The Discovery of Metallocene- and Metallocene-Like Addition Polymers

A personal account is given of the “early days” in the development of metallocene addition polymers in order to mark the 50th anniversary of the first report of a metallocene addition polymer, poly(vinylferrocene), by Arimoto and Haven at DuPont Inc. in 1955. Sometimes looking back, it seems like the early work was quaint and even obvious by today’s standards. However, this was not the case in the 1960s and ‘70s. These polymers seemed a strange departure from the “classic” world of polystyrene, polyacrylates, polyvinyl acetate, polyvinyl chloride, polybutadiene etc. The Polymer Handbook gave us no clue about how vinyl metallocenes might behave. Only through the (then) tedious synthesis of new monomers and a careful study of their homopolymerization kinetics and mechanism, their copolymerization reactivities and the characterization of the contributions the metal makes to their properties, was the stage set for the wider inclusion of organometallic addition polymers into mainstream macromolecular and materials science. Starting in the 1990s, and continuing today, an explosive growth of metal-containing macromolecular science and its extension to materials science has occurred. Herein, the early work in our laboratory is revisited. In the 1960s, metallocenes and organometal carbonyl compounds were a new exotic thrust of chemistry, merging inorganic and organic disciplines. However, few chemists had any thoughts of adapting this young field to polymers and materials. This is easily forgotten now, when practically every issue of numerous journals are filled with articles about polymers, films, multilayered devices etc. containing organic and inorganic hybrid substances (including metals) prepared by designer synthetic chemistry, self-assembly or biologically inspired routes. We have certainly come a long way!