Karl Ziegler

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German chemist (1898–1973)

Ziegler was born at Helsa in Germany, the son of a minister. He received his doctorate from the University of Marburg in 1923 and then taught at Frankfurt, Heidelberg, and Halle before becoming director of the Max Planck Institute for Coal Research in 1943. In 1963 he was awarded the Nobel Prize for chemistry with Giulio Natta for their discovery of Ziegler–Natta catalysts.

One of the earliest plastics, polyethylene, was simply made by polymerization of the ethylene molecule into long chains containing over a thousand ethylene units. In practice, however, the integrity of the chain tended to be ruined by the development of branches weakening the plastic and endowing it with a melting point only slightly above the boiling point of water.

In 1953 Ziegler introduced a family of catalysts that prevented such branching and produced a much stronger plastic, one which could be soaked in hot water without softening. The catalysts are mixtures of organometallic compounds containing such metallic ions as titanium and aluminum. The new process had the additional advantage that it requires much lower temperatures and pressures than the old method.

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