Multistep Growth “Polymerizations”

Chain‐growth and step‐growth polymerizations are the two main mechanisms that are classically used to synthesize polymers. In this article, a third approach that is usually not listed in polymer textbooks is described, namely multistep growth “polymerization.” This synthetic strategy does not proceed in one pot as the aforementioned ones but relies on a series of distinct chemical reactions. It includes different types of stepwise syntheses such as solid‐phase iterative chemistry, exponential iterative growth, and dendrimer synthesis. Although these methods are more time‐consuming and experimentally demanding than chain‐growth and step‐growth polymerizations, they allow a very high level of control over macromolecular structure. In particular, they enable a perfect control over molecular parameters such as chain‐length, molecular weight, molecular weight distribution, tacticity, and comonomer sequence. Here, the common “multistep growth” mechanism shared by all these approaches is described and critically analyzed. Furthermore, the structure, properties, and applications of the formed polymers are discussed. This manuscript can serve as a reference guide to understand and rationalize the emerging domain of precision polymer synthesis. Two main mechanisms are generally used for the preparation of synthetic polymers, namely chain‐growth and step‐growth polymerizations. In this manuscript, a third generic mechanism called multi‐step growth “polymerizations” is proposed. It includes stepwise methods that are imported from organic synthesis such as solid‐phase synthesis, multiplication synthesis, and dendrimer synthesis. These approaches allow synthesis of macromolecules with highly defined molecular structures.