本實驗目的在於將具有螢光感測能力之共聚高分子製成靜電紡絲奈米纖維，並將其應用於苦味酸之感測。靜電紡絲(electrospinning)為近年來用於製備多功能高分子纖維的新技術，以靜電紡絲技術製成的纖維尺寸達奈米等級，相較於微米等級的纖維或薄膜型態，奈米纖維具有較高的比表面積(surface-to-volume ratio)，因此被廣泛的應用在感測器上。本實驗先使用Suzuki coupling reaction，合成具有螢光基團的4-(1-Pyrenyl)styrene (St-Py)單體，再利用自由基聚合法(free radical polymerization)合成不同螢光基團比例之共聚高分子poly{(N-isopropylacrylamide)-co-(N-hydroxymethyl acrylamide)-co-[4-(1-pyrenyl)-styrene]a} [poly(NIPAAm-co-NMA-co-St-Py)，PNNS1、PNNS2、PNNS3]，並藉由靜電紡絲技術將其製成奈米纖維薄膜，共聚高分子中的NIPAAm為具有溫度敏感性質之單體，使纖維具有收縮-膨潤之特性，而NMA為可化學交聯單體，經由加熱交聯後能使纖維形態在溶液中維持穩定。感測方面以4-(1-Pyrenyl)styrene (St-Py)中的pyrene為螢光基團，當pyrene受激發後會與周圍的苦味酸產生電子轉移並產生螢光淬滅。本實驗將共聚高分子分別以溶液、薄膜、奈米纖維薄膜形態對苦味酸進行感測，在不同苦味酸濃度下量測螢光光譜後，使用Stern-Volmer plot以及ratiometric measurements分析比較各種形態之感測特性。另外以場效發射式掃描電子顯微鏡(FE-SEM)觀察纖維的形態變化，發現交聯前後纖維直徑沒明顯改變，泡水後纖維因膨潤有直徑有擴大的現象，但因為共聚高分子在交聯後不溶解於水溶液而能維持住纖維形態。

Random copolymers [poly (NIPAAm-co-NMA-co-St-Py)], functionalized with pyrene moieties, were prepared by free radical copolymerization. The nanofibers of copolymers were obtained by electrospinning technique and used to detect picric acid (PA) through photo-induced electron transfer (PET) mechanism. The sensing performance of pyrene-functional random copolymers was investigated and compared in three different states, solution, film and nanofiber film. In addition, the fiber morphology was observed by field emission scanning electron microscopy (FE-SEM), which show that the nanofibers with diameter of 179±28 and did not change significantly before and after cross-linking.

1. Sun, X., et al., Fundamental Study of Electrospun Pyrene-Polyethersulfone Nanofibers Using Mixed Solvents for Sensitive and Selective Explosives Detection in Aqueous Solution. ACS Appl Mater Interfaces, 2015. 7(24): p. 13189-97.
2. Zukas, J.A. and W.P. Walters, Explosive Effects and Applications
3. Cammann, B.K., Chemical Sensors and Biosensors-Principles and Applications. 1991. p. 516-539.
4. Valeur, B., Molecular Flurescence.Principles and Application
5. Fraiji, L.K. and T. C.wernerl, Static and Dynamic Fluorescence Quenching Experiments for the Physical Chemistry Laboratory. 1992.
6. ATF, Fed. Regist. 2010. 75.
7. O¨stmark, H., S. Wallin, and H.G. Ang, Propellants, Explos.,Pyrotech. Vol. 37. 2012. p.12–23.
8. Kolla, P. Anal. Chem. Vol. 67. 1995.
9. Ponnuvel, K., G. Banuppriya, and V. Padmini, Highly efficient and selective detection of picric acid among other nitroaromatics by NIR fluorescent organic fluorophores. Sensors and Actuators B: Chemical, 2016. 234: p. 34-45.
10. Peng, Y., et al., A colorimetric and fluorescent chemosensor for the detection of an explosive--2,4,6-trinitrophenol (TNP). Chem Commun (Camb), 2011. 47(15): p. 4505-7.
11. Sun, X., Y. Wang, and Y. Lei, Fluorescence based explosive detection: from mechanisms to sensory materials. Chem Soc Rev, 2015. 44(22): p. 8019-61.
12. Liu, X., Y. Xu, and D. Jiang, Conjugated microporous polymers as molecular sensing devices: microporous architecture enables rapid response and enhances sensitivity in fluorescence-on and fluorescence-off sensing. J Am Chem Soc, 2012. 134(21): p. 8738-41.
13. Feng, L., et al., Detection of TNT based on conjugated polymer encapsulated in mesoporous silica nanoparticles through FRET. Chem Commun (Camb), 2012. 48(38): p. 4633-5.
14. Senthamizhan, A., et al., Highly Fluorescent Pyrene-Functional Polystyrene Copolymer Nanofibers for Enhanced Sensing Performance of TNT. ACS Appl Mater Interfaces, 2015. 7(38): p. 21038-46.
15. Beyazkilic, P., A. Yildirim, and M. Bayindir, Formation of pyrene excimers in mesoporous ormosil thin films for visual detection of nitro-explosives. ACS Appl Mater Interfaces, 2014. 6(7): p. 4997-5004.
16. Du, H., et al., Preparation of pyrene-functionalized fluorescent film with a benzene ring in spacer and sensitive detection to picric acid in aqueous phase. Journal of Photochemistry and Photobiology A: Chemistry, 2011. 217(2-3): p. 356-362.
17. Guo, L., et al., APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection. Nanoscale, 2014. 6(3): p. 1467-73.
18. Stuart, M.A., et al., Emerging applications of stimuli-responsive polymer materials. Nat Mater, 2010. 9(2): p. 101-13.
19. Weber, C., R. Hoogenboom, and U.S. Schubert, Temperature responsive bio-compatible polymers based on poly(ethylene oxide) and poly(2-oxazoline)s. Progress in Polymer Science, 2012. 37(5): p. 686-714.
20. Rzaev, Z.M.O., S. Dinçer, and E. Pişkin, Functional copolymers of N-isopropylacrylamide for bioengineering applications. Progress in Polymer Science, 2007. 32(5): p. 534-595.
21. Chiu, Y.C., et al., Synthesis, morphology, and sensory applications of multifunctional rod-coil-coil triblock copolymers and their electrospun nanofibers. ACS Appl Mater Interfaces, 2012. 4(7): p. 3387-95.
22. Huglin, M.B. and M.A. Radwan, Comparison of the thermal behaviour of aqueous solutions and hydrogels of poly(N-methylol acrylamide). 1991. 32.
23. Bubel, K., et al., Tenside-Free Biodegradable Polymer Nanofiber Nonwovens by “Green Electrospinning”. Macromolecules, 2013. 46(17): p. 7034-7042.
24. Martwiset, S., S. Nijpanich, and A. Banturngsaksiri, Pyrene-Doped Electrospun PMMA-PVC Fibers for Ferric Ion Detection. J. APPL. POLYM. SCI, 2013.
25. Li, D. and Y. Xia, Electrospinning of Nanofibers: Reinventing the Wheel?†. 2004: p. p. 1151-1170.
26. Jun, Z., H. Hou, and A. Schaper, Poly-L-lactide nanofibers by electrospinning –Influence of solution viscosity and electrical conductivity on fiber diameter and fiber morphology. 2003.
27. Fong, H., I. Chun, and D.H. Reneker, Beaded nanofibers formed during electrospinning. 1999.
28. Deitzel, J.M., J. Kleinmeyer, and D. Harris, The effect of processing variables on the morphology of electrospun nanofibers and textiles. Polymer, 2001.
29. Mit-uppatham, C., M. Nithitanakul, and P. Supaphol, Ultrafine Electrospun Polyamide-6 Fibers: Effect of Solution Conditions on Morphology and Average Fiber Diameter. Macromolecular Chemistry and Physics, 2004. 205(17): p. 2327-2338.
30. Casper, C.L., et al., Controlling Surface Morphology of Electrospun Polystyrene Fibers: Effect of Humidity and Molecular Weight in the Electrospinning Process. Macromolecules, 2004.
31. Miyaura, N. and A. Suzuki, Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chem. Rev, 1995. 95.