Plastics surround our everyday lives, and the fact that they do is thanks largely to the innovations awarded the 1963 Nobel Prize in Chemistry. By bringing order to the manner in which plastics are created, Karl Ziegler and Guilio Natta established ways of making them significantly cheaper, stronger and more versatile.
Plastics are made up from tightly packed polymers, which are extremely long chains of atoms formed by joining small units of carbon-containing chemicals repeatedly end to end. Early methods for attaching these smaller monomer units together were unpredictable in that the resulting chains also contained random branches of chemicals, like a frayed rope, which affected characteristics like the strength of the final product. Karl Ziegler was testing possible new catalysts that could drive reactions to create neater chains, when he accidentally discovered that compounds containing aluminium and carbon in the presence of trace amounts of a transition metal element could achieve the task. Acting upon his fortuitous observation, Ziegler systematically tested a range of related compounds, until he arrived at a combination that could link together the small chemical monomer ethylene to form polyethylene chains that were longer and had fewer branches, and crucially could achieve this under less intense temperatures and pressures than the methods used at the time.
Giulio Natta looked at ways of developing this catalyst to stitch other monomers together. For instance, linking the monomer propene also created unwanted chemical attachments pointing in different directions, which made it difficult for these polymer chains to fit neatly on top of each other. Natta solved this problem by designing a variation of the catalyst in which the space through which a growing polymer chain progresses is shaped in such a way that it can only accept attachments aligned in a particular direction. Thanks to Ziegler and Natta's breakthroughs, the plastics business saw one of its most significant periods of innovation. Many new plastics were created, from the man-made fibres in clothes to the plastic bottles that we drink from, and for the first time chemists could create the type of complex polymers present in nature, most notably synthetic versions of rubber.
This Speed Read is supported by the Camille and Henry Dreyfus Foundation Special Grant Program in the Chemical Sciences.