Cross-regulation techniques

The all-dry box procedures resulted in another interesting visual effect. By controlling the solvent removal step that is, how long a vacuum was applied to the polymerization vessel, the location of the polyacetylene within the membrane structure could be regulated. For example, sandwich structures could be created by immediately applying a vacuum to a membrane sample wet with catalyst solution. This technique caused the solution to move into the center of the membrane s cross section thus polyacetylene formed only in the center of the cross section as well. The presence of polyacetylene, then, was hidden by the membrane s surface. Consequently, the surface of the membrane appeared almost white when dry (opaque) but instantly turned very dark when wet with solvent (transparent - polyacetylene then could be seen). Upon drying, the membrane again turned white. The phenomenon could be observed countless times with the same sample. 

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