Ring-Opening Polymerization (ROP) of Phenylalanine Derived O-Carboxyanhydride (OCA) Using Different Mono- and Bimolecular Conjugated Catalysts and Amino or Alcohol Initiators

In the present study, we investigated the activity of four groups of organocatalysts, initiators, and combined catalysts-initiators, through bimolecular reactions with linked catalysts-initiators operating during the polymerization, through a monomolecular pathway in ring-opening polymerization of O-carboxyanhydrides (OCAs) derived from phenylalanine, in the presence or absence of the cocatalyst 4-dimethyl aminopyridine (4-DMAP). The polymerization of the Phe-OCA process was measured by gel permeation chromatography and combined molecular weight determinations in different solvents and temperatures, at various concentrations of initiators and with/without the cooperative effect of cocatalysts. NMR estimated the rate constants of polymerization. Dimethylaminoethyl amine and dimethylaminopropyl amine, without 4-DMAP, were found as highly active catalysts for a more controlled polymerization reaction. 4-(Hydroxymethyl)-1H-imidazole, in the presence of 4-DMAP, was the most effective catalyst for the uncontrolled polymerization reaction of Phe-OCA. Phe-OCA polymers were found biocompatible in vitro proposing applicability for biomedical materials. The present study highlights different catalysts and has important implications for the synthesis of polymeric polyesters in translational medicine.