1493_ Uncovering the New World Columbus Created - Charles C. Mann [140]
Neither Goodyear nor Hancock had any idea why sulfur stabilized rubber—or why, for that matter, unadulterated rubber bounced and stretched. Nineteenth-century scientists found bouncing balls exactly as mystifying as sixteenth-century Spaniards. Stretch a thin hoop of iron: it will elongate slightly, then snap in two. A rubber band, by contrast, can stretch to three times its ordinary length, then return to its original shape. Why? And why did sulfur stop rubber from melting in the summer? “Nobody knew,” Coughlin told me. “It was a huge puzzle. And it was made harder by the fact that a lot of chemists didn’t really want to study it.”
The last half of the nineteenth century was a heady time for chemistry. Researchers were deciphering the underlying order of the physical world. They were placing the chemical elements into the periodic table, discovering the rules by which atoms combine into molecules, and learning that molecules could form regular crystals with structures that could be precisely identified.
Nowhere in these tidy intellectual schemes was a place for rubber. Chemists couldn’t make it form crystals. Worse, many standard chemical tests on rubber produced nonsensical answers. The analyses demonstrated that each rubber molecule was made up of carbon and hydrogen atoms. No problem there. But they also indicated that the carbon and hydrogen were piled up into jumbo-sized molecules made up of tens of thousands of atoms. To most chemists, this was absurd—molecules are the fundamental building blocks of chemical compounds, and no fundamental building block should be that big.
The obvious conclusion, chemists said, is that rubber must be a colloid: one or more compounds finely ground up and dispersed throughout other compounds. Glue is a colloid; so are peanut butter, bacon fat, and mud. Because colloids aren’t one substance but a mishmash of many different substances, they have no fundamental constituents. Looking for one would be like trying to find the molecular building blocks of a garbage heap. The chemistry of rubber was, one German researcher scoffed, Schmierenchemie. Literally, Schmierenchemie means “grease chemistry,” though Coughlin told me it might be better translated as “the chemistry of the gunk on the bottom of a test tube.”
Nonetheless, a few chemists ignored the disdain of their colleagues for rubber, prominent among them Hermann Staudinger, then at the Swiss Federal Institute of Technology in Zurich. A well-known researcher, he had already derived the chemical formulae for the basic flavors in coffee and pepper. (It is not unfair to charge Staudinger with inflicting instant coffee on the world.) Sometime during the First World War, he jumped into the entirely different field of rubber because of an intuitive belief that “high molecular compounds,” as he called them, did have basic building blocks, which were fantastically large molecules. Readers familiar with stories of successful scientific mavericks will not be surprised to learn that Staudinger attracted vehement opposition, that he kept piling up evidence for his hypothesis, and that the resistance grew irrational and vituperative. When he left Zurich to work at the University of Freiburg in 1925 he was denounced by colleagues during his farewell lecture. Presumably the antagonism was heightened by Staudinger’s penchant for picking fights. He once greeted the arrival of a rival’s book by gluing a denunciation—“This book is not a scientific work but propaganda”—onto the cover of the copy in his university library. In the end, though, Staudinger’s tale reached its denouement in the customary location: Stockholm, where he won the Nobel Prize for Chemistry in 1953.
Rubber and other elastomers, Staudinger showed, have molecules shaped like long chains.2