PNIPAAm與PEVAL全互穿網狀結構之高分子水膠薄膜製備與性質研究

Synthesis and Characterization of Thermo-sensitive Hydrogel Membranes with Interpenetrating Networks Structure of Poly(N-isopropylacrylamide) and Poly(ethylene-co-vinyl alcohol)

胡智遠(Jiang-Yuan Hu)

指導教授 ： 孫一明

元智大學/工程學院/化學工程與材料科學學系/碩士(2002年)

摘要

摘 要
本研究摻合不同比例的聚-氮異丙基丙烯醯胺（N-isopropylacrylamide, NIPAAm）與聚乙烯共乙烯醇（poly(ethylene-co-vinyl alcohol), PEVAL），利用自由基聚合並添加交聯劑MBAAm交聯PNIPAAm，同時進行胺酯基（urethane）交聯反應使PEVAL交聯，以製備全互穿高分子網狀結構（fully-interpenetrating polymer networks）的水凝膠（hydrogels）薄膜。並對膜材之成份、結構特性、熱性質、機械性質及膨潤特性進行一系列的分析。
由紅外光光譜分析（infrared spectroscopy）、元素分析，可確認兩組之交聯反應的進行。而由SEM（scanning electron microscopy）照片觀察，可得知膜材之微結構隨著EVAL含量的增加，由孔洞膜材逐漸轉變為緻密型膜材的過程。
由DSC（differential scanning calorimetry）分析，所有膜材僅可見一明顯的Tg，此可證明此膜材兩種主要成份在非定形區（amorphous phase）均勻混合；同時，隨著PEVAL含量增加，膜材的Tg點逐漸降低，此外，由結晶熱吸熱峰可知，除了非定形區外，膜材之PEVAL部份會單獨形成結晶區塊，且整體結晶熱會隨著PEVAL的含量增加而上升。利用TGA（thermal gravimetric analysis）分析觀察得知，當添加PEVAL，網狀結構之PNIPAAm之裂解溫度將由360 oC降至250 oC。
由拉力試驗機進行水膠之機械性質測試，與預期結果相同，當PEVAL於水膠中的含量增加，其揚氏模數（Young’s modulus）、抗張強度（tensile strength）及伸長量（elongation）均有上升的趨勢。此可由N60E膜材之機械性質均優於N70E膜材證明。
純PNIPAAm網狀結構的平衡膨潤比(swelling ratio)約為10左右，但隨著PEVAL含量增加，PNIPAAm的膨潤性質將大幅度的減少，當PEVAL含量大於40%時，膨潤比僅接近1，幾乎已完全失去了膨潤特性。並由動態膨潤實驗發現，膜材之膨潤速率較收縮速率為快。再由DSC熱掃瞄及平衡膨潤實驗，可驗證水膠薄膜仍具有最低臨界溫度（lower critical solution temperature）的特性。其最低臨界溶解溫度（LCST點）並不會隨著PEVAL的含量改變而有明顯變化，LCST約在26 oC左右。

關鍵字

聚-氮異丙基丙烯醯胺 ； 聚乙烯共乙烯醇 ； 全互穿高分子網狀結構 ； 熱敏感性 ； 水凝膠 ； 最低臨界溫度

並列摘要

Abstract
The gel membranes of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene-co-vinyl-alcohol) (PEVAL) with fully-interpenetrating polymer networks structure were prepared and characterized. The chemical structure of the gels could be confirmed by the infrared spectroscopy and element analysis.
The morphology of the membranes became less porous when more PEVAL was added as the samples were freeze-dried and then observed by SEM. The differential scanning calorimetric, DSC, analysis showed there was only one glass transition temperature, Tg, in all of the xerogel membranes. It indicated that the amorphous portion of the gels was homogeneously blended by PNIPAAm and PEVAL. In addition, the more PEVAL was added, the lower glass transition temperature was obtained. There was also a crystalline region of PEVAL in the IPN gels. Thermal gravimetric analysis showed that the thermal decomposition temperature was shifted to 250 oC from the original thermal decomposition temperature of pure PNIPAAm, 360 oC, by adding PEVAL.
As expected, the mechanical properties were significantly improved when PEVAL was added. The tensile strength, elongation and Young’s modulus of the N60E hydrogel membrane were better than N70E hydrogel membrane because the crystalline region of PEVAL could enhance the mechanical properties of hydrogels.
The more PEVAL was added, the less swelling ratio of the membranes was. The swelling ratio of pure PNIPAAm membranes was 10 but it dropped to 1 if PEVAL content was more than 40%. When PEVAL was added, the LCST of the gels didn’t have much change but the extent of the thermal-responsive properties were reduced.

並列關鍵字

poly(N-isopropylacrylamide) ； PNIPAAm ； poly(ethylene-co-vinyl alcohol) ； PEVAL ； fully interpenetrating polymer network structure ； fully-IPN ； thermal sensitive ； hydrogel ； lower critical solution temperature ； LCST

參考文獻

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