Phosphorus pentoxide as a cost-effective, metal-free catalyst for ring opening polymerization of ϵ-caprolactone

Abstract

The ring-opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) using phosphorus pentoxide (P2O5) as a metal-free catalyst and isopropanol (iPrOH) as initiator resulted in the preparation of poly(ϵ-caprolactone) with narrow weight distribution. NMR spectroscopy analyses of the prepared PCL indicated the presence of the initiator residue at the end of the polymer chain, implying the occurrence of the ϵ-CL-catalysis ROP through a monomer activation mechanism. Kinetic experiments confirmed the controlled/living nature of ϵ-CL ring-opening catalyzed by phosphorus pentoxide. The commercial availability of phosphorus pentoxide and its easy-handling provide additional opportunities for polymer synthesis and nanocomposite manufacturing.