Radical Polymerization of Methylene Heterocyclic Compounds: Functional Polymer Synthesis and Applications

Synthetic polymers sustain a wide range of applications but the quest for further sophistication and functionalization of polymers remains topical to improve their scope and performance.In this respect, the radical polymerization of exo-methylene heterocyclic compounds (MHCs) is attractive.Compared to the classical acyclic vinyl monomers constrained to the vinyl-type polymerization process, MHCs can undergo different polymerization modes, namely the radical ring-retaining polymerization (rRRP) and the radical ring-opening polymerization (rROP).In rRRP, the cyclic group is preserved and inserted as side group of the polymer backbone offering a myriad of post-polymerization modifications whereas functional groups are incorporated within the backbone of linear polymers and confer them some degradability in rROP.Herein, recent advances in the radical polymerization of MHCs as well as the variety of macromolecular structures and applications it offers are highlighted.The reversible deactivation radical polymerization of MHCs leading to well-defined MHC-based macromolecular architectures, including multifunctional, stimuli-responsive and degradable polymers, is also discussed.The review emphasizes the current limitations of the radical polymerization of MHCs as well as future prospects including the development of innovative bio-based MHCs.Overall, the radical polymerization of MCHs represents a powerful macromolecular engineering tool and a broad field of exploration for polymer chemists.clothing, adhesives, etc, to highly engineered polymers applied in medical, electronic and photonic technologies, to name a few.After several decades of progress, efforts to make polymerization techniques more efficient, versatile and sustainable, remain timely owing the increasing demand for innovative functional polymers able to address the requirements of today's applications.Free radical polymerization (FRP) is one of the most widely used polymerization methods.It proceeds through a classic chain growth process and generates high molecular weight polymers.Its robustness, tolerance to moisture and high compatibility with many functional groups, make radical polymerization a tool of choice for producing synthetic polymers, especially in industry. 1However, the inherent irreversible termination reactions leading to illdefined structures prevent conventional FRP from being further used in cutting-edge applications which often require precise polymer architectures, predictable molecular weight and/or controlled chain-end functionalities.In the past decades, the limitations of conventional free radical polymerization have been overcome by the development of controlled radical polymerization, preferentially referred to as reversible deactivation radical polymerization (RDRP). 2 In the latter, a controlling agent allows the temporary deactivation of the propagating radicals in the form of a dormant species which limits the extent of irreversible reactions and prolongs the life time of radicals.In other words, a dynamic equilibrium rapidly establishes between a small amount of active radicals and a large amount of dormant species. 3In this case, fast and quantitative initiation reaction associated to a low propagation rate compared to the deactivation rate result in polymers with predictable molecular weights, low dispersity and high chain-end fidelity.This also paved the way to polymer with complex architectures including block, gradient, graft, star-shaped and telechelic copolymers to name a few.There are several RDRP techniques This is the authors' version of the article published in Polymer Reviews.Changes were made to this