Metal-free catalyzed ring-opening polymerization and block copolymerization of ω-pentadecalactone using amino-ended initiators

Abstract

Metal-free catalysis was successfully applied to polymerize ω-pentadecalactone (PDL) by ring-opening polymerization (ROP) using several amino-ended initiators, namely hexylamine, allylamine and O,O′-bis(3-aminopropyl)diethylene glycol. This polymerization method was suitable to prepare telechelic polyesters carrying functional-end groups. The technique was then extended to the synthesis of block copolymers by ROP of PDL using bisamino-ended poly(ethylene glycol) (Mn = 2600) as macroinitiator. PPDLx-PEG56-PPDLx triblock copolymers with Mn ranging between ∼4000 and ∼90,000 g ·mol−1 were synthesized and extensively characterized by NMR, DSC, TGA and XRD. The amphiphilic copolymers thus produced were demonstrated to be able to self-assemble in nanoparticles with average diameters of ∼100–200 nm and morphologies highly depending on blocks lengths. The described synthetic route distinguishes in providing “clean” amphiphilic copolymers, which are attractive candidates for biomedical applications.