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標題: 由逐步重覆合成法精準合成聚(胺酯-尿素)中之硬鏈段長度與結構之研究
作者: 郭明杰
Chieh, Kuo Ming
關鍵字: Hard-segment Size
Precise Synthesis

出版社: 化學工程學系
摘要: 一些文獻報告中提到聚(胺酯-尿素)中硬鏈段的長短及分佈會對聚胺酯的熱性質、機械性質有極大的影響,同時也是導致相分離程度的主因。近來更多研究顯示在高分子末端導入多樣的氫鍵官能基會幫助形成強化機械性質的超分子型高分子。在眾多製造熱可逆高分子的方法中,其中之一即為超分子型化合物。自古以來,鮮少有文獻能夠製備出明確結構的硬鏈段單體,本研究已實現並且找出製造此明確分子結構的新化學途徑,同時努力完成一系列新的熱可逆高分子。 文中使用一具備不同活性雙官能基的MDI衍生物當作整個研究的關鍵角色。這個中間體一邊具備高活性的異氰酸基,另一邊為選擇活性的Azetidine-2,4-dione。這可以允許我們實現選擇性基質連續逐步加成到分子上,此一手法類似”Cascade“合成。共三代的Urea-malonic衍生物單體已經製備完成且當成本研究的硬鏈段化合物。這些硬鏈段衍生物被接到PTMEG結構的軟鏈段聚胺酯上,目的是形成線性三區段形式的超分子型高分子。 合成硬鏈段部分,本研究已經能達到控制硬鏈段長度的能力,但隨著硬鏈段代數增加而其純度也跟著降低。利用這些硬鏈段所製備成三區段團聯共聚高分子後,每一世代硬鏈段的熱性質及玻璃轉化溫度會隨著世代增加(長度增加)而有上升的趨勢。在這些高分子的物性量測上,硬鏈段鏈長對於物性有極大的影響。尤其是熱性質、機械性質及相分離程度上皆隨著硬鏈段長度有顯著的提升。最後,在30℃到200℃溫度區間,由於變溫 IR及利用DSC反覆熱處理結果證明硬鏈段部分之氫鍵的形成與瓦解的程序,此為熱可逆性質的存在。
There are a number of studies that have correlated the significant impact of hard segment chain-length with the mechanical performance of polyurethane-urea. In the meantime, the same effect also has been implicated in the phase segregation phenomenon of PU. In more recent studies, introduction of multiple hydrogen-bonding functional groups at the terminals of molecules has been shown to the formation of supra-polymers of enhanced mechanical properties. This supra-molecular synthetic approach was identified to be one of the approaches in making thermal reversible polymers. Since there are few cases in the literature showing the preparation of hard-segment group with well-defined structures, this study has been carried out to synthesize those molecules in an effort to make a series of new thermal reversible PU polymers with possible phase-segregation phenomenon. We have utilized a MDI based derivative with two functional groups of different reactivity as our key building block. This intermediate possesses a highly reactive isocyanate group in one side of the molecule and an azetindine-2,4-dione in the other. This allows us to carry out the sequential step-wise additions of selective substractes to the molecule in manners similar to “Cascade”synthesis. Three generations of urea-malonic derivertives has been prepared as our hard-segment compounds. These derivertives also have been attached to the both ends of PTMEG based soft segment PU prepolymers in formation of linear tri-block type supra-polymers. The capability of controlling the chain-length of hard segments has been achieved in this work. However the purity of hard-segment composition appears to decrease with increasing generation. After PU triblocked polymer were prepared with these hard segments, the results showed that the thermal stabilities and TgH were found to increase with increasing of the chain-length. On measurement of polymer's physical properties, there is also a strong influence of the chain-length of hard segments. Especially thermal properties, mechanical properties and the degree of segregation all are remarkably enhance with increasing chain length. Finally, the measurements from variable temperature IR and DSC between 30℃-200℃ the exsiting of revealed that the thermal reversibility due to the formation and destruction of hydrogen-bondings between the hard-segment chains.
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