此研究以向列型液晶–5CB為基礎，參雜了含有胺基的兩親性分子–PBA，開發了檢測水中甲醛的液晶感測器。由於PBA具有兩親性，可以在液晶／水溶液界面誘導液晶的排列形成垂直配向，在此狀態下以偏光顯微鏡可觀察到暗的光學訊號，當甲醛存在於系統時會與PBA發生反應，導致其結構由胺基變為亞胺基，失去誘導液晶排列的能力，此時液晶排列狀態改變並呈現亮訊號，由這個暗變亮的訊號轉換，我們可以得知系統是否檢測到水溶液中甲醛的存在。
起初我們以Hantzsch反應為檢測機制設計感測器，隨著進一步的討論，我們修改了對檢測機制的假說，並證明了其檢測機制為醛胺縮合反應，以此機制在酸性條件下，感測器可以檢測到1 mM的甲醛，具有高度的選擇性，也可應用於檢測化妝水樣品中30 mM濃度的甲醛含量。
液晶感測器具有低成本、簡單操作且肉眼即可辨識訊號的特性，因此適合開發為個人護理用品之甲醛檢測器。

We developed a liquid crystal (LC)-based sensor system for detecting formaldehyde in aqueous solutions. In this sensor, nematic LCs were doped with 4'-pentyl-4-biphenylamine (PBA), which acts as the amphiphilic molecule to align at LC/aqueous interface. Such alignment induced the homeotropic orientation of LCs and a dark signal was observed under polarized light. When formaldehyde was presented in the aqueous solutions, formaldehyde reacted with PBA to produce corresponding imine, which was not able to align at LC/aqueous interface such that the orientation of LCs was disrupted. As a result, a dark-to-bright transition of the LC signals was observed. 
    At first, we supposed the detection mechanism was involved Hantzsch reaction. Based on the evidences of each discussion, we discarded our hypothesis and proved that the mechanism was amine-aldehyde reaction. By using this mechanism, 1 mM of formaldehyde can be detected in real-time with good selectivity. Moreover, we demonstrated that this system can be applied to detect formaldehyde in commercial facial toners with the limit of detection (LOD) of 30 mM. Because the LC-based sensor system is cost-effective and easy to use, while its signals can be simply differentiated through the naked-eye under ambient light, it shows great potential for the applications of formaldehyde detection in the daily necessities for general family.

目錄
第一章 緒論	1
1-1液晶	1
1-1-1液晶的分類	2
1-1-2溶致型液晶	3
1-1-3熱致型液晶	3
1-1-4高分子液晶	4
1-1-5盤狀液晶	5
1-1-6桿狀液晶	5
1-1-7向列型液晶	7
1-1-8層列型液晶	7
1-1-9膽固醇液晶	9
1-2液晶感測器	9
1-2-1液晶感測器之檢測機制	10
1-2-2氣∕液相液晶檢測系統	11
1-2-3固相液晶檢測系統	15
1-2-4液晶液滴檢測系統	16
1-3甲醛	17
1-3-1甲醛對人體的危害	17
1-3-2甲醛檢測方法	18
1-3-2-1 Hantzsch Reaction檢測法	18
1-3-2-2 DNPH Reagent檢測法	19
1-4研究動機	20
第二章 實驗方法與材料	21
2-1實驗藥品與器材	21
2-2實驗儀器	22
2-3實驗方法	23
2-3-1製備PDMS培養皿	23
2-3-2製備DMOAP玻璃	23
2-3-3清洗TEM金屬網格（TEM-grid）	24
2-3-4製備參雜PBA之液晶	24
2-3-5製備1xPBS緩衝溶液	24
2-3-6製備醋酸鹽緩衝溶液	25
2-3-7製備不同濃度之CTAB溶液	25
2-3-8製備含有acetylacetone之待測液	25
2-3-9製備含有acetylacetone及甲醛之待測液	25
2-3-10製備甲醛待測液（不含acetylacetone）	26
2-3-11 PBA分子與甲醛反應性測試	26
2-3-11-1定量分析	26
2-3-11-2反應動力學測試	26
2-3-12 PBA分子之合成步驟	27
2-3-13以PBA進行Hantzsch Reaction之合成步驟	28
2-3-13-1 PBA與acetylacetone之反應	28
2-3-13-2甲醛與acetylacetone之反應	29
2-3-13-3甲醛、PBA與acetylacetone之反應	30
2-3-14以PBA進行醛胺縮合反應之合成步驟	31
第三章 結果與討論	32
3-1以Hantzsch Reaction作為檢測機制	32
3-1-1 Hantzsch Reaction之反應機制	33
3-1-2以PBA及CTAB控制液晶排列	34
3-1-3 Acetylacetone濃度對系統的影響	35
3-1-4系統對甲醛之偵測極限	35
3-1-5移除acetylacetone對系統的影響	36
3-1-6以PBA進行Hantzsch Reaction之可行性	37
3-1-7探討並修正對檢測機制之假說	38
3-2以醛胺縮合反應作為檢測機制	39
3-2-1醛胺縮合反應之反應機制	40
3-2-2 PBA-甲醛反應之可行性	40
3-2-3 PBA與不同濃度甲醛反應之吸收光譜變化	42
3-2-4 PBA-甲醛反應之動力學	44
3-2-5酸性條件下CTAB濃度對液晶訊號之影響	45
3-2-6酸性條件下系統對甲醛之偵測極限	45
3-2-7系統之選擇性探討	46
3-2-8系統對真實樣品的檢測結果	47
第四章 結論	49
參考資料	50
附圖	54
 
圖目錄
圖 1、Cholesteryl benzoate於不同溫度下所呈現之變化。	2
圖 2、液晶的分類。	3
圖 3、para-azoxyanisole, PAA之結構。	4
圖 4、常見主鏈／側鏈型高分子液晶。	4
圖 5、六取代–正–烷基氧醯基苯系列分子。	5
圖 6、典型桿狀液晶結構示意圖。	6
圖 7、向列型、層列型、膽固醇液晶之排列示意圖。	6
圖 8、層列型液晶SmA與SmC之排列示意圖。	8
圖 9、不同溫度範圍下8CB液晶相之變化。	8
圖 10、膽固醇液晶之螺距與光學性質示意圖。	9
圖 11、液晶感測器機制示意圖。	11
圖 12、氣∕液相液晶檢測系統裝置示意圖。	12
圖 13、(a) DMOAP及(b) OTS之結構。	13
圖 14、檢測氨氣氣體之機制示意圖。	14
圖 15、Hg2+檢測機制示意圖。	15
圖 16、液晶液滴之 (a) radial、(b) bipolar排列示意圖及偏光顯微鏡下呈現之光學訊號。	16
圖 17、DNPH與醛、酮類的反應。	19
圖 18、以Hantzsch Reaction設計之檢測機制示意圖。	32
圖 19、以PBA進行Hantzsch Reaction之反應機制。	33
圖 20、CTAB濃度對參雜PBA之液晶訊號影響。	34
圖 22、Acetylacetone濃度變化對液晶訊號影響。	35
圖 23、系統對甲醛之偵測極限。	36
圖 24、移除acetylacetone對系統的影響。	37
圖 25、以PBA進行Hantzsch Reaction之反應式	38
圖 26、以醛胺縮合為甲醛檢測機制之示意圖。	39
圖 27、PBA–甲醛縮合反應機制。	40
圖 28、PBA與MPBA在CDCl3之1H NMR光譜。	41
圖 29、MPBA之GC-MS光譜 (m/z = 253)。	42
圖 30、PBA與不同濃度甲醛反應之吸收光譜。	43
圖 31、PBA與甲醛之動力學研究。	44
圖 32、在酸性條件下CTAB濃度對液晶訊號之影響。	45
圖 33、酸性條件下系統對甲醛之偵測極限及訊號灰階值分析。	46
圖 34、系統之選擇性測試。	47
圖 35、系統對真實樣品檢測。	48
附圖目錄
附圖 1、PBA之1H NMR (CDCl3, 300 Hz)	54
附圖 2、4-((4'-pentyl-[1,1'-biphenyl]-4-yl)amino)pent-3-en-2-one之1H NMR (CDCl3, 300 Hz)	54
附圖 3、3-methylenepentane-2,4-dione之1H NMR (CDCl3, 300 Hz)	55
附圖 4、MPBA之1H NMR (CDCl3, 300 Hz)	55

1.	Shao, Y.; Zerda, T. W., Phase Transitions of Liquid Crystal PAA in Confined Geometries. The Journal of Physical Chemistry B 1998, 102 (18), 3387-3394.
2.	Taniguchi, N.; Nagai, K., Liquid Crystalline Polymers: Diffusion. Reference Module in Materials Science and Materials Engineering 2016.
3.	Chandrasekhar, S., NEW LIQUID CRYSTALLINE STATES. Current Science 1981, 50 (2), 47-49.
4.	Fernsler, J.; Wicks, D.; Staines, D.; Havens, A.; Paszek, N., Birefringence suppression near the smectic A–smectic C phase transition in de Vries-type liquid crystals. Liquid Crystals 2012, 39 (10), 1204-1215.
5.	Matsuhashi, N.; Kimura, M.; Akahane, T.; Yoshida, M., Structure analysis of 4-octyl-4'-cyanobiphenyl liquid-crystalline free-standing film by molecular dynamics simulation. Advances in Technology of Materials and Materials Processing Journal, 2006, 8 (2), 166-171.
6.	Zhang, L.-Y.; Gao, Y.-Z.; Song, P.; Wu, X.-J.; Yuan, X.; He, B.-F.;  Chen, X.-W.; Hu, W.; Guo, R.-W.; Ding, H.-J., Research progress of cholesteric liquid crystals with broadband reflection characteristics in application of intelligent optical modulation materials. Chinese Physics B 2016, 25 (9), 096101.
7.	Gupta, V. K.; Skaife, J. J.; Dubrovsky, T. B.; Abbott, N. L., Optical Amplification of Ligand-Receptor Binding Using Liquid Crystals. science 1998, 279 (5359), 2077-2080.
8.	Yang, S.; Wu, C.; Tan, H.; Wu, Y.; Liao, S.; Wu, Z.; Shen, G.; Yu, R., Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions. Anal. Chem. 2012, 85 (1), 14-18.
9.	Aliño, V. J.; Sim, P. H.; Choy, W. T.; Fraser, A.; Yang, K.-L., Detecting proteins in microfluidic channels decorated with liquid crystal sensing dots. Langmuir 2012, 28 (50), 17571-17577.
10.	Wei, Y.; Jang, C.-H., Optical imaging of cholylglycine by using liquid crystal droplet patterns on solid surfaces. J. Mater. Sci. 2016, 51 (4), 2033-2040.
11.	Chen, C.-H.; Yang, K.-L., Detection and quantification of DNA adsorbed on solid surfaces by using liquid crystals. Langmuir 2009, 26 (3), 1427-1430.
12.	Chuang, C.-H.; Lin, Y.-C.; Chen, W.-L.; Chen, Y.-H.; Chen, Y.-X.; Chen, C.-M.; Shiu, H. W.; Chang, L.-Y.; Chen, C.-H.; Chen, C.-H., Detecting trypsin at liquid crystal/aqueous interface by using surface-immobilized bovine serum albumin. Biosens. Bioelectron 2016, 78, 213-220.
13.	Zafiu, C.; Hussain, Z.; Küpcü, S.; Masutani, A.; Kilickiran, P.;  Sinner, E.-K., Liquid crystals as optical amplifiers for bacterial detection. Biosens. Bioelectron 2016, 80, 161-170.
14.	Munir, S.; Park, S.-Y., Liquid-crystal droplets functionalized with a non-enzymatic moiety for glucose sensing. Sens. Actuator B-Chem. 2018, 257, 579-585.
15.	Qi, L.; Hu, Q.; Kang, Q.; Yu, L., Fabrication of liquid-crystal-based optical sensing platform for detection of hydrogen peroxide and blood glucose. Anal. Chem. 2018, 90 (19), 11607-11613.
16.	Chen, C.-H.; Yang, K.-L., A liquid crystal biosensor for detecting organophosphates through the localized pH changes induced by their hydrolytic products. Sens. Actuator B-Chem. 2013, 181, 368-374.
17.	Chen, W.-L.; Ho, T. Y.; Huang, J.-W.; Chen, C.-H., Continuous monitoring of pH level in flow aqueous system by using liquid crystal-based sensor device. Microchemical Journal 2018, 139, 339-346.
18.	Niu, X.; Zhong, Y.; Chen, R.; Wang, F.; Luo, D., Highly sensitive and selective liquid crystal optical sensor for detection of ammonia. Opt. Express 2017, 25 (12), 13549-13556.
19.	Chen, C.-H.; Lin, Y.-C.; Chang, H.-H.; Lee, A. S.-Y., Ligand-doped liquid crystal sensor system for detecting mercuric ion in aqueous solutions. Anal. Chem. 2015, 87 (8), 4546-4551.
20.	Tejado, A.; Pena, C.; Labidi, J.; Echeverria, J.; Mondragon, I., Physico-chemical characterization of lignins from different sources for use in phenol–formaldehyde resin synthesis. Bioresour. Technol. 2007, 98 (8), 1655-1663.
21.	Lund, K. H.; Petersen, J. H., Migration of formaldehyde and melamine monomers from kitchen-and tableware made of melamine plastic. Food Addit. Contam. 2006, 23 (9), 948-955.
22.	Gindl, W.; Schöberl, T.; Jeronimidis, G., The interphase in phenol–formaldehyde and polymeric methylene di-phenyl-di-isocyanate glue lines in wood. Int. J Adhes. Adhes. 2004, 24 (4), 279-286.
23.	Kiss, C. R.; Huang, S.-J. W., Melamine-formaldehyde/styrene-acrylate paint detackification composition. Patents 1988.
24.	Rossmoore, H.; Sondossi, M., Applications and mode of action of formaldehyde condensate biocides. In Advances in applied microbiology, Elsevier: 1988, 33, 223-277.
25.	Travassos, A. R.; Claes, L.; Boey, L.; Drieghe, J.; Goossens, A., Non‐fragrance allergens in specific cosmetic products. Contact dermatitis 2011, 65 (5), 276-285.
26.	Bosetti, C.; McLaughlin, J.; Tarone, R.; Pira, E.; La Vecchia, C., Formaldehyde and cancer risk: a quantitative review of cohort studies through 2006. Ann Oncol. 2008, 19 (1), 29-43.
27.	Zhang, L.; Steinmaus, C.; Eastmond, D. A.; Xin, X. K.; Smith, M. T., Formaldehyde exposure and leukemia: a new meta-analysis and potential mechanisms. Mutat Res. 2009, 681 (2-3), 150-168.
28.	Wahed, P.; Razzaq, M. A.; Dharmapuri, S.; Corrales, M., Determination of formaldehyde in food and feed by an in-house validated HPLC method. Food Chem. 2016, 202, 476-483.
29.	Zhou, Y.; Yan, J.; Zhang, N.; Li, D.; Xiao, S.; Zheng, K., A ratiometric fluorescent probe for formaldehyde in aqueous solution, serum and air using aza-cope reaction. Sens. Actuator B-Chem. 2018, 258, 156-162.
30.	Chaiendoo, K.; Sooksin, S.; Kulchat, S.; Promarak, V.; Tuntulani, T.; Ngeontae, W., A new formaldehyde sensor from silver nanoclusters modified Tollens’ reagent. Food Chem. 2018, 255, 41-48.
31.	Wang, X.; Si, Y.; Wang, J.; Ding, B.; Yu, J.; Al-Deyab, S. S., A facile and highly sensitive colorimetric sensor for the detection of formaldehyde based on electro-spinning/netting nano-fiber/nets. Sens. Actuator B-Chem. 2012, 163 (1), 186-193.
32.	Wang, X.; Si, Y.; Mao, X.; Li, Y.; Yu, J.; Wang, H.; Ding, B., Colorimetric sensor strips for formaldehyde assay utilizing fluoral-p decorated polyacrylonitrile nanofibrous membranes. Analyst 2013, 138 (17), 5129-5136.
33.	Jia, X.; Zhang, T.; Wang, J.; Wang, K.; Tan, H.; Hu, Y.; Zhang, L.; Zhu, J., Responsive photonic hydrogel-based colorimetric sensors for detection of aldehydes in aqueous solution. Langmuir 2018, 34 (13), 3987-3992.
34.	Baghbanian, S. M.;  Khaksar, S.;  Vahdat, S. M.;  Farhang, M.; Tajbakhsh, M., One-step, synthesis of Hantzsch esters and polyhydroquinoline derivatives using new organocatalyst. Chin. Chem. Lett 2010, 21 (5), 563-567.
35.	Nash, T., The colorimetric estimation of formaldehyde by means of the Hantzsch reaction. Biochem. J. 1953, 55 (3), 416-421.
36.	Castell, C.; Smith, B., Measurement of formaldehyde in fish muscle using TCA extraction and the Nash reagent. J. Fish Res. Board Can. 1973, 30 (1), 91-98.
37.	Ogasawara, N.; Misaki, M.; Adachi, S., Method for the determination of residual formaldehyde in an inactivated Zika vaccine formulated with aluminum hydroxide gel. Biologicals 2019, 58, 73-75.
38.	Alvim, H. G. O.; da Silva Júnior, E. N.; Neto, B. A. D., What do we know about multicomponent reactions? Mechanisms and trends for the Biginelli, Hantzsch, Mannich, Passerini and Ugi MCRs. RSC Adv. 2014, 4 (97), 54282-54299.
39.	Sprung, M. A., A Summary of the Reactions of Aldehydes with Amines. Chem. Rev. 1940, 26 (3), 297-338.