Poly(NIPAM)/甲醇溶液及MEH-PPV/THF溶液物理性質

Physical Properties of Poly(N-isopropylacrylamide)/methanol Semi-dilute Solution and Poly[1-Methoxy-4-(2’-Ethyl-Hexyloxy)-2,5-Phenylene Vinylene]/ Tetrahydrofuran Solution

童翔駿(Hsiang-Chun Tung)

指導教授 ： 余子隆

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

本論文利用動態光散射及動態黏彈儀研究將5 wt%聚異丙基丙烯醯胺(poly(N- isopropyl acrylamide)，簡稱poly(NIPAM))/甲醇溶液物理性質。由極限黏度數據得知其重疊濃度C*~ 1 / [η]為約3.012 wt%，所以此溶液為半稀釋溶液 (semidilute solution)。由流變儀量測數據得知poly(NIPAM) /甲醇溶液的黏度隨著溫度的增加而下降，與一般高分子溶液現象相同。所以poly(NIPAM)/甲醇溶液是UCST (upper critical solution temperature)與poly(NIPAM)/水溶液的LCST (lower critical solution temperature)現象相反。動態光散射數據可得知poly(NIPAM)在甲醇溶液中的運動鬆弛時間(relaxation time)隨著散射角增加而逐漸下降。而相關長度ζ不會隨著溫度上升變化。此現象與poly(NIPAM) /水溶液的性質不同。一般文獻報告poly(NIPAM)在水溶液中，在溫度低於LCST(~ 34 ℃)下，poly(NIPAM)的支鏈-CO-NH-CH-(CH3)2與水分子因氫建結合可溶於水中，分子鏈形成coil狀態。隨著溫度上升，因氫鍵解離，水分子逐漸脫離poly(NIPAM)，使poly(NIPAM)分子不易溶於水中。而由coil態粒徑逐漸收縮轉變成球(globule)狀態。因此溫度上升，poly(NIPAM)/水溶液黏度會下降，而在溫度高於UCST以上，poly(NIPAM)/水溶液會有“相分離”(phase separation)現象發生。本研究報告顯示poly(NIPAM)在甲醇溶液中無如同poly(NIPAM) /水溶液之現象發生。poly(NIPAM)/甲醇溶液是屬於一般的高分子良溶液(polymer good solution)。
本論文研究0.2 ~ 1.5 wt%聚[1-甲氧基-4-(2’-乙基-己氧基)-2,5-苯乙烯]，( (poly[1-methoxy-4-(2’-ethyl-hexyloxy)-2,5-phenylene vinylene]，簡稱 MEH-PPV))以四氫呋喃(tetrahydrofuran，THF)溶液中MEH-PPV聚合物的分子形態，以及其對旋轉塗佈薄膜表面形態之影響。我們使用Ubbelohde黏度計及動態光散射研究溶液性質，由極限黏度數據得知MEH-PPV/THF溶液的重疊濃度C*為0.706 。動態光散射實驗數據得知MEH-PPV濃度增加，粒徑在0.6 wt%以下變化不大，但MEH-PPV濃度大於0.7 wt%，則粒徑明顯變大。MEH-PPV/THF溶液經旋轉塗佈薄膜，表面形態以原子力顯微鏡(AFM)觀察可知MEH-PPV濃度較低時，聚合物粒子呈不連續分佈，薄膜表面有明顯的高低起伏波峰。隨著MEH-PPV濃度增加，薄膜表面高低起伏度下降。MEH-PPV濃度高於0.7 wt%以上，薄膜表面形態較為平坦，顯示分子鏈互相重疊。

關鍵字

聚異丙基丙烯醯胺 ； 聚[1-甲氧基-4-(2’-乙基-己氧基)-2 ； 5-苯乙烯] ； 動態光散射 ； 原子力顯微鏡

並列摘要

In this thesis, using dynamic light scattering and dynamic viscoelastic analyzer, we studied the physical properties of 5 wt% poly(NIPAM) (poly(N- isopropyl acrylamide) -methanol solution. The overlap concentration C*, obtained from intrinsic viscosity measurement, was around 3.01 wt%. Thus the present solution is a semidilute solution. The viscosity of poly(NIPAM) -methanol solution decreases with increasing temperature, which behaves similar to the ordinary polymer good solutions with a USCT (upper critical solution temperature). The dynamic light scattering experiment result revealed that the relaxation time decreases with increasing scattering angles. But the correlation length does not vary with increasing temperature. The properties of poly(NIPAM) -methanol solution are different from those of poly(NIPAM) -water solution.
The molecular conformation of MEH-PPV (poly[1-methyoxy-4- (2’-ethyl-hexyloxy)-2,5-phenylene vinylene]) in THF (tetrahydrofuran) solutions with MEH-PPV concentrations ranging 0.2 ~ 1.5 wt% were studied using dynamic light scattering (DLS). The effect of MEH-PPV concentrations on the film surface morphology prepared by spin-coating of MEH-PPV/THF solutions was studied using atomic force microscope (AFM). The overlap concentration C* obtained from intrinsic viscosity measurement was around 0.7 wt%. The experimental results revealed that the MEH-PPV particle. sizes remained a fixed value as MEH-PPV concentration was below 0.6 wt% but as MEH-PPV became larger due to aggregation of polymers. At a MEH-PPV concentration lower than 0.6 wt%, the polymer distribution on the surface of film prepared by spin- coating, obtained from AFM observation was not continuous, with a highly rough surface. As MEH-PPV concentration was higher than 0.7 wt%, the surface of the film prepared from spin-coating continuous and less roughness.

並列關鍵字

poly(NIPAM) ； MEH-PPV ； DLS ； AFM