The Preparation of Lignin-Derivable Bisphenols for the Synthesis of Polyurethanes and Nonisocyanate Polyurethanes

The synthesis of lignin-derivable bisphenols for polyurethane (PU) and nonisocyanate polyurethane (NIPU) formation is herein investigated. Three bisphenols were synthesized from 4-propylguaiacol, eugenol, and syringol followed by the synthesis of three diols using ethylene carbonate (EC) and two cyclic carbonates using glycerol carbonate (GC) and dimethyl carbonate (DMC). The 4-propylguaiacol- and eugenol-derived diols and cyclic carbonates were explored independently for PU and NIPU syntheses, wherein it was observed that all PUs and NIPUs were amorphous. The PUs revealed higher thermal stabilities with the use of a rigid diisocyanate, while slightly higher thermal stabilities were observed for the NIPUs with the use of a nonbiobased aliphatic diamine. High molecular weights and dispersities (Đ’s) were observed for the soluble PUs, while the NIPUs had lower molecular weights and Đ’s when a biobased diamine was used.