Controlled Permeability of Polyelectrolyte Capsules via Defined Annealing

The influence of thermal treatment on the permeability of polyelectrolyte multilayer capsules is studied via confocal fluorescence microscopy of individual microcapsules. For the specific most frequently used example, capsules made of poly(styrenesulfonic acid) and poly(allylamine hydrochloride), the penetration of fluorescein is shown to be reduced by 3 orders of magnitude on heating at 80 °C. The data show that holes formed during preparation may be annealed in a predictable way.