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標題: Syntheses and Characterizations of Polyurethane/Malonamide Dendrimers
Polyurethane/Malonamide Dendrimers的合成及鑑定
作者: 陳衍甫
關鍵字: 聚胺基甲酸酯;polyurethane/malonamide dendrimers;界面活性劑;異氰酸鹽;[2+2]環化反應;surfactant;ketene;isocyanate;azetidine-2;4-dione;dendrimers;[2+2] cycloaddition
出版社: 化學工程學系
Dendrimers are found to have many outstanding properties over their corresponding linear analogues. For instance, they possess lower viscosity, higher solubility, more terminal functional groups, and greater reactivity as compared to the related linear counterparts. These characteristics have been applied in useful applications, and hence have attracted both academic and industrial interests. However, their developments have been hampered by limited synthetic methodologies.
In this study, we have successfully synthesized useful intermediates (TIA and MIA), two mono-isocyanato-azetidine-2, 4-diones based on cycloaddition of 2,4-toluene diisocyanate (2,4-TDI) and 4,4'-methylene-diphenylene-diisocyanate (4,4'-MDI) with ketenes. These two intermediates have been found to be well suited for the rapid syntheses of polyurethane/malonamide dendrimers.
In this study, we demonstrated that the isocyanate group and the azetidine-2, 4-dione group of TIA or MIA have distinctively different reactivity toward hydroxyl and amino-group of amino-alcohol respectively. Addition reactions of hydroxyl groups of alcohol toward isocyanates and ring-opening reactions of azetidine-2, 4-diones by primary aliphatic amines are highly selective and the products are generally formed in high yields. Therefore, sequential and repetitious addition reactions of MIA (or TIA) and amino-alcohol on an initiating alcohol or diols resulted in facile formations of polyurethane/malonamide dendrimers.
Polyurethane/malonamide dendrimers thus synthesized have been found to be surface-active compounds. For instance, Dendrimer DG3 which was synthesized from MIA and N-(3-aminopropyl)diethanolamine lowered the interfacial tension of toluene/water to 15.7 mN/m at 10-5 weight percent.

Dendrimers與線性類似物(linear analogues)的性質做比較,dendrimers具有以下優點(1)低黏度(2)高溶解度(3)許多末端官能基(4)高反應性。且其應用範圍廣泛,這是如今使許多學者及業界正爭相投入研究的領域。但到目前為止仍然只依賴幾種較有效的合成策略。
本研究以TDI和MDI與ketene進行環化反應,所合成之monoisocyanato-azetidine-2,4-dione單體(TIA和MIA)與胺基醇,進行逐步式的交替反應。可以簡單且直接合成出polyurethane/malonamide dendrimers,並且是可精準控制分子結構之合成策略。
經由實驗結果得知,monoisocyanato-azetidine-2,4-dione與胺基醇進行逐步式的交替反應,確實可以輕易的合成出polyurethane /malonamide dendrimers。Isocyanate與醇類的加成反應,以及azetidine-2,4-dione與脂肪族一級胺的開環反應,都是具有高選擇性及高產率的合成方法。因此以一元醇或二元醇為起始,逐步式的與MIA(或TIA)和胺基醇交替進行反應,可以輕易的合成出polyurethane /malonamide dendrimers。
Polyurethane/malonamide dendrimers由界面張力之測定,證明所合成之polyurethane/malonamide dendrimers DG3,在濃度極稀釋的情況下(10-5wt%),可以降低水與甲苯的界面張力至15.7 mN/m。因此有應用於界面活性劑之潛力。
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