Recent progress in nonstoichiometric step-growth polymerization

According to the theory established by Carothers and Flory, stoichiometric control of monomers is necessary for efficient step-growth polymerization of AA-type and BB-type monomers in a single-phase solution. This review examines recent progress in synthesizing high-molecular-weight polymers via atypical nonstoichiometric step-growth polymerization (NSSP). The reactive intermediate mechanism (RIM) and intramolecular catalyst transfer (ICT) systems are essential for efficient NSSP, generating polymers with much higher molecular weights than theoretically predicted. NSSP systems provide many advantages in fine synthetic technologies for producing complex multifunctional polymers suitable for specific applications.