Pickles, Samuel Shrowder

Samuel Shrowder Pickles, (born April 15, 1878, Rochdale, Eng.—died Feb. 11, 1962, Bradford-on-Avon?), English chemist who proposed a chain (actually, very large ring) structure for rubber.

After receiving a bachelor’s degree in chemistry in 1903 from Owens College, Manchester, Pickles worked there on terpenes with William Henry Perkin, Jr. He received a doctorate (1908) from the Imperial Institute, London, for a study of rubber and vegetable fats and oils. The German chemist Carl Dietrich Harries, on the basis of his ozonolysis technique, had assumed that rubber consists of two isoprene units combined to form small eight-membered rings, which form larger aggregates held together by weak intramolecular forces. In 1906, at the York meeting of the British Association for the Advancement of Science, Pickles criticized Harries’ interpretation and proposed that rubber consists of long-chain molecules held together by Kekulé bonds—a structure now accepted for all polymers. In his work, published in 1910, he suggested that the two ends of a rubber molecule are linked together into a single ring consisting of at least eight isoprene units and that rubber molecules are not homogeneous but are composed of chains of different lengths. His basic structure was used by the German chemist Hermann Staudinger as the basis for his theory of very long polymer chains, or macromolecules.

In 1912 Pickles became chief chemist at George Spencer, Moulton & Co., Ltd. (a rubber firm now known as Avon Rubber PLC), in Bradford-on-Avon. There he worked primarily on processing crude rubber and manufacturing technical rubber products, including aircraft parts during World War II. He was concerned with new developments in rubber technology and introduced the use of thiokol (see polysulfide) and neoprene synthetic rubbers at Spencer, from which he retired in 1950.