Does water swell the ordered domains in polyelectrolyte/clay multilayers

X-ray diffraction has been used to study the sorption of water by multilayer films containing ordered stacksof alternating layersof an organic polyelectrolyte and individual plateletsof a smectite. The position and shape of the 001 reflections due to the ordered polyelectrolyte/platelet stacks were essentially the same when in air at low relative humidity (23 25% RH) and under water. These data indicate that swelling occurs exclusively in X-ray amorphous regions within the film, and that the ordered polyelectrolyte/clay domains themselves are not ‘swellable’ by water.