Polymer
A polymer is a high molecular-weight material, either synthetic or natural, that is composed of repeating units called monomers covalently bonded in a linear fashion. This definition rests largely upon the research of Hermann Staudinger, one of the founders of polymer science and the recipient of the 1953 Nobel Prize for chemistry. He led the fight to prove that molecules with molecular weights of over 5,000 existed. His intuitions were correct and he succeeded in proving his considerable opposition wrong.
Staudinger was born in 1881. He attended the Universities of Munich and Halle, Germany, and received his doctorate in chemistry in 1903. He taught at various institutions before settling at Freiburg, Germany, in 1926 where he stayed until his retirement in 1951. He died in 1965. Staudinger became intrigued by large molecules when he began to study the structures of rubber. He first expressed his opinion that covalent bonds were an integral part of macromolecules in a paper delivered to the Swiss Chemical Society. Some opposition arose from the fact that Staudinger proposed that the ends of the long chains were not saturated, that is, they would still be able to bond to other atoms because not all of their electrons were being used in bonds.
Staudinger and his students began to systematically experiment with the formation of polymers. They eventually succeeded in proving what are now accepted as basic facts: Polymers are chain molecules with normal valence bonds terminated by characteristic groups rather than unsaturated groups. They also showed that these groups can be used to determine the length of the carbon chain. Staudinger moved on to study what we now call condensation reactions. One major breakthrough was documented by a paper published in 1929 by Staudinger, Brunner, Frey, Garbsh, Signer, and Wehrli. The paper detailed experimentation that proved that polymerization involves activated monomers to which other monomers are added. Further research by Staudinger and Kohlshutter led to more refinements in the study of addition polymerization.
Wallace Carothers (1896-1937), while conducting research for the Du Pont Company, confirmed Staudinger's view of polymers and distinguished between addition and condensation reactions. Carothers went on to develop neoprene and nylon. John Whinfield (1901-1966) and J. T. Dickson built on his research to discover polyester. Additional research by Karl Ziegler (1898-1973) showed that organometallic compounds could be used as catalysts in addition reactions. Ziegler also succeeded in developing a room temperature reaction that used organoaluminum, metal chloride, and ethylene to form high molecular weight polyethylene. Guilio Natta (1903-1979) built on Ziegler's research and used organometallic compounds to control the stereochemistry of polymers to form optically active polymers from optically inactive monomers. Many scientists have contributed to our understanding of polymers, but Staudinger, Carothers, Ziegler, and Natta have contributed most in this area through basic research.
Originally, most polymers were developed to mimic the behavior of natural products such as wool, cotton, silk, ivory, and rubber. Soon, however, plastics were developed which were totally synthetic creations. A variety of other polymeric compounds were also produced such as elastomers, fibers, coatings, and adhesives. These materials revolutionized certain areas of industry. Consequently, polymers are found throughout all aspects of our lives and new polymers are being developed everyday. Their commercial introduction and their applications will continue to grow.
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