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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;硬鏈段;poly(urethane-urea);Precise Synthesis;Cascade;聚;胺酯-尿素;精準合成
出版社: 化學工程學系
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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