4.22 - Nonlinear Macromolecules by Ring-Opening Polymerization

Abstract

Ring-opening polymerization (ROP) is a well-established method for the controlled synthesis of linear polymers, which can be found in various everyday applications. However, during the past decades, there has been an increasing interest in the generation of nonlinear highly branched polymers, profiting from the fascination created by the structurally perfect dendrimers. The applicability of various heterocyclic monomers renders the ring-opening multibranching polymerization (ROMBP), a versatile tool for the generation of multifunctional hyperbranched polymers. First, the historical key steps leading to the development of ROMBP are described, which is the basis for the controlled synthesis of nonlinear macromolecules. Subsequently, specific concepts in ROMBP, namely cationic, anionic, and catalytic polymerizations, are detailed. In particular, anionic multibranching polymerizations are powerful tools for the controlled synthesis of hyperbranched polyether polyols, which are interesting candidates for applications ranging from the biomedical field to catalysis. In the last section, the recent trends in the generation of complex macromolecular architectures containing nonlinear polymers synthesized by ROMBP as building blocks, for example, linear-hyperbranched hybrid structures or conjugates with biologically relevant molecules, are discussed.