層狀無機材料在高分子分散液晶之光電特性應用與奈米複合材之製備

Application of Layered Inorganic Materials in Rectification of Electro-optical Properties of Polymer-dispersed Liquid Crystals and Preparation of Penta-aniline/Clay Nanocomposites

李俊毅(Chun-Yi Lee)

指導教授 ： 蔡宗燕

中原大學/理學院/化學研究所/博士(2012年)

https://doi.org/10.6840/cycu201200196

摘要

本研究主要針對高分子分散液晶(polymer-dispersed liquid crystal, PDLC)薄膜的液晶球滴型態與光電效應之探討。其薄膜組成為向列型液晶E7、光敏感型高分子NOA65與不同無機奈米粒子，以365 nm紫外光照射樣品進行光聚合相分離法(photopolymerization-induced phase separation)形成液晶球滴於高分子中。無機奈米粒子分別為天然蒙脫土(CL42, CL120, CL88)和二氧化鈦(UV100)摻雜於PDLC中並外加適當電場量測光電特性。廣角X-ray繞射儀(wide angle X-ray diffraction, XRD)可以檢測無機奈米粒子於PDLC中的分散性與增加E7於混合液中的結晶性。液晶滴的型態以電子掃描顯微鏡(scanning electron microscope, SEM) 觀察摻雜PDLC樣品其粒徑大小與均一性會隨著添加量增加而增加。穿透式電子顯微鏡(transmission electron microscopy, TEM)與變溫XRD證明蒙脫土存在於高分子與液晶滴中。CL120最適當摻雜濃度為3 wt%於PDLC中可以降低驅動電壓約45.4% (64.92 Vrms到35.45 Vrms)和閾值電壓約25.0% (9.43 Vrms到7.07 Vrms)並改善光學特性如 τon 降低約34.6% (4.56 ms到2.98 ms)，提升對比度(contrast rate, CR)約182.2% (4.05 到11.43)。
以蒙脫土CL120改質苯胺五聚體(POA)於層間並以硫酸質子化POA形成導電態的emeraldine salt (ES) form成為功能型導電層狀材料。POA/CL120改質蒙脫土以XRD觀察POA插入後蒙脫土造成層間距撐開距離並以FTIR (Fourier transform infrared)鑑定改質蒙脫土層間之有機與無機的官能基，證明POA改質於蒙脫土層間及其氧化還原形態。以高解析度TGA對於改質蒙脫土中的POA定量，鑑定改質劑於存在於蒙脫土層間的數量，換算出POA於層間之理論插層率。根據上述可以證明POA成功改質於蒙脫土中，並控制質子化的pKa值引導POA插入於層間形成摻層型或脫層型分散。將POA-1/CL120改質蒙脫土摻雜於PDLC中，以適當1 wt%摻雜濃度與未摻雜之PDLC樣品相比較可以降低驅動電壓70% (64.92 Vrms到19.29 Vrms)，增加CR 500% (4.05 到21.39)，降低瞬態時變光電特性的升起時間於25 Vrms達0.7 ms，以及在不同的入射角和200 Vrms外加電場下與未摻雜樣品相似的光穿透度。

關鍵字

層狀材料 ； 苯胺五聚體 ； 高分子分散液晶 ； 奈米複合材

並列摘要

The morphology and the electro-optical properties of polymer-dispersed liquid crystals (PDLC) were performed in this study. These consist of nematic liquid crystal (LC) E7 filled with different types of inorganic nanoparticles in norland optical adhesive (NOA65) polymer matrices. The PDLC film is prepared by the photopolymerization-induced phase separation (PIPS) method using UV light irradiation at 635 nm. Natural clay CL42, CL120, CL88, and titanium dioxides UV-100 are used as nanofillers in the PDLC film through application filed. Wide angle X-ray diffraction (XRD) is used to learn the dispersion of the inorganic nanoparticles in the PDLC and improved the crystalline of E7 in the mixture. The morphology of LC droplets in the hybridization PDLC film was larger and more uniform than an undoping comparison by loading of increased with the diagram of scanning electron microscope (SEM). The clay is existed in the LC droplets and polymer by the transmission electron microscopy (TEM) and temperature dependence WAXD. It has been observed that the appropriate doping of 3 wt% of CL120 in PDLC can effectively reduce the driving (threshold) voltage and improve the optical properties. The threshold voltage, driving voltage, τon, and contrast rate are improved 45.4% (from 64.92 Vrms to 35.45 Vrms), 25.0% (from 9.43 Vrms to 7.07 Vrms), 34.6% (from 4.56 ms to 2.98 ms), and 182.2% (from 4.05 to 11.43), respectively.
In the other hand, a montmorillonite CL120 was studied via pentamerous oligo-aniline (POA), which was protonated with a sulfuric acid to emeraldine salts (ES) form, intercalating to form a functional conductive organo-layered material. The characteristics of modified clay—POA/CL120 identified exhaustive by XRD for the d-spacing of the montmorillonite layer, Fourier transform infrared (FTIR) for the oligoaniline and montmorillonite function group, and high-resolution thermogravimetric analyzer (TGA) for the theoretical intercalation capacity of the modified agent in the clay. Therefore, it successfully intercalated the POA into the montmorillonite by ionic exchange reaction and controlled the type dispersion of the modified clay with commanding the pKa of a protonated solution. PDLC composites were prepared from the modified clay loading in the matrix. There is no denying that improves in the electro–optical properties of PDLCs, which hybridization of POA-1/CL120 at 1wt% used in this work, lowers driving voltage by almost 70% ( from 64.92 Vrms to 19.29 Vrms), increases transmission of contrast ratio by 500% (from 4.05 to 21.39), rapid polarizes the LC directors at 25 Vrms by 0.7 ms, and approaching to the undoped PDLC of view angle at 200 Vrms in manner that depends on applied field.

並列關鍵字

Layered materials ； nanocomposites ； PDLC ； penta-aniline

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