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Walter Bock (20 January 1895 – 25 October 1948)Death record Nr. 3271/Köln I for Ludwig Walter Robert Bock of Oct. 26, 1948, Landesarchiv NRW, Duisburg was a German chemist who developed styrene-butadiene copolymer by emulsion polymerization as a synthetic rubber (SBR).
Immediately after graduation he joined the army and served as an officer in World War I. He commanded an infantry company until he was wounded in July 1918. In October 1918 he began studying chemistry. After receiving his Ph.D. from the University of Göttingen in October 1921, Bock found employment as chemist at the Köln Rottweil AG in Premnitz. In the fall of 1924 Bock joined the Dr. Zellner laboratories in Berlin, where he took charge of the chemical-pharmaceutical department.Barbara Zimmermann, ed. "Vignettes from the International Rubber Science Hall of Fame (1958–1988): 36 Major Contributors to Rubber Science, A Biographical Collection", (Akron, OH: The Rubber Division of the American Chemical Society, 1989), "Walter Bock", pp. 145–151
Bock focused on emulsion polymerization, which had been already invented in 1912 by Kurt Gottlob (1881–1925)German patents 254672 (Jan. 26, 1912) and 255129 (Mar. 12, 1912), U.S. Patent 1149577 (Jan. 6, 1913) at Bayer, but had so far yielded no practical application. Walter BockGerman patent 511145 (Jan. 15, 1927) and his colleague Claus HeuckGerman patent 558890 (Jan. 9, 1927) independently improved the emulsion process by introducing new emulsifiers. Bock also discovered that peroxy compounds are effective initiators in the emulsion polymerization of conjugated diolefines. But Bock and Heuck failed to gain good, economically feasible synthetic rubbers by this process. Polymers of butadiene and isoprene had good elasticity after vulcanization, but were crumbly. Polymers of dimethyl butadiene had good tensile strength, but nearly no elasticity.
In the fall of 1928 Bock had the idea to copolymerize dimethyl butadiene with isoprene and butadiene, respectively, to combine the positive mechanical properties. The result was encouraging. Both synthetic rubbers had mechanical properties almost comparable with natural rubber.German patent 551968 (Feb. 13, 1929)
In spring 1929 Bock replaced dimethyl butadiene by styrene. The styrene-butadiene rubber (SBR), which he synthesized from styrene and butadiene as comonomers, was superior to natural rubber in abrasion properties and therefore especially useful for tire applications.German patent 570980 (Jul. 21, 1929), US-Patent 1938731 (July 10, 1930) The rubber was marketed with the brand name Buna S. Even today SBR is the most successful synthetic rubber in terms of trade volume (together with Polybutadiene (BR)).
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