The synthetic material known as silicone, a versatile polymer, is found throughout modern life, from medical implants and kitchenware to sealants and high-performance lubricants. Its unique properties, including thermal stability and chemical inertness, have made it indispensable across countless industries. The history of silicone spans over a century, beginning with the identification of its foundational element and culminating in the industrial synthesis of this revolutionary material.
Silicon vs. Silicone: Clarifying the Chemical Distinction
The similar names of silicon and silicone often cause confusion, yet they describe two fundamentally different substances. Silicon (Si) is a naturally occurring chemical element, a metalloid found at number 14 on the periodic table. It is the second most abundant element in the Earth’s crust, commonly found bonded to oxygen in compounds like silica, the main component of sand and quartz. Pure elemental silicon is a hard, gray solid used extensively in the electronics industry as a semiconductor.
Silicone, conversely, is a synthetic polymer, or a large, man-made molecule. It is characterized by an inorganic backbone composed of alternating silicon and oxygen atoms, known as siloxane bonds. Organic groups, typically methyl groups, are attached to the silicon atoms along this chain. This combination gives silicone its unique properties, allowing it to exist as oils, gels, rubber, or resins.
The Elemental Foundation: Discovering Silicon
The path to creating silicone began with the isolation of its namesake element, silicon. For centuries, the raw material, silica, was known, but separating the element from its compounds was difficult due to silicon’s strong chemical affinity for oxygen.
The first successful isolation of amorphous silicon is credited to Swedish chemist Jöns Jacob Berzelius in 1824. Berzelius achieved this by heating potassium metal with potassium fluorosilicate and then purifying the resulting brown powder. Berzelius was the first to properly characterize the element, providing the raw chemical building block needed for the synthetic polymer decades later.
The Polysiloxane Era: The Synthesis of Silicone
The true breakthrough for the material we call silicone occurred in the early 20th century through the work of English chemist Frederic Kipping. Kipping pioneered the study of organosilicon compounds and, in 1901, coined the term “silicone” to describe his polydiphenylsiloxane compounds. Kipping’s extensive work established the theoretical groundwork for this new class of materials.
The leap to industrial production came in the 1930s and 1940s, driven by the need for advanced materials for the war effort. Dr. James Franklin Hyde at Corning Glass Works researched commercial silicones, focusing on heat-resistant resins. Separately, Eugene G. Rochow at General Electric and Richard Müller in Germany independently developed a more efficient direct synthesis method in 1940. This method, known as the Müller-Rochow synthesis, made large-scale production economically feasible by reacting elemental silicon and methyl chloride.
Why Silicone Mattered: Early Industrial Applications
The industrial synthesis of silicone was rapidly commercialized due to its unique combination of properties. The material’s silicon-oxygen backbone provided exceptional thermal stability, allowing it to maintain integrity across a wide temperature range, up to 250°C. This heat resistance, combined with excellent electrical insulating properties, made it immediately valuable to the military.
The joint venture between Dow Chemical and Corning Glass Works, known as Dow Corning, was formed in 1943 to manufacture these new polymers. Their first commercial product, Dow Corning 4 Compound, was a grease-like sealant used to protect the ignition systems of Allied aircraft. This prevented electrical arcing at high altitudes and enabled reliable flight during World War II. Other applications included high-temperature lubricants and specialized resins for insulating glass cloth.