Synthesis and Solution Properties of PCL-b-PHPMA Diblock Copolymers Containing Stable Nitroxyl Radicals

Abstract

This work focuses on the synthesis and the aqueous solution properties of novel amphiphilic PCL-b-PHPMA diblock copolymers possessing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) stable radicals covalently conjugated to the hydrophobic poly(e-caprolactone) (PCL) block. A new synthetic approach (a four-step pathway) combining ring-opening polymerization (ROP), carbodiimide chemistry (DCC method), a reversible addition–fragmentation chain transfer (RAFT) polymerization technique, and finally chemical oxidation was employed to successfully produce a series of TEMPO-containing PCL-b-PHPMA diblock copolymers for the first time. EPR spectroscopy was applied to verify successful oxidation of the synthesized diblock copolymers and to investigate the dynamics of the polymer chains before and after micellization. The diblock copolymers self-assembled in PBS solution into spherical radical-containing nanoparticles (RNPs), which were characterized by 1H NMR spectroscopy, dynamic (DLS), static (SLS) light scattering, ...