Solubility of water in polyimides: Quartz crystal microbalance measurements

The solubility of water vapor in four different polyimides at 100% relative humidity and 22°C was measured by means of a quartz crystal microbalance system. The results confirm earlier conclusions that diffusion in these polymers is Fickian, and are sufficiently precise that the order of solubilities is unambiguous. The differences between the values are interpreted in terms of morphological variations rather than variations in chemical affinity for water. Diffusion coefficients are also reported. Copyright © 1991 John Wiley & Sons, Inc.