Ring-opening reactions of backbone epoxidized polyoxanorbornene

In this article, we report the synthesis of poly(oxanorbornene imide) (PONB) with internal epoxy groups (epoxidized-PONB₃₀) and its ring-opening reactions with various nucleophiles, such as amine, azide, and thiols. The ring-opening reactions with amines yielded the amine-hydroxyl PONBs in the range of 36-95% of functionalization depending upon the amine content per epoxy. An allylamine-hydroxyl functionalized PONB was further functionalized efficiently with 1-octanethiol by radical thiol-ene reaction. The ring-opening reaction of the main chain epoxy using thiols resulted in a lower functionalization than amines with a similar functional group (e.g., allyl). In addition, sodium azide together with NH₄Cl, was employed efficiently in the ring-opening reaction of the main chain epoxy, resulting in an azide/hydroxyl-functional PONB₃₀ with 53% efficiency, which was determined after a model copper-catalyzed azide-alkyne cycloaddition (CuAAC) experiment was carried out.