Phase Behavior of Aqueous Poly(acrylic acid-g-TEMPO)

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• 作者：Qiang Fu ; Zachary Russell Gray ; Art van der Est ; Robert H. Pelton
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：July 12, 2016
• 年：2016
• 卷：49
• 期：13
• 页码：4935-4939
• 全文大小：325K
• 年卷期：0
• ISSN：1520-5835

文摘

Poly(acrylic acid) with grafted TEMPO moieties, PAA-T, phase separates over the pH range 2–4, whereas at lower and higher pH, the polymer is water-soluble. The pH range of the two-phase region increases linearly with the content of grafted TEMPO moieties. As evidenced by surface tension measurements, the PAA-T molecules have little hydrophobic character. We propose that at low pH PAA-T is an amphoteric polymer that, in addition the anionic carboxyl groups, contains cationic species resulting from the disproportion of TEMPO at low pH. Furthermore, we propose that two-phase regions occur near the isoelectric points of the polymer, suggesting that phase separation is due to electrostatically driven association of polymer molecules.