( in Potsdam have now found out that the...)Microcapsules like it hot and salty

If the temperature is only slightly raised the hollow spheres swell up or shrink and at the same time the wall becomes thinner or thicker. This depends on the composition and the electrical charge of the polymer shell:

• If it shrinks, it is possible to encapsulate very small molecules. With the powerful supply of energy from raising the temperature, the bonds between the polymer molecules with opposite charges are loosened and as a result, the capsule wall becomes softer. The material of the shell can therefore flow closer together; the wall becomes thicker and denser. The molecules can no longer move through it and are enclosed inside.
• If the hollow spheres shrink, the polymer walls also soften when heated. However, there are so many equivalent charges in the capsule wall that they repel each other. The whole structure expands considerably, the diameter increases and the wall becomes thinner. The result is significantly higher permeability compared to the original capsules at room temperature.
• If salt is now added to the capsule solution, the electrical charges are neutralized and the capsules shrink again, the wall thickening as described in the first example above. "By combining simple materials available in any kitchen, we can vary the properties of the wall of the microtransport system in any way we wish," said Karen Kohler, a scientist working on this project at the Max Planck Institute of Colloids and Interfaces in Potsdam. The scope for change in capsules with an original diameter of 4.5 micrometers varies from 1.5 to 20 micrometres (see fig.).

However, it is not just in the laboratory that the size of the capsule can be adjusted precisely. The scientists also have a theoretical understanding of the processes in the caps
'"/>

Source:Max-Planck-Gesellschaft