Synthesis of Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks. Part II: Self-healing, Reprocessing, and Degradation

keywords:lignin  non-isocyanate polyurethane  self-healing  reprocessing

Abstract:This study provides a comprehensive understanding of the polymeric properties of lignin-based non-isocyanate poly(imine-hydroxyurethane)s (LNIPUs). The properties of the LNIPUs are affected by changes in the stoichiometric feed ratios of the bis(6-membered cyclic carbonate) (BCC) and levulinate enzymatic hydrolysis lignin (LEHL). The results showed that the LNIPUs exhibited a short relaxation time and excellent thermal repair and degradation properties. With a change in the LEHL content in the LNIPUs to 45.53%, a relaxation time of only 9 s was achieved, and the thermal repair rate of the scratches reached 93%. Furthermore, the tensile strength of the LNIPUs decreased with an increase in the LEHL content after two hot-pressing processes, while a higher than 75% tensile strength was maintained after the second hot-pressing treatment. The LNIPUs exhibited thermoresponsive shape memory property with deformation and shape fixing at 80℃. In addition, the as-synthesized LNIPUs were soluble in ethylene glycol in the absence of any organic solvents. This work demonstrates the synthesis of LNIPUs with self-healing, reprocessing, shape memory, and degradation properties.