Cooperative effects in the transport of small molecules through an amorphous polymer matrix

The transport of small molecules (penetrants) through polymer materials proceeds by a hopping mechanism: A penetrant typically dwells in a cavity of the polymer for a while and then performs a quick jump into an adjacent cavity. In this article we investigate a jump event in detail. Molecular graphics is used to identify if and how the motion of the penetrant is aided by the fluctuations of the polymer matrix. We employ both traditional molecular graphics techniques to show atomic motion and surface rendering methods to display the redistribution of penetrant-accessible volume in the polymer.