We saw last week how the discovery of Saturn's moon Iapetus posed a question that took centuries of research before it could be answered. It is either this way, where an unanswered phenomenon leads to research, or it could be that research is driven with a certain objective in mind. What we'll be looking at this week, the invention of neoprene, belongs to the latter category.
Interest in synthetic rubber dates back to the 19th century. It was identified that isoprene, a liquid hydrocarbon, is the main constituent of natural rubber and what followed were attempts to transform isoprene into rubber, without success.
The shortcomings of natural rubber (read as lack of resistance to oil, oxygen and extreme temperatures) and the growing dependence on elastic substances meant that the search for synthetic rubber was well on its way in the early years of the 20th century.
Germany was forced into the first large-scale production of a substitute for rubber during World War I, but methyl rubber was nowhere as good as natural rubber. The search for a commercially practical synthetic rubber, in short, was still on.
Elmer Bolton, Julius Nieuwland, Wallace Carothers and Arnold Collins, chemists working with E. I. DuPont de Nemours, were the men who finally made it happen. The increasing price of rubber meant that Bolton initiated a project to synthesise an elastic substance from acetylene. Bolton was taken by a presentation on acetylene reactions by Nieuwland, a priest-scientist working as a professor with the University of Notre Dame, and brought him on board.
Along with Nieuwland, scientists at DuPont were able to isolate divinyl acetylene (DVA) and monovinyl acetylene (MVA), but were still no closer at obtaining their required results. Carothers, who was exploring polymers since his arrival at the company in 1928, decided to look into DVA.
Carothers appointed his assistant Collins to conduct experiments and suggested that he explore the reaction between MVA and hydrogen chloride. On April 17, 1930, Collins noted that the liquid that his experiments had yielded had in fact solidified into a rubbery substance.
When he dropped this rubbery substance, it bounced back. It also exhibited resistance to oil, wax and grease apart from withstanding temperatures in the range -50°C to 120°C. It was introduced by the company as Duprene, the first synthetic rubber, on November 2, 1930.
By 1937, the generic name neoprene was adopted, to indicate that it was an ingredient and not a finished product in itself. During World War II, when Japan took control of most of the natural rubber plantations in Southeast Asia, America and its allies had to lean on neoprene. And once the war was over, this new material, which had also helped Carothers put polymer studies on a firm footing, was made available as a synthetic substitute to natural rubber.
A.S.Ganesh can be reached at ganesh.a.s@thehindu.co.in
