Degradable Polymer Architectures Based on Polyphosphonate, Poly(2-oxazoline), and Poly(2-oxazine)

Degradable polymers are vital, as they reduce environmental impact, conserve resources, and offer biocompatibility for medical applications. Polyphosphoesters (PPE) contain ester bonds in the backbone that enable hydrolytic degradation and are compatible with biological systems. Due to this advantage, PPE have been extensively studied, with efforts to also combine it with other polymer classes. In this study, we demonstrate the successful use of poly(2-oxazoline)s (POx) and poly(2-oxazine)s (POz) as macroinitiators for the ring-opening polymerization of 2-ethyl-2-oxo-1,3,2-dioxaphospholane (EtPPn). POx and POz have been gaining emerging attention in both industrial and biological applications due to their unparalleled synthetic versatility. Therefore, by combination of PPE with this polymer class, the degradability of the former and the unique properties of POx and POz can be exploited for numerous applications. We present a library of novel water-soluble block copolymers and polymeric brushes that combine poly(2-ethyl-2-oxo-1,3,2-dioxaphospholane) (PEtPPn), poly(2-ethyl-2-oxazoline) (PEtOx), and poly(2-n-pentanol-2-oxazine) (POzOH). The accelerated degradation of the copolymers is assessed by hydrolysis experiments at pH 11.2 and pH 8.8. The study illustrates that the degradation rate of these novel architectures is modifiable and can be adjusted accordingly to suit different applications.