In order to validate the proposed mechanism and assess the chemical structure of furan-based copolyesters, we conducted NMR and FTIR analyses (Figure and 3). Detailed 1 H, C NMR, and FTIR spectra of representative furan-based copolyesters are provided in the Supporting Information (SI) (Figure -S4 for NMR and S5-S8 for FTIR). Additionally, the calculation of chemical composition and molecular weight has been included in the SI and summarized in Table . For further clarity, detailed NMR assignments are provided as follows: