臺灣博碩士論文加值系統

本研究使用聚乙二醇單甲醚和左旋-丙交酯以開環聚合合成三種不同分子量的聚乙二醇單甲醚-聚乳酸(mPEG-PLLA)雙團聯共聚物，並以凝膠層析滲透儀(GPC)分析其分子量。
利用共沉澱法將共聚物和粒徑為15-20 nm的四氧化三鐵奈米粒子於水溶液中共組裝形成微胞，使用螢光光譜儀測量臨界微胞濃度，觀察在不同奈米粒子濃度和不同疏水鏈段聚合度時，其臨界微胞濃度、微胞化自由能的變化。探討(1)在不同奈米粒子濃度下疏水鏈段聚合度和臨界微胞濃度冪次關係中的指數(a0)。(2)在不同疏水鏈段聚合度下臨界微胞濃度的自然對數和奈米粒子濃度冪次關係的指數(n0)；以動態光散射儀測量其微胞平均粒徑，觀察其微胞粒徑在不同奈米粒子濃度、不同疏水鏈段聚合度之變化。探討(1)在不同奈米粒子濃度下微胞粒徑和疏水鏈段聚合度冪次關係中的指數(a)。(2)在不同疏水鏈段聚合度下微胞粒徑和奈米粒子濃度冪次關係中的指數(n)；以熱重分析儀分析(TGA)測量微胞中奈米粒子的含量，探討奈米粒子的被包覆率對奈米粒子濃度和疏水鏈段聚合度的關係。並計算奈米粒子於水溶液和微胞核中的平衡常數和分配自由能。
實驗結果發現臨界微胞濃度隨著奈米粒子濃度增加或疏水鏈段聚合度增加而下降，微胞化自由能(負值)的絕對值隨著奈米粒子濃度增加或疏水鏈段聚合度增加而上升。其臨界微胞濃度的自然對數和奈米粒子濃度冪次關係的指數(n0)隨著疏水鏈段長度增加而下降。平均微胞粒徑隨著奈米粒子濃度增加和疏水鏈段長度增加而上升。其微胞粒徑和奈米粒子濃度冪次關係中的指數(n)隨著疏水鏈段長度上升而下降。四氧化三鐵奈米粒子之包覆率隨著奈米粒子濃度增加而下降，隨著疏水鏈段長度增加而上升。奈米粒子於水溶液和微胞核中的平衡常數(K)隨著疏水鏈段長度增加而上升，奈米粒子濃度上升而下降。分配自由能(負值)的絕對值隨著疏水鏈段長度增加而上升；隨著奈米粒子濃度增加而下降。實驗發現當四氧化三鐵奈米粒子濃度愈高時，其微胞化自由能(負值)的絕對值愈高，而奈米粒子的分配自由能(負值)的絕對值愈低，表示隨著奈米粒子濃度增加共聚物自組裝的推動力愈大，而奈米粒子自組裝的推動力卻愈小，奈米粒子濃度對於兩種自由能的影響相反。

This work is to synthesize methoxypoly(ethylene glycol)-poly(L-lactide) (mPEG-PLLA) diclock copolymers with three different lengths of hydrophobic (PLLA) segments by using ring-opening polymerization, and we used gel permeation chromatography (GPC) to determine the molecular weight of mPEG-PLLA diblock copolymer.
mPEG-PLLA diblock copolymers and iron (Ⅱ, Ⅲ) oxide nanoparticles with 15-20 nm average particle size are co-assembled in deionized water by using co-precipitation method. Then we determined the critical micelle concentration (CMC) of diblock copolymers solution by using fluorescent probe with various concentrations of iron oxide nanoparticles and various degrees of polymerization (DP) of hydrophobic (PLLA) segments. And we discussed (1) the power-law exponents (a0) for the CMC versus the DP of hydrophobic segments of diblock copolymers at different concentrations of iron oxide nanoparticles, and (2) The power-law exponents (n0) for natural logarithm of CMC versus the concentrations of iron oxide nanoparticles at different DP of hydrophobic segments.
Then we measured the average particle size of mPEG-PLLA diblock copolymer micelles in aqueous solutions by using dynamic light scattering (DLS) with various concentrations of iron oxide nanoparticles and various DP of hydrophobic segments. And we discussed (1) the power-law exponents (a) for the average particle size of micelle versus the DP of hydrophobic segments at different concentrations of iron (Ⅱ, Ⅲ) oxide nanoparticles. (2) The power-law exponents (n) for the average particle size of micelles versus the concentrations of iron oxide nanoparticles at different DP of hydrophobic segments.
Last we measured the content of iron oxide nanoparticles in diblock copolymer micelles with various concentrations of iron oxide nanoparticles and various DP of hydrophobic segments by using thermogravimetric analysis (TGA). And we calculated the encapsulation efficiency, the equilibrium constant between aqueous solutions and micelles, and the Gibbs free energy of partition at different concentrations of iron (Ⅱ, Ⅲ) oxide nanoparticles and different DP of hydrophobic segments.
Experimental results show that CMC decreases with increasing concentrations of iron oxide nanoparticles and DP of hydrophobic segments. Average particle size of diblock copolymer micelles increases as concentrations of iron oxide nanoparticles and DP of hydrophobic segments increases. And the power-law exponents (n0) for natural logarithm of CMC versus the concentrations of iron oxide nanoparticles and the power-law exponents (n) for the average particle size of micelles versus the concentrations of iron oxide nanoparticles decrease with increasing DP of hydrophobic segments. The encapsulation efficiency of iron oxide nanoparticles and the equilibrium constant increase with increasing DP of hydrophobic segment but decreases with increasing concentrations of iron oxide nanoparticles. The absolute value of Gibbs free energy of partition (negative value) increases with concentrations of iron oxide nanoparticles but decreases with increasing DP of hydrophobic segments. From the results we find when the concentrations of iron oxide nanoparticles increases the absolute value of Gibbs free energy of micellization also increases, whereas the Gibbs free energy of partition decreases. It means the concentrations of iron oxide nanoparticles has an opposite effect on copolymer assembly and iron oxide nanoparticles assembly.
 

一、前言

二、實驗方法
2.1 合成mPEG-PLLA雙團聯共聚物
2.2 凝膠滲透層析儀分析
2.3 測量水溶液中臨界微胞濃度
2.3.1配製待測臨界微胞濃度之共聚物溶液
2.3.2螢光光譜測量臨界微胞濃度
2.4 測量水溶液中微胞粒徑
2.4.1配製待測微胞粒徑之共聚物溶液
2.4.2動態光散射測量微胞粒徑
2.5 測量微胞中奈米粒子含量
2.5.1待測樣品製備
2.5.2熱重量分析儀測量

三、結果與討論
3.1 mPEG-PLLA雙團聯共聚物之聚合與組成分析
3.2 mPEG-PLLA雙團聯共聚物之臨界微胞濃度
3.2.1臨界微胞濃度之測量
3.2.2 四氧化三鐵奈米粒子濃度對臨界微胞濃度之影響
3.2.3共聚物疏水鏈段聚合度對臨界微胞濃度之影響
3.2.4 臨界微胞濃度的自然對數和Fe3O4奈米粒子濃度之關係
3.2.5 臨界微胞濃度與疏水鏈段聚合度之關係
3.2.6微胞化自由能
3.3 mPEG-PLLA雙團聯共聚物之微胞粒徑
3.3.1四氧化三鐵奈米粒子濃度對微胞粒徑之影響
3.3.2微胞半徑比值對四氧化三鐵奈米粒子濃度之關係
3.3.3共聚物之微胞粒徑和疏水鏈段聚合度之關係
3.4四氧化三鐵奈米粒子在共聚物微胞中的組裝
3.4.1 四氧化三鐵奈米粒子在共聚物微胞中之含量
3.4.2四氧化三鐵奈米粒子於共聚物微胞中的包覆率
3.4.3四氧化三鐵奈米粒子在水溶液和共聚物微胞中之分配自由能

四、結論

五、參考文獻

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