The FT-IR measurements also permitted us to confirm that the chemical structures of the obtained macromonomers were consistent with the assumed reaction mechanism and with our previous work where DBTDL was used as catalytic system. Overall, all of the obtained spectra were similar, indicating that the macromonomers obtained using the new catalysts had the same chemical structures. A representative FT-IR spectrum of PrBiHex_2 macromonomer, as compared to the starting material, polyester polyol Priplast-1838, is presented in Figure .