Versatile Ring-Opening Copolymerization and Postprinting Functionalization of Lactone and Poly(propylene fumarate) Block Copolymers: Resorbable Building Blocks for Additive Manufacturing

Additive manufacturing has the potential to change medicine, but clinical applications are limited by a lack of resorbable, printable materials. Herein, we report the first synthesis of polylactone and poly­(propylene fumarate) (PPF) block copolymers with well-defined molecular masses and molecular mass distributions using sequential, ring-opening polymerization and ring-opening copolymerization methods. These new copolymers represent a diverse platform of resorbable printable materials. Furthermore, these polymers open a previously unexplored range of accessible properties among stereolithographically printable materials, which we demonstrate by printing a polymer with a molecular mass nearly 4 times that of the largest PPF homopolymer previously printed. To further demonstrate the potential of these materials in regenerative medicine, we report the postprinting “click” functionalization of the material using a copper-mediated azide–alkyne cycloaddition

Dual Catalysis for Selective Ring-Opening Polymerization of Lactones: Evolution toward Simplicity

Much work has been directed to the design of complex single-site catalysts for ring-opening polymerization (ROP) to enhance both activity and selectivity. More simply, however, cooperative effects between Lewis acids and organocatalytic nucleophiles/Lewis bases provide a powerful alternative. In this study we demonstrate that the combination of <i>N</i>-heterocyclic carbenes, 1,8-diazabicycloundec-7-ene (DBU) and 4-dimethylaminopyridine (DMAP) with simple Lewis acids enables the ROP of the macrolactone pentadecalactone in a rapid and efficient manner. Remarkably, regardless of the nature of the nucleophile, the order of activity was observed to be MgX₂ ≫ YCl₃ ≫ AlCl₃ and MgI₂ > MgBr₂ > MgCl₂ in every case. The minimal influence of the organobase on polymerization activity allows for the use of simple and inexpensive precursors. Furthermore, extension of the study to other cyclic (di)­ester monomers reveals the choice of Lewis acid to lead to monomer selective ROP activity and hence control over copolymer composition by choice of Lewis acid. This approach could lead to the realization of complex polymer structures with tunable physical properties from simple catalyst combinations

Polymers from macrolactones: from pheromones to functional materials.

Recent advances in the ring-opening polymerization (ROP) of macrolactones (MLs) have afforded access to novel, potentially degradable polymeric materials featuring long aliphatic chains. These developments extend the synthetic robustness and versatility of ROP to a greater range of interesting monomers, many of which can be derived from sustainable or renewable feedstocks, to access polymeric materials boasting a diversity of properties and potential applications. This review discusses current strategies to catalyse the ROP of MLs, comparing and contrasting them with those known for the ROP of small and medium sized lactones, and highlights recent developments in the preparation, functionalization, and application of materials featuring poly(macrolactone)s (PMLs)