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標題: | 左旋聚乳酸-聚乙二醇與左旋聚乳酸-乙二醇團聯共聚合物對聚乳酸結晶行為以及結晶型態的影響 Effect of PEG-PLLA and EG-PLLA triblock copolymer on the crystallization behavior and morphology of PLLA |
作者: | Kuan-Lun Feng 馮冠倫 |
指導教授: | 廖文彬(Wen-Bin Liau) |
關鍵字: | 聚乳酸,聚乙二醇,結晶動力學,形態學, PLLA,PEG,crystallization kinetics,morphology, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 過往已有諸多文獻討論聚乙二醇與左旋聚乳酸的混摻系統以及共聚合物,聚乙二醇的加入會提升左旋聚乳酸的結晶速度,並改變結晶型貌造成環狀結構的形成。本研究以開環聚合法合成出左旋聚乳酸-乙二醇團聯共聚合物(EG-PLLA triblock copolymer)以及左旋聚乳酸-聚乙二醇團聯共聚合物(PEG-PLLA triblock copolymer),並將兩種共聚合物分別與左旋聚乳酸(PLLA)混摻。我們分別利用熱微差掃描分析儀(DSC)與偏光顯微鏡(POM),以過往研究為基礎討論團聯共聚合物中間鏈段長短不同對左旋聚乳酸結晶性質及結晶型貌的影響。 透過 DSC 的觀察可以發現 PEG 鏈段較長有較多的分子鏈組態會提升 PLLA的鏈運動能力;EG 鏈段較短,對分子鏈組態影響不大,對 PLLA 鏈運動能力影響較小。兩種共聚合物皆會使熔融熵上升而造成平衡熔點下降,其中 PEG 鏈段對於系統熔融態熵的影響較 EG 鏈段大。添加兩種共聚合物皆會使 PLLA的球晶成長速度上升,PEG 鏈段是藉由鏈運動能力上升及表面自由能下降影響,EG 鏈段則是藉由表面自由能下降影響,但兩種共聚合物造成表面自由能下降的原因不同。EG 鏈段造成影響的原因是來自於摺疊時的分子鏈摺疊方式與構型受到影響,而 PEG 鏈段造成表面自由能下降的原因除了來自於 PEG 鏈段造成摺疊方式與構型影響以外,還有 PEG 鏈段與 PLLA 之間的吸引力影響高分子鏈摺疊。 兩種共聚合物的混摻系統皆可觀察到環狀結構。我們認為這是由於加入共聚合物後改變了高分子鏈的摺疊,使得表面自由能下降,因而造成晶片扭轉。我們也發現加入含有 PEG 鏈段的系統環狀間距較加入含有 EG 鏈段的系統小,這是因為吸引力對於摺疊的影響大於鏈構型改變對摺疊的影響。 Previous studies have shown that the addition of polyethylene glycol (PEG) will increase the crystallization growth rate of Poly L-lactic acid(PLLA) and change the crystalline morphology to form a ring banded structure. In our study, PEG-PLLA triblock copolymer and EG-PLLA triblock copolymer were synthesized by the ring-opening polymerization method. Two copolymers are blended with poly L-lactic acid separately. We used thermal Differential Scanning Calorimetry (DSC) and polarized optical microscope (POM) to discuss the influence of the length of the middle segment of the triblock copolymer on the crystalline properties and morphology of PLLA based on previous research. Through the observation of DSC, it can be found that PEG chain segments will improve the chain mobility by increasing molecular chain configurations; EG chain segments have scarcely effect on the molecular chain configuration which causes less influence on the chain mobility. Both copolymers will increase the melting entropy and cause decreasing in the equilibrium melting point, but the PEG segment has a greater influence on the melting entropy than the EG segment. The addition of two copolymers will increase the growth rate of the PLLA spherulites growth rate. The PEG segment is affected by the increase in chain motility and the decrease in surface free energy, while the EG segment is affected by the decrease in surface free energy. Two copolymers cause different reasons for the decrease in surface free energy. The reason for the influence of the EG segment is that the folding method and folding configuration. For the PEG triblock system. However, the reason for the decrease in surface free energy caused by the PEG segment is not only from the folded method and folded configuration of the PEG segment but also the attractive force between the PEG segment and PLLA affects the folding of the polymer chain. The ring banded structure can be observed in both blended systems of the two copolymers. We believe that this is because the addition of the copolymer changed the folding of the polymer chain, causing the surface free energy to decrease, which caused lamellae twisted. We also found that the periodic distance of the PEG blending system is smaller than that of the EG blending system. This is because the influence of attractive force on folding is greater than that of chain configuration changes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/71383 |
DOI: | 10.6342/NTU202004367 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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