Title : Functionalization of lignin-derived monomers for polyurethane production
Abstract:
Lignin, a waste product in the pulp and paper processing of cellulosic fibers, is comprised of a partial aromatic structure which can also be depolymerized into phenolic by-products as monomer precursors for further functionalization and polymerization. The main objective of our research is to make sustainable materials from these lignin-derived monomers, particularly polyurethanes as they are some of the most prevalent polymers that can be made from biobased materials. This work is divided into 3 research foci: in the first part, a series of high molecular weight polyurethanes and polyesters were synthesized from diols derived from lignin phenolics containing the aldehyde functionality. Additional work involved the preparation of polyester polyols from one of these diols at concentrations of 10 wt% and 25 wt% to be used in polyurethane foams. The two polyols prepared from this diol were shown to have higher acid values and hydroxyl numbers than the control polyols, while the foams prepared from the 10 wt% polyol were found to have similar or lower mechanical properties compared to the control foams. The second part involved a one-step synthesis of organic diols from several lignin phenolics to prepare thermoplastic polyurethanes. The diols were synthesized in moderate to high yields, while the polyurethanes revealed different degrees of rigidity or flexibility depending on the diisocyanate source. The last part utilized lignin-derived bisphenols for the synthesis of polyurethanes and non-isocyanate-based polyurethanes. Two bisphenols were prepared from 4-propylguaiacol and eugenol and converted into diols in one step for polyurethane synthesis or cyclic carbonates in two steps for non-isocyanate polyurethane synthesis.
