Isocyanate-Free Route to Poly(carbohydrate–urethane) Thermosets and 100% Bio-Based Coatings Derived from Glycerol Feedstock

Abstract

Glycerol serves as the exclusive bio feedstock for the preparation of high purity sorbitol tricarbonate (STC) as new intermediate for poly(carbohydrate–urethane) thermosets and 100% bio-based non-isocyanate polyhydroxyurethane (NIPU) coatings. In this process, glycerol-based acrolein is dimerized, carbonated, and oxidized, thus producing the highly reactive diepoxy functional ethylene carbonate (DOC), which by facile chemical CO2 fixation yields high purity STC. Opposite to most state-of-the-art multifunctional five-membered cyclic carbonates and regardless of the feedstock used for its manufacture, STC enables amine curing at ambient temperature even in the absence of catalysts. According to FT-IR and NMR spectroscopic analyses of the amine/carbonate reaction kinetics, the internal cyclic carbonate group is 3 times more reactive with respect to the two terminal carbonate groups. This is attributed to the electron-withdrawing effect of terminal cyclic carbonates. Curing STC with a blend of bio-based flexi...