臺灣博碩士論文加值系統

聚乳酸高分子由於具有良好的生物相容性及生物可降解性，因此被廣泛使用於細胞支架、藥物載體及高分子薄膜上，經由文獻得知聚乳酸高分子多孔微結構的生成主要來自於固化時液/液相分離所造成，因此本研究以建立DL-聚乳酸-溶劑-非溶劑三成分系統之相圖，並藉由改變溫度、溶劑及非溶劑來瞭解其相分離的行為，並且使用Yilmaz提出之理論運算來評估液/液相分離的位置，經由實驗結果可知溫度下降會導致液/液相分離曲線往高分子與溶劑軸移動；當改變溶劑時，若高分子與溶劑間互溶性佳則液/液相分離區域會變小，此效應在溶劑與非溶劑間的互溶性佳時更顯著；當改變非溶劑時，若溶劑與非溶劑有較佳的親和力，則液/液相分離區域變大，且當高分子與非溶劑間幾乎不互溶時會造成更大的液/液相分離區域。理論分析是藉由將實驗系統的作用力參數求出並代入程式中進行運算：可知當 g12＜ g13時，g12 下降則液/液相分離的區域變大；當g23及g13 下降則液/液相分離區域變小，此現象在g12下降時更顯著。實驗上觀察到的液/液相分離現象與理論運算上所得到的結果趨勢吻合，但實驗點與理論所得到的binodal curve 有些誤差，判斷乃是由於作用力參數值估算誤差，及未考慮g12 的濃度相關性所造成。

Due to its superior properties of biocompatibility and biodegradability, polylactide has been widely used in the preparations of cellular scaffolds, drug carriers, and polymer film. Literature reviews indicate that porous structure of polylactide mainly caused by the liquid-liquid demixing of the solidification process. This study constructs the phase diagrams of DL-PLA-Solvent-Non-solvent ternary systems to explore the behavior of phase separation by tuning temperature, solvent and nonsolvent. Theoretical liquid-liquid demixing gap based on model proposed by Yilmaz are also included. Our experimental results show that when temperature decreases, liquid-liquid demixing gap moves toward polymer-solvent axis; when we change solvent, the increase in the miscibility between polymer and solvent will decrease the area of liquid-liquid demixing gap. This effect becomes even more noticeable with better mutual affinities between solvent and nonsolvent. By changing nonsolvent, if the miscibility between solvent and nonsolvent increases, liquid-liquid demixing gap becomes larger. This effect becomes more prominent when polymer and nonsolvent are barely miscible. Theoretical analyses, in which interaction parameters are evaluated by our solubility tests, reveal that when g12 ＜ g13 ， liquid-liquid demixing gap becomes larger with decrement of g12 , and increment of g23 and g13 . The experimental observations in liquid-liquid demixing have the same trends with the results of theoretical prediction; however, the exact values of binodal curves are different. The differences between the experimental and theoretical binodal curves might be caused by the error of the interaction parameters applied and by the neglect of the concentration dependency of g13 .
Key word: Interaction parameters; Flory-Huggins; phase diagram

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