Self-Organization by Polymers

09.01.2008

Polymers have become indispensable in our everyday life. They are incorporated
into almost every technical material to modify its properties. Polymers are
synthetic chemical compounds consisting of very long and/or highly branched molecular chains. Such macro molecules can influence the growth of crystals:
When mixing aqueous solutions of the salts needed for crystallizing barium
sulfate, the ions initially combine to form nanocrystals which in turn combine to
form tiny, almost amorphous platelets. However, if the mixing is done in the presence of diluted polyacrylic acid (a derivative of which is used for
de-mineralizing water) the nanocrystals arrange to form a fibrous structure
which is clearly visible by electron microscopy (see figure).

To bionically oriented material scientists, the fact that crystal shapes can be controlled by chaperone additions is an indication of self-organization. In the scientific technical branch of bionics experimental systems are modelled upon nature. Billions of years ago, self-organization enabled the inanimate
components of the primordial soup to form more complex aggregates: the
beginning of life! Living beings are able to form different structures such as
bones, teeth or pearls, all from the same chemicals, by biomineralization.
Scientists aim to mimics such conditions in order to produce new, highly
optimized materials by environment-friendly processes.

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