無機層狀材料奈米混成於高分子穩定膽固醇液晶之光電性質探討

Study on Electro-optical Properties of Polymer Stabilized Cholesteric Liquid Crystals by Hybridizing Inorganic Layered Materials

李淑慧(Shu-Hui Lee)

指導教授 ： 蔡宗燕 ； 徐芝珊

中原大學/理學院/化學研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700696

摘要

本研究主要探討向列型液晶中添加一或兩種不同旋性劑混合成膽固醇液晶 (Cholesteric liquid crystal, CLC)，製備出具電致變色能力的高分子穩定膽固醇液晶奈米複材(Polymer stabilized cholesteric liquid crystal, PSCLC/nano composites)，其組成包含向列型液 E7、左旋性劑 S811 或右旋性劑 R5011、光敏感高分子 NOA65 、無機層狀材料。無機層狀材料分為天然黏土層狀材料 (Clay) 及人工合成層狀材料 (LDHs)。利用具有苯環結構之電活性苯胺五聚體 (Pentamerous oligo-aniline, POA) 對天然黏土做有機改質。以微量無機層狀材料作為添加材摻雜於 PSCLC。另外探討紫外光照光時間、照光強度、光敏感高分子濃度對 PSCLC 的影響。實驗中利用廣角X光繞射光譜儀 (Wide Angle X-Ray Diffraction, WXRD)、傅立葉轉換紅外線光譜儀(Fourier Transform Infrared, FT-IR) 及熱失重分析儀 (Thermogravimetry Analyzer, TGA ) 對有機化改質型黏土進行結構鑑定。接著在外加交流電電場1 kHz下，量測閾值電壓、驅動電壓、反應時間等對光電特性之影響。並利用偏光顯微鏡 (Polarizing Optical Microscope, POM) 觀察 PSCLC 在無機層材的添加後，施加不同電壓後的顯色型態變化。依據實驗結果得知以光敏感高分子濃度較低，樣品PSCLC (R/2.5) 及紫外光照光強度較低，約2.2 mW/cm2 照射 10 min的PSCLC有較低的閾值電壓或驅動電壓。其未摻雜天然黏土的PSCLC (RS/2.5) 及摻雜不同天然黏土的CL42、CL120、CL88的驅動電壓分別為77.3、74.6、82.9、96.3 Vrms，得知 CL42 摻雜於PSCLC (RS/2.5)中，有效降低驅動電壓。而未摻雜人工合成黏土的PSCLC (RS/2.5) 及摻雜不同人工合成黏土的 MgAl-LDH、ZnAl-LDH、LiAl-LDH 之驅值電壓分別為77.3、71.0、77.5、84.8 Vrms ，得知MgAl-LDH有效降低驅值電壓。於反應時間中，也以 CL42 及 MgAl-LDH 擁有較快的反應時間，分別為3.75 ms 及4.31 ms。 利用式差掃描量熱儀 (Differential scanning calorimetry, DSC) 測量膽固醇液晶的相轉變溫度，添加具有高螺旋扭曲力的右旋性劑R5011之CLC，其膽固醇液晶相範圍較廣且溫度穩定性佳，從39°C提升到56.18°C。另外探討 CL42 摻雜於 PSCLC (R/2.5) 系統中，得知隨著 CL42 摻雜量的提升，其驅動電壓由76.6 Vrms有些微降低至76.1 Vrms 及有效的降低於 75 Vrms 之反應時間約42.6% (105.55 ms到60.6 ms )。以 XRD 證明摻雜無機層材 CL42 可增加液晶排列整齊而提升其結晶性，因此在驅動電壓與反應時間方面可改善PSCLC的光電特性。另外在POM觀察下，樣品天然黏土PSCLC (RS/2.5)-CL120與改質型黏土PSCLC (R/2.5)-CL120-POA、PSCLC (R/2.5)-CL42-POA有團聚現象，因此造成無法有效改善驅動電壓。以穩定性測試得知PSCLC (R/2.5)-CL42 1.0 phr有較穩定的狀態結果，穩定偏差範圍從 1.8 降至0.7 Vrms。

關鍵字

無機層狀材料 ； 高分子穩定膽固醇液晶 ； 電活性寡聚物 ； 奈米複合材料

並列摘要

In this research work, cholesteric liquid crystal (CLC) containing a nematic liquid crystal dispersed with one or two different chiral dopant and polymer stabilized cholesteric liquid crystal (PSCLC) were investigated. Further, One type of PSCLC/inorganic layered material nanocomposites has been synthesized by using electrochromic PSCLC, including nematic liquid crystal E7, left-hand twist (LT) chiral dopant S811, right-hand twist (RT) chiral dopant R5011, photocurable monomer NOA65 and inorganic layered materials. The inorganic layered materials are classified into natural layered clay material and synthetic layered double hydroxides (LDHs). The electroactive Pentamerous oligo- aniline (POA) used as a organo modifier for natural inorganic layered materials modification. The small amount of inorganic layered materials are doped into the PSCLC. The effects, which were caused by time of polymerization, intensity of polymerization and the concentration of photo- curable monomer on PSCLC were also investigated. The morphology and structural identification of organo modified inorganic layered materials identified by Wide Angle X-Ray Diffraction (WXRD), Fourier Transform Infrared (FT-IR) and Thermo- gravimetry Analyzer (TGA). PSCLC optical properties including threshold voltage, drive voltage, response time under 1 kHz AC electric field measured. The colour and morphology change of inorganic layered materials doped PSCLC observed by Polarizing Optical Microscope (POM) at different applied voltage. According to the experimental results, it was found that PSCLC had a lower threshold voltage or driving voltage with a lower concentration of photocurable monomer, PSCLC (RS/2.5) showed the lower intensity of polymerization about 2.2 mW/cm2 for 10 minutes. The PSCLC (RS/2.5) without doped natural layered clay and with doped CL42, CL120, CL88 driving voltage were 77.3, 74.6, 82.9 and 96.3 Vrms, respectively. It was found that CL42 doped PSCLC (RS/2.5) can effectively provide reducing the driving voltage. The PSCLC (RS/2.5) without doped LDHs and with doped MgAl-LDH、ZnAl-LDH、LiAl-LDH the driving voltage were 77.3、71.0、77.5 and 84.8 Vrms, respectively. It shown that MgAl-LDH in PSCLC (RS/2.5) can effectively reduce the driving voltage. The faster response time of CL42 (3.75 ms) and MgAl-LDH (4.31 ms) the better reducing the driving voltage. The phase transition temperature of cholesteric phase measured by differential scanning calorimetry (DSC), the CLC containing chiral dopant R5011 with helical twisting power (HTP) had wide temperature range for cholesteric phase and good in temperature stability, increasing from 39°C to 56.18°C. Additionally, CL42 doped PSCLC (R/2.5), the driving voltage decreased slightly from 76.6 Vrms to 76.1 Vrms with the increase of the CL42 doping amount, and the response time effectively reduced about 42.6% (105.55 ms to 60.6 ms) under 75 Vrms. It is proved that due to doped inorganic material CL42 can increase the crystallinity of liquid crystal and suppress the ionic impurities. Hence, resulting the optical properties of PSCLC can be improved in driving voltage and response time. In addition, from POM analysis, it is observed that natural clay PSCLC (RS/2.5)-CL120 and modified clay PSCLC (R/2.5)-CL120-POA, PSCLC (R/2.5)-CL42-POA showes the aggregation morphology. Thus it’s make the driving voltage can’t effectively improve. The stability test shows that CLC (R/2.5)-CL42 1.0 phr has a more stable state result, the stability deviation from 1.8 to 0.7 Vrms.

並列關鍵字

Inorganic layered materials ； PSCLC ； Electroactive oligomer ； Nanocomposites

參考文獻

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