Structure of Water Sorbed into Poly(MEA-co-HEMA) Films As Examined by ATR-IR Spectroscopy
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- 作者：Makoto Ide ; Takayuki Mori ; Ken Ichikawa ; Hiromi Kitano ; Masaru Tanaka ; Akira Mochizuki ; Hiroaki Oshiyama ; and Wataru Mizuno
- 刊名：Langmuir
- 出版年：2003
- 出版时间：January 21, 2003
- 年：2003
- 卷：19
- 期：2
- 页码：429 - 435
- 全文大小：112K
- 年卷期：v.19,no.2(January 21, 2003)
- ISSN：1520-5827
文摘
The structure of water sorbed into poly(2-methoxyethyl acrylate) (PMEA), poly(2-hydroxyethylmethacrylate) (PHEMA), and their copolymers (p(MEA/HEMA)) was investigated by attenuated totalreflection infrared (ATR-IR) spectroscopy. The extinction coefficient of the OH stretching band of sorbedwater (
OH) was calculated from the band area obtained by IR measurement and the amount of sorbedwater obtained by thermogravimetric analysis. When the polymers contacted with water vapor (relativehumidity = ~55%), the OH values were quite similar in all polymers. On the other hand, when the polymerscontacted with liquid water, the OH values were drastically changed by the content of 2-methoxyethylacrylate (MEA). When the MEA content of the polymers was low (<60 mol %), the OH value of the watersorbed into polymers in contact with liquid water was equal to that in contact with water vapor. In thehigher MEA content (70-100 mol %), on the other hand, the OH values of the water sorbed into polymersin contact with liquid water were 5-8 times larger than that in contact with water vapor. These resultsseemed to indicate that the interaction between the primary hydration water around the MEA-containingpolymer chain and water molecules surrounding the primarily hydrating water is very weak. Such waterwith a large OH value seemed to correspond to "cold-crystallizable" water, which has been observed byDSC as anomalous water other than intermediate and nonfreezable waters. Taking both the experimentalresults obtained in this work and those thermodynamically obtained previously into consideration, it wasstrongly suggested that the cold crystallization of water is generated by caging water molecules in a smallspace by the polymer chains with a small hydration region. The correlation between the OH value andthe blood compatibility of the copolymer was also discussed.
OH) was calculated from the band area obtained by IR measurement and the amount of sorbedwater obtained by thermogravimetric analysis. When the polymers contacted with water vapor (relativehumidity = ~55%), the OH values were quite similar in all polymers. On the other hand, when the polymerscontacted with liquid water, the OH values were drastically changed by the content of 2-methoxyethylacrylate (MEA). When the MEA content of the polymers was low (<60 mol %), the OH value of the watersorbed into polymers in contact with liquid water was equal to that in contact with water vapor. In thehigher MEA content (70-100 mol %), on the other hand, the OH values of the water sorbed into polymersin contact with liquid water were 5-8 times larger than that in contact with water vapor. These resultsseemed to indicate that the interaction between the primary hydration water around the MEA-containingpolymer chain and water molecules surrounding the primarily hydrating water is very weak. Such waterwith a large OH value seemed to correspond to "cold-crystallizable" water, which has been observed byDSC as anomalous water other than intermediate and nonfreezable waters. Taking both the experimentalresults obtained in this work and those thermodynamically obtained previously into consideration, it wasstrongly suggested that the cold crystallization of water is generated by caging water molecules in a smallspace by the polymer chains with a small hydration region. The correlation between the OH value andthe blood compatibility of the copolymer was also discussed.