Video Upload Options

When two or more monomers are incorporated under anionic chain-growth conditions, the process is anionic copolymerization. A nucleophilic initiator generates a carbanionic or oxanionic chain end that adds monomers according to their relative electrophilicity and the ion-pairing state of the active center. Sequential monomer addition produces block copolymers; simultaneous feeding can yield statistical, gradient, or, with suitable reactivity ratios, alternating sequences. Anionic copolymerization of aziridines with ethylene oxide generates amphiphilic multiblock architectures from a single living chain end ^[1]. Related one-pot or stepwise protocols assemble alternating (AB)n multiblock copolymers of high molecular weight in a reduced number of additions ^[2]. Copolymerization of epoxides with carbon dioxide produces polycarbonate segments that can be extended into diblock structures while retaining a monomodal, ultrahigh-molar-mass distribution ^[3]. The concept is bounded as an ionic copolymerization: both (or all) monomers propagate through anionic active centers, in contrast to radical or coordination copolymerizations whose chemoselectivities and termination modes differ.