In 1947, Michael Szwarc was pursuing his academic career in physical chemistry at the Univ. of Manchester, England. His interest in the strength of individual chemical bonds led him to investigate a class of aliphatic carbon-hydrogen bonds in which the carbon was directly attached to a benzene ring. While doing so, he heated gases of the simplest compounds having both benzene and carbon — toluene and the xylenes — to high temperatures. He monitored both the decomposition products and rates of decomposition as a function of temperature.

With p-xylene only, a tan-colored deposit formed in the cooler reaches of his glassware. The material has been described as a thin, € imsy, tube-shaped mass, “the skin of a small snake.”

Szwarc correctly deduced that this … lm had been formed by polymerizing reaction products of the p-xylene, called p-xylylene. He also noticed the new polymer’s physical properties and chemical inertness. This serendipitous polymerization was the world’s … rst vapor deposited poly(paraxylyene). Today its purer colorless form is called parylene N.

A few years later, William Franklin Gorham at Union Carbide Corp. continued the research on parylene. By 1967, this work led to the availability of a new polymeric coating. “Parylenes” was the term used to describe both a new family of polymers and the vacuum-deposition process for applying them. In fact, Union Carbide developed over 20 types of parylene, but only three were deemed commercially viable.

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