What links natural products like rubber and cellulose with artificial plastics is that they are made up from extraordinarily large molecules. The idea of how these molecules originate or are formed was believed to be set in stone, until Hermann Staudinger provided an audacious concept that in time helped to unravel their structural secrets.
Staudinger’s proposal about the structure of large molecules appeared in a paper published in 1920, during the course of his studies on the chemistry of rubber. He argued that he found little evidence for the conventional wisdom, which stated that molecules can only reach a certain maximum size, and that somehow small molecules clump together in glue-like aggregates to give the false impression that they are giant molecules. Contrary to this view, Staudinger proposed that these molecules are in fact made from giant chain-like compounds, which are formed by links of short repeating molecular units joined through chemical interactions, and that these could be constructed to almost any length.
Working against a constant background of intense scepticism, Staudinger spent almost a decade meticulously piecing together indirect evidence for what he termed macromolecular compounds; for instance, by looking at the way they reacted and their viscosity in solution. Direct evidence to support Staudinger’s hypothesis finally arrived when Herman Mark visualized long chains of repeated units using X-rays, and Wallace Carothers showed that artificial materials like nylon and polyester could be stitched together from repeated small units using chemical reactions regularly carried out in the laboratory.
Staudinger’s pioneering ideas laid the foundation for the modern plastics industry, with chemists able to modify elements in chemical chains to create new artificial materials for a host of uses. Staudinger’s work also provided the basis for studying the chemistry of the macromolecules found in living organisms, such as the proteins and DNA that are the vital building blocks for all life on Earth.