Simple In-Based Dual Catalyst Enables Significant Progress in ε-Decalactone Ring-Opening (Co)polymerization

A dual catalyst associating InCl3 and triethylamine was found to promote controlled ring-opening polymerization of epsilon-decalactone (epsilon-DL), a monomer derived from sustainable resources. Polydecalactones (PDL) of well-defined structures with M-n up to 30 000 g/mol (D approximate to 1.2) have been obtained free of catalytic residues under mild conditions (toluene, 3M, 60 degrees C, 1-20 h). Besides the typical ester end- capped PDLs, amide end groups have been installed thanks to the ability of the dual catalyst to perform with primary amines as initiators. Block PDL-b-PCL/PCL-b-PDL and random P(DL-r-CL) copolymers have been also prepared by sequential and simultaneous ROP with epsilon-caprolactone, respectively. The absence of undesirable transesterifications reactions, as apparent from NMR, SEC, and DSC analyses, enable the preparation of well-defined copolymers.