Imine-based multicomponent polymerization: Concepts, structural diversity and applications

Abstract

Multicomponent reactions (MCRs) are remarkable one-pot combinatorial synthetic tools involving at least three reactants whose nearly all atoms are incorporated in the final product. The development of these high atom-efficient reactions considerably raised the level of molecular complexity and diversity in the last decades. Nowadays, MCRs are no longer confined to organic synthesis and have seen their use extended to polymer science. The latter tend to occupy an increasingly important place in polymer synthesis and sustain the eager demand for innovative and structurally diverse macromolecules involved in highly valued applications. While MRCs can serve for monomer synthesis and post-polymerization modification, they offer their full potential in one-pot step-growth polymerizations, namely multicomponent polymerizations (MCPs). This review provides a comprehensive and up to date overview of the imine-based MCPs and highlights their great potential for the design of advanced linear, hyperbranched and crosslinked polymers. The focus is placed on MCPs involving imines, the most common and valuable MCRs’ intermediates which are prone to various nucleophilic attacks and give access to a great variety of products. The efficiency, combinatorial feature, substrates versatility and limitations of these imine-based MCPs as well as the polymer diversity they offer are discussed in detail. Some MCPs can also be combined in one-pot to afford unique and highly complex structures. At this stage, several multicomponent step-growth polymerizations are already mature enough to sustain cutting-edge applications in biomedicine, energy, environment and catalysis amongst others. The existing challenges to be addressed are identified and the future research directions are discussed accordingly. MCPs, in particular imine-based ones, will undoubtedly further grow and confirm their status of essential macromolecular engineering tools in the future.