2-Azetine Derivatives as a Class of New Monomers for Controlled Ring-Opening Metathesis Polymerization towards Polyenamides†

Nitrogen-containing polymers have found a wide myriad of applications in materials science and other different areas, and have attracted much attention towards the development of new synthetic methods. Ring-opening metathesis polymerization represents an area of great versatility and potential for the synthesis of highly functionalized polymers with low dispersity and control over molecular weight and architecture complexity. Expanding the scope of monomers through the incorporation of nitrogen atoms would further expand their utilities. In this work, a controlled synthesis of polymers with in-chain enamide moiety through ring-opening metathesis polymerization was developed by utilizing azetine derivatives as the monomers. Relatively short synthetic routes were designed and generated a panel of five monomers. The polymerization exhibited living characteristics, as linear relationship between molecular weights and degrees of polymerization and relatively narrow molar mass distributions were observed, which was further confirmed by successful diblock copolymers formation through sequential addition of two monomers. The resulting polymers that contain the enamide moiety within the backbone exhibited good stability and underwent facile degradation under acidic conditions.