Hermann Staudinger: Father of macromolecular chemistry


In 1920, Hermann Staudinger, then professor of organic chemistry at the Eigen÷ssische Technische Hochschule in Zurich, created a stir in the international chemical community when he postulated that materials such as natural rubber have very high molecular weights. In a paper entitled "▄ber Polymerisation," Staudinger presented several reactions that form high molecular weight molecules by linking together a large number of small molecules. During this reaction, which he called "polymerization," individual repeating units are joined together by covalent bonds. This new concept, referred to as "macromolecules" by Staudinger in 1922, covered both synthetic and natural polymers and was the key to a wide range of modern polymeric materials and innovative applications. Today, the molecular architectures of synthetic polymers and biopolymers are tailored with high precision to meet the demands of modern technology. The products of polymer chemistry are diverse, from food packaging, textile fibers, auto parts, and toys, to membranes for water desalination, carriers used in controlled drug release, and biopolymers for tissue engineering.

Staudinger's concept, however, represented a strong challenge to his contemporaries. The scientific community was very reluctant to admit the existence of extremely large compounds with molecular weights exceeding 5000. Instead, micelle-type aggregates, as observed for soap molecules, were considered to account for the unusual properties of such materials. Moreover, some scientists were convinced that the size of a molecule could never exceed the size of the unit cell, as measured by X-ray crystallography.

Staudinger, following the scientific tradition of classical organic chemistry, presented sound experimental evidence to support the existence of high molecular weight polymers. He selected natural rubber as the model system because Carl Harries and Rudolf Pummerer had suggested independently that natural rubber consisted of aggregated small cyclic polyisoprene units via "partial valencies" associated with the double bonds. Such aggregates should have been destroyed when the double bonds were removed by hydrogenation. Staudinger's hydrogenation experiments showed that hydrogenated rubber was very similar to normal unsaturated rubber.

During the late 1920s, Staudinger provided additional evidence based on viscometry to confirm that molecular weights remained unchanged during chemical modification of polymers. Despite the impressive experimental evidence, Staudinger continued to encounter very strong opposition for nearly two decades from leading organic chemists. For instance, Heinrich Wieland, 1927 Nobel laureate in chemistry, wrote to Staudinger, "Dear colleague, drop the idea of large molecules; organic molecules with a molecular weight higher than 5000 do not exist. Purify your products, such as rubber, then they will crystallize and prove to be low molecular compounds!" In his autobiography, Staudinger commented: "My colleagues were very skeptical about this change, and those who knew my publications in the field of low molecular chemistry asked me why I was neglecting this interesting field and instead was working on a very unpleasant field and poorly defined compounds, like rubber and synthetic polymers. At that time the chemistry of these compounds often was designated, in view of their properties, as Schmierenchemie ('grease chemistry')."

Staudinger never ceased to promote his concepts of polymer sciences, despite his colleagues' mistrust of many of his methods and results. In lively discussions, he eloquently defended his ideas against all attacks using his ingenuity, persistence, and pronounced enthusiasm. By the end of the 1920s and during the 1930s, Staudinger's macromolecular concept found increasing acceptance by other chemists. Although some of his opponents still maintained their objections, his concept was already being applied in industrial processes. At long last, on December 10, 1953, Staudinger received his reward for the concept of macromolecules and his prolonged effort to establish the science of large molecules when he was awarded the Nobel Prize for chemistry.


 

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Hermann Staudinger: Father of macromolecular chemistry | Staudinger's life and career | Political concerns
Industrial significance of polymer science | Macromolecules: A bridge between material sciences and life sciences
Hermann Staudinger's life and achievements | Landmark designation

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