Six Red Balloons Deliver Surprises and Structure–Property Relationships in Gas Permeability

The movement of gases through a polymer membrane is exemplified by the deflation of common latex balloons. This whimsical example provides a demonstration of the important interplay between kinetics and thermodynamics in determining the course of a process. Six balloons are filled with differing gases, and without prior knowledge, their behavior is difficult to predict. However, a discussion of partial pressures and well-established properties of gas diffusion through polymer films qualitatively explains the behavior, providing a clear example of a structure–property relationship.