The copolymerization of styrene and maleic anhydride has received significant attention in academia as well as in industry. Nevertheless, the underlying mechanism of the copolymerization is still a point of debate. In this paper, an overview is given that provides compelling evidence in favor of the penultimate unit model as the correct choice to describe the process of chain growth. In addition to that new developments in terms of living radical copolymerization of styrene and maleic anhydride are discussed from a mechanistic point of view.
