利用超臨界二氧化碳製備溫度/PH敏感型核殼複合材料

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題名:	利用超臨界二氧化碳製備溫度/PH敏感型核殼複合材料 Synthesis of Thermo/Ph Sensitive Core-Shell Composites by Using Supercritical Carbon Dioxide
作者:	曾梨子
貢獻者:	化學工程與材料工程學系
關鍵詞:	超臨界聚合反應核殼複合物溫度酸鹼雙敏感型材料 supercritical polymerization core-shell composite thermo-pH sensitive materials
日期:	2014-08
上傳時間:	2014-10-23 10:05:24 (UTC+8)
摘要:	環境敏感型高分子材料最早是在生物體內發現的，因為生物體內的環境複雜，生物高分子必須因應刺激而產生形態與結構的變化，引發適當的生理反應機制以維持生物體內正常運作，隨著科技進步，對於智慧型高分子作用機制的認知增加，人工合成的環境敏感型高分子亦趨發展，其中以溫度敏感型(thermo-sensitive)與酸鹼敏感型(pH-sensitive) 高分子相關研究最多，且應用最為多元。當高分子溶液低於某一溫度可形成均勻溶液為低臨界溶液溫度(LCST)敏感型，反之則為高臨界溶液溫度(UCST) )敏感型，而酸鹼敏感型高分子溶液的 pH 低於其 pKa時，解離度低，分子鏈呈收縮狀態；當 pH高於 pKa時，則發生去質子化，高分子鏈帶負電荷產生靜電排斥，延展在水溶液當中，因此 pH值敏感性高分子在水中能產生膨潤(swelling)與收縮(shrinking)改變。有鑑於此，本計畫也針對合成溫度和酸鹼雙敏感型核殼複合物(core-shell composite)的製備方法做深入之研究，此環境敏感型複合材料應用領域廣泛，包括環境感測、生醫工程純化技術以及藥物釋放調控等。為了避免溶劑的殘留及綠色環境的策略，將實驗室已建立的反應設備，以超臨界二氧化碳(SCCO2)為溶媒，進行合成製備溫度和酸鹼雙敏感型的複合材料，第一年的研究，以偶氮二異丁腈(AIBN)當作起始劑，及 N,N'-亞甲基雙丙烯醯胺(Bis)為交聯劑，單體 N- 異丙基丙烯醯胺 (NIPAM) 為基礎材料，其中加入少量親水性單體甲基丙烯酸 (Methacrylic acid, MAA)，經由調整組成材料的比例以達到目標最低臨界溶液溫度 LCST，進行共聚合反應生成溫度敏感型高分子 P(NIPAM-co-MAA)，酸鹼敏感性材料為聚二甲基矽氧烷接枝聚丙烯酸(PDMS-g-PAA)，其兩性分子可同時做為穩定劑用途，使交聯共聚合高分子形成微胞核殼 P(NIPAM-co-MAA)/PDMS-g-PAA複合物。並以傅立葉轉換紅外線光譜儀(FTIR)確認產物結構分析、掃描式電子顯微鏡(SEM)觀察複合物表面形貌、穿透式電子顯微鏡(TEM)觀察複合物 core-shell型態、以紫外光-可見光譜儀(UV-Vis spectrometer)測量體積相變化，分析溫度敏感性質、以膨潤度(swelling ratio)測量，分析 pH 值敏感性質、及熱重分析儀 (TGA)分析產物熱裂解溫度(Td)性質。本研究第二年，進一步尋求實驗參數反應物用量對複合物性質的影響，預期可調整反應物比例使產物的 LCST 溫度控制至人體正常體溫或發炎狀況範圍之間，反應溫度選用 70oC 為起始劑 AIBN裂解溫度，改變 SCCO2的其他操作參數如反應壓力、時間等。並針對其物理化學性、環境應答特性進行研究及探討，並進行體外藥物控制釋放實驗，測試做為藥物包覆載體的可能性，評估實際應用的可行性並作為相關研究的參考。 Environmentally sensitive polymers were first found in biological vivo. To maintain the normal operation of a living body, the morphology and structure of polymers change in response to the physiological stimulations induced in biological vivo. With awareness of technological progress, synthetic of intelligent polymers were investigated. And the developments of thermo-sensitive and pH-sensitive polymers draw much attention. When the polymer solution shows homogeneously below a critical solution temperature (LCST) or upper a critical solution (UCST) is called thermo-sensitive polymer. And pH-sensitive polymer can produce swelling or shrinking changes in solution. When the pH of the polymer solution below is its pKa, contraction is appeared in molecular chain due to low degree of dissociation; otherwise, the deprotonated polymer chain extends in aqueous solution due to electrostatic repulsion of negative charge. In this project, synthesis of thermo-pH sensitive core-shell composite by using supercritical fluid technology is studied. These environmentally sensitive composites are wide range of applications, including environmental sensing, biomedical purification and drug release control. The copolymerization reaction of environmentally sensitive polymer has traditionally been synthesized by using organic solvents. For the sake of avoided solvent residue and environmental protection, those traditional methods can be replaced by other green processes. Our laboratory has established a response equipment by using supercritical carbon dioxide (SCCO2) as green solvent. In the first year of study, with 2,2-Azobis(isobutyronitrile) (AIBN) as initiator and N,N'-methylenebisacrylamide (Bis) as crosslinker, monomer N-isopropylacrylamide (NIPAM) as based material was copolymerized with the hydrophilic monomer (Methacrylic acid, MAA) to form temperature-sensitive core, P (NIPAM-co-MAA). Poly dimethyl siloxane grafted polyacrylic acid (PDMS-g-PAA) serves as pH-sensitive shell. By the way, PDMS-g-PAA features vitally as surfactant in the process, which stabilizes the polymer particles sterically in the dispersion polymerization, and as the contributor of additional functionality to the final product, (NIPAM-co-MAA) / PDMS-g-PAA core-shell composite. Therefore, the sensitivity of pH and temperature can be tuned individually. The structure of the result product can be confirmed by Fourier transform infrared spectroscopy (FTIR), SEM images will show the size and morphology of products, transmission electron microscopy (TEM) observation composite core-shell appearance, UV-Vis spectrometer measured volume changes , analyze the temperature-sensitive nature, swelling ratio measurement analyze the pH-sensitive phenomena, and the degrading temperature of polymer is studied by TGA. In the second year, We will also investigate the effects of reaction factors. The operation temperature is set at 70oC, the decomposition temperature of the initiator AIBN. The influence of the impregnation of hydrophilic monomers, cross-linker concentration, reaction time, and conducting pressure are investigated. The results for optimal operation conditions are expected that are valuable to future industrial applications. Furthermore, the environmental response characteristics were studied and in vitro release of drug was examined, testing as drugs coated carrier possibilities for evaluating the feasibility of practical applications.
顯示於類別:	[Department of Chemical & Materials Engineering] project

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