| Abstract
| - By using a combination of atomic force and confocal microscopy, we explore the effect of pH and salton the stiffness of polyelectrolyte microcapsules with shells composed of strong polyanions and weakpolycations. The stiffness of the capsules was found to be largest in water. It decreases slightly with addedsalt and gets much smaller both in acidic and in alkaline solutions. The moderate softening of the capsulesin electrolyte solutions indicates that even high salt concentration does not significantly dissociatepolyelectrolytes in the multilayer. The dramatic softening of the capsules at high pH probably reflects adecrease in the charge density of a polycation, which leads to a reduction in the number of ionic cross-links.In contrast, low stiffness of the capsules in acidic solutions seems to be connected mostly with the enhancedpermeability of the multilayer shell.
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