Polyester nanoparticles from macrolactones via miniemulsion enzymatic ring-opening polymerization

Aliphatic polyesters are the most used biodegradable polymers in biomedical applications. These polymers can be synthesized by two main routes: polycondensation and ring-opening polymerization. In this work, polyester nanoparticles were synthesized by an environmentally friendly process, enzymatic ring-opening polymerization (ε-ROP) of different 16-membered macrolactones (globalide (unsaturated) and ω-pentadecalactone (saturated)), catalyzed by a biocatalyst (free Candida antarctica B lipase) in aqueous miniemulsion. Reactions were conducted varying parameters as surfactant concentration, polymerization temperature (45 and 60 °C), and co-stabilizer type (hexadecane and crodamol, a medium chain saturated triglyceride). Saturated and unsaturated poly(macrolactones) were successfully synthesized via ε-ROP in miniemulsion, and weight average molecular weights of up to 23,200 g/mol were reached. Nanoparticles showed a “lemon-shaped” morphology, and their average diameter was affected by surfactant concentration, varying from 75 to 283 nm and from 218 to 436 nm for poly(globalide) and poly(ω-pentadecalactone), respectively. Melting points of 47–49 °C (unsaturated poly(macrolactones)) and 91–92 °C (saturated poly(macrolactones)) were obtained.