Degradable\nPolymer Architectures Based on Polyphosphonate,\nPoly(2-oxazoline), and Poly(2-oxazine)

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