Roorda W
ALZA Corporation, Palo Alto, CA 94303.
J Biomater Sci Polym Ed. 1994;5(5):383-95.
In the first part of this article calorimetric studies on poly (hydroxy ethyl methacrylate) (PHEMA) are presented. In the past the irregular melting curves in this type of experiment have been interpreted as evidence for the existence of different types of water in these gels. The studies presented here demonstrate that the occurrence of a glass transition in the freezing hydrogels may be responsible for this irregular melting behavior, and that this behavior is not (necessarily) an indication for the existence of different types of water. In the second part results are shown of measurements of the mobility of water in hydrogels, made by relaxation NMR. These results indicate that very rapid interchange occurs between the water molecules, and they support the conclusion that the calorimetric data mentioned above are not indicative for the existence of different classes of water in hydrogels. These results are compared with data from other fields of science, especially from fundamental freeze drying studies, which support the alternative interpretation of the calorimetric measurements.
本文第一部分介绍了对聚甲基丙烯酸羟乙酯（PHEMA）的量热研究。过去，这类实验中不规则的熔化曲线被解释为这些凝胶中存在不同类型水的证据。此处呈现的研究表明，冷冻水凝胶中玻璃化转变的出现可能是这种不规则熔化行为的原因，并且这种行为并不（一定）表明存在不同类型的水。第二部分展示了通过弛豫核磁共振测量水凝胶中水的迁移率的结果。这些结果表明水分子之间发生了非常快速的交换，并且支持了上述量热数据并不表明水凝胶中存在不同类别水的结论。将这些结果与其他科学领域的数据进行了比较，特别是来自基础冷冻干燥研究的数据，这些数据支持了对量热测量的另一种解释。
