兩性型規則樹枝狀高分子應用於製備多孔性蜂窩狀膜之研究

Honeycomb-like Films Based on Amphiphilic Poly(urea/malonamide) Dendrons

賴郁文(Yu-Wen Lai)

指導教授 ： 鄭如忠

國立臺灣大學/工學院/高分子科學與工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01924

摘要

本研究將兩性型的樹枝狀高分子當作界面活性劑，混摻入四種不同極性的高分子溶液中，再利用高濕度空氣作為驅動力，使具有自主裝能力的兩性型樹枝狀高分子排列在液滴外圍，並防止液滴聚集；未聚集的液滴經過排列之後，形成規則六角形蜂窩狀孔洞結構。
實驗使用的poly (urea/malonamide) 樹枝狀高分子，內部是相對親水、具有強氫鍵的poly (urea/malonamide) 結構；外圍是相對疏水、具有較強凡得瓦力的長烷鏈段，高代數下長烷鏈段較多，氫鍵也較多，形成的兩性高分子親疏水平衡較佳，使我們能夠透過breath figure的製程，得到規則蜂窩狀多孔膜的結構。
本研究選用極性較低的聚苯乙烯、極性中等的聚碳酸酯和聚甲基丙烯酸甲酯以及極性較高的側鏈型聚氨酯四種高分子為基材，與兩性型樹枝狀高分子進行混摻，藉由調控不同的混摻比例和不同的溶質與溶劑比例，來探討不同極性的高分子與樹枝狀高分子混摻後，對孔洞型態的影響。
由SEM觀察，中等極性的高分子與兩性型樹枝狀高分子混摻後，較易形成規則的蜂窩狀孔洞；低極性的高分子則需要在適當的條件下，才能夠形成規則的蜂窩狀孔洞；高極性的高分子則需要再更為嚴苛的環境下，規則蜂窩狀孔洞才有機會形成。而從接觸角的測試中，發現不同的混摻比例對接觸角的影響較不同的溶質與溶劑比例來得大。另一方面，聚碳酸酯和聚甲基丙烯酸甲酯與兩性型樹枝狀高分子混摻後，在較低的混摻比例下，形成的膜能夠自行與玻璃基材分離。

關鍵字

兩性型樹枝狀高分子 ； 混摻 ； 氫鍵 ； 極性

並列摘要

Hydrogen bond-rich amphiphilic dendrons were utilized as surfactants to be respectively blended with four polymers with different polarities. Under highly humid environment, a driving force compels the amphiphilic dendrons to gather at the periphery of water droplets. Owing to the self-assembling ability of dendrons, water droplets won’t gather with each other, and would form hexagonal honeycomb structures. Consequently, honeycomb-like polymeric films could be easily induced by a breath figure process.
A building block, 4-isocyanato-4’(3,3-dimethyl-2,4-dioxo-azetidino) diphenylmethane (IDD), featuring dual-functional groups, has a highly reactive isocyanate functional group, and a selectively reactive azetidine-2,4–dione functional group. Utilizing high reactivity of isocyanate and selective reactivity of azetidine-2,4-dione, higher generation poly(urea/malonamide) dendrons were obtained by the addition reaction with another building block diethyltriamine (DETA). The sequential addition reactions were developed under mild condition without resorting to painstaking protection-deprotection or activation methodology.
Higher generation dendrons exihibited better hydrophilic/ hydrophobic balance owing to their abundance of urea/malonamide linkages and peripheral long alkyl chains. Furthermore, after reacting a 2.5 generation dendron with N-(3-aminopropyl)diethanolamine (APDEA) , this amphiphilic compound (A-[G-2.5]-C18) exhibits strong hydrogen bonding interaction at the focal segment and intense van der Waals force at the peripheral part.
This amphiphilic dendron was then blended with a low-polarity polymer–(polystyrene, PS), medium-polarity polymer –(polycarbonate and poly(methyl methacrylate), PC and PMMA) and a high-polarity polymer–(polyurethane, PU), repcetively. Morphologies of the porous structures would be dependent on hydrophilic/hydrophobic balance and concentrations of amphiphilic dendrons.
The best honeycomb films could be achieved by dendrons respectively blended with PC or PMMA, i.e., medium-polarity polymers, through the investigation of SEM images. With further tuning of the conditions, good quality honeycomb films could be achieved for PS/dendron and PU/dendron systems. Apart from that, different blending ratios would exert much impact on contact angles when compared with other factors such as concentrations. Furthermore, free standing films could be obtained from PC/dendron and PMMA/dendron systems at low blending ratios.

並列關鍵字

Amphiphilic dendron ； Blend ； Hydrogen bonding ； Polarity

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