與起始劑濃度的關係。我們提出一
理論分析而得此尺度律的指數並與模擬結果相符。從液晶分子團的尺寸分
析,我們還發現了在實驗上觀察到的二次相分離現象。
The subject of this thesis is to investigate the formation
process of a polymer-dispersed liquid crystals (PDLC). In
general, PDLC materials are formed from the phase separation
derived by chemical polymerization of an initially homogeneous
mixture of liquid crystals and monomers. The formation process
is referred to as a process of polymerization-induced phase
separation. For polymerization with fast reaction rate or the
molecules of liquid crystal and monomer with high viscosity,
the formation process of PDLC is regarded as a process of
polymerization in a quenched anisotropic nematic medium. First,
we propose a model to study the polymerization in a quenched
anisotropic nematic solvent for the system in which the time
scale for polymerization is short compared to that for the
mobility of the anisotropic nematic solvent or monomers. The
structure of a polymer network was found to be extended in the
direction of the director of the anisotropic nematic solvent,
as the order parameter of the anisotropic nematic solvent is
nonzero. The experimental observation of scanning electron
micrograph is consistent with our simulation results. In
addition, we construct a phase diagram of gel-nongel for the
kinetic gelation system. Finite-size scaling analyses for the
average molecular weight, gel fraction, and radii of gyration
show that the critical exponents of the sol-gel transition is
the same as that of percolation. Furthermore, we propose a
dynamical model to study the polymerization-induced phase
separation for taking into account the mobile behavior of a
liquid crystal and a monomer. A pinning phenomenon of the
structure factor was found and consistent with experimental
observation. The time evolution of the structure factor was
found to preserve the scaling law obtained from the thermally
quenched phase separation as well as the recent experiment. In
addition, The model leads to the revelation of scaling
relations of pinned structure factor and crossover time with a
Cover
Chinese Abstract
English Abstract
Acknowledgment
List of Figures
List of Symbols
Chapter I General Introduction
I.I An overview of polymer-dispersed liquid crystals
1.2 Historical review of study on polymerization and phase separation
1.2.1 Polymerization
1.2.2 Phase separation
1.3 Thesis content
Chapter 2 Addition Polymerization in a Nematic Medium
2.1 Introduction
2.2 Model and method
2.3 Results
2.3.1 Trapping effects and gel-nongel phase diagram
2.3.2 Finite-size scaling and critical behavior
2.3.3 Anisotropic solvent effects
2.4 Conclusion
Chapter 3 Dynamical Scaling of Polymerization-Induced Phase Sepa ration
3.1 Introduction
3.2 Model and method
3.3 Results
3.3.1 Pinning phenomenon
3.3.2 Dynamical scaling of the structure factor
3.3.3 Peaking of mean cluster size of solvent molecules
3.4 Discussion
3.5 Conclusion
Chapter 4 Pinning in Polymerization-Induced Phase Separation
4.1 Introduction
4.2 Model and method
4.3 Results
4.3.1 Scaling analysis of pinning behavior
4.4 Theory
4.5 Discussion
4.6 Conclusion
Chapter 5 Summary and Future Research Directions
References
Appendix A Simulation Algorithms and Prograins
A.I Program for kinetic gelation in a quenched rodlike anisotropic nematic medium
A.2 Program for polymerization-induced phase separation
Resume
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