PEO-b-P4VP及其錯合物之低臨界有序化現象研究

Lower Critical Ordering Transition of Poly(ethylene oxide)-block-Poly (4-vinylpyridine) and Its Complexes with Dodecylbenzene Sulfonic Acid

李若婷(Ro-Ting Lee)

指導教授 ： 陳信龍

國立清華大學/工學院/化學工程學系/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00345

摘要

我們利用小角度X光散射實驗解析各種分子量與組成的嵌段共聚物poly(ethylene oxide)-block-poly (4-vinylpyridine) (PEO-b-P4VP)以及參混界面活性劑dodecylbenzene sulfonic acid(DBSA)的相轉換行為。結果發現，PEO-b-P4VP共聚物可以呈現一種極不尋常的「低臨界有序化」(lower critical orderingtransition，LCOT)行為，即在低溫時PEO與P4VP鏈段互容，但當加熱至一臨界溫度時，兩鏈段發生微相分離，呈現一種「無序到有序態的轉化」(disorder-to-order transition，DOT)。奈米結構的形態乃是受控於兩鏈段的分離強度(χN)和體積分率，在多組不同分子量的PEO-b-P4VP中，我們發現兩相中較不對稱比例和較小的分子量，會導致無序到有序態之轉化溫度的上升。除了以實驗建構相圖之外，我們亦將運用文獻上的理論模型定量計算PEO-b-PVP系統的相圖，藉由與實驗相圖的擬和，揭露共聚物呈現LCOT相行為的機制與驅動力。根據P4VP以及其異構物P2VP，一個給定的組成和分子量，PEO-b-P4VP共聚物的無序到有序態之轉化溫度低於PEO-b-P2VP，這是由於P4VP和P2VP的溶解度參數之間的差距。另外，當PEO-b-P4VP(DBSA)中的DBSA增量時，會導致無序到有序態之轉化溫度上升，由於產生不對稱的組成和兩相之間的χ參數的改變。

關鍵字

小角度X光散射 ； 低臨界有序化現象

並列摘要

We have investigated the phase transition behavior of poly(ethylene oxide)-block-poly(4-vinyl pyridine) (PEO-b-P4VP) and its complexes with dodecylbenzenesulfonic acid (DBSA). PEO-b-P4VP was found to exhibite an unusual lower critical ordering transition (LCOT), where the diblock, which was in the disordered state at lower temperature, underwent microphase separation upon heating. The disorder-order transition temperature (TDOT) of PEO-b-P4VP was in general significantly lower than that of PEO-b-P2VP under a given composition and molecular weight. This was attributed to the larger solubility parameter of P4VP than that of P2VP. The complexation of P4VP block with DBSA drastically increased the TDOT due to the shift of the copolymer composition to more asymmetric value and the modification of the χ parameter between the two blocks. The supramolecular comb-coil diblock copolymers thus formed exhibited the structure-within-structure morphology above TDOT.

並列關鍵字

SAXS ； LCOT

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