Ring‐Opening Polymerization Strategies for Degradable Polyesters

As minimizing the ecological effects of plastics is of ever greater importance, the replacement of certain conventional fossil-based plastics with biobased and degradable polymers has become an important strategy. Ring-opening polymerization (ROP) is a well-established, industrial polymerization technique especially suited for the production of aliphatic polyesters – a range of polymers susceptible to degradation through the ester linkages in their polymer backbones. While degradable polymers are certainly not limited to this category, this promising field is the focus of a lot of research. Notable polyesters made from ROP of cyclic lactones include the commodity bioplastics poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and poly(ϵ-caprolactone) (PCL). Herein we first provide a brief overview of the mechanisms and thermodynamics of ROP, as well as tools to enhance the biodegradability of ROP-based polyesters. Following that, this chapter reviews ROP of various standard and functionalized lactones of different sizes (four- to seven-membered rings), as well as the resulting polymer properties including their relation to degradability. Assessment methods of the latter are briefly discussed critically.