This is the peer reviewed version of the following article: "Gustini, L., Lavilla, C., Janssen, W., Martínez de Ilarduya, A., Muñoz-Guerra, S.
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Green and selective polycondensation methods toward linear sorbitol-based polyesters: enzymatic vs. organic and metal-based catalysisLiliana Gustini [a,b] , Cristina Lavilla * [a] , William W.T.J. Janssen [a] , Antxon Martínez de Ilarduya [c] , Sebastián Muñoz-Guerra [c] , Cor E. Koning [a,d] Abstract: Renewable polyesters derived from a sugar alcohol, i.e. sorbitol, were synthesized by solvent-free polycondensation. The aim was to prepare linear polyesters with pendant hydroxyl groups along the polymer backbone. The performance of the sustainable biocatalyst SPRIN liposorb CALB and the organo-base catalyst triazobiciclodecene were compared with two metal-based catalysts, viz. scandium trifluoromethanesulfonate and dibutyl tin oxide. For the four catalytic systems, the efficiency and selectivity for the implementation of sorbitol were studied, mainly via 13 C and 31 P NMR spectroscopies, while side reactions such as ether formation and dehydration of sorbitol were evaluated via MALDI-ToF-MS. Especially the biocatalyst SPRIN liposorb CALB succeeded in incorporating sorbitol in a selective way without side reactions, leading to close-to-linear polyesters. By using a renewable hydroxylreactive curing agent based on L-lysine, transparent and glossy poly(ester urethane) networks were successfully synthesized offering a tangible example of bio-based coatings.