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

[Display omitted] •ROP of pentadecalactone initiated by amino-ended compounds and catalyzed by organic bases or enzymes is described.•The described method allows obtaining polyesters absent of metallic contaminants.•Triblock copolymers of ethylene glycol and pentadecalactone with controlled polyester block lengths were successfully synthesized by this method.•These triblock copolymers were able to form structured amphiphilic nanoparticles of interest as biomaterials. 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.