Self-healable polymer networks from bio-based platform chemicals through Passerini and Diels–Alder reactions: a preliminary study

It is urgent and important to design and prepare functional polymers utilizing biomass or bio-based platform chemicals due to fossil resource/energy crisis. We designed and synthesized two linear polymers LP 1 and LP 2 from bio-based platform chemical furfural as well as other biomass-derived feedstock adipic acid and 1,6-hexadiamine using efficient and 100% atom-economy Passerini three-component reaction. The number-average molecular weights of LP 1 and LP 2 are 2189 da and 5464 da, respectively. The products LP 1 and LP 2 were crosslinked with N,N ´-4,4´-diphenylmethyene bismaleimide (BMI) through Diels–Alder cycloaddition reactions to form the corresponding polymer networks CP 1 and CP 2 , respectively. Both CP 1 and CP 2 showed good chemical resistance to acid and ethyl acetate, but relatively poor resistance toward base and THF. Gel fraction values of CP 1 and CP 2 were 82% and 74%, respectively, indicating that most of the linear segments of LP 1 and/or LP 2 were crosslinked after Diels–Alder reactions. Thermal property analysis indicated that the two polymer networks were at rubbery state as their T g values were 14.78 and 7.00 °C, respectively. Td 10 values of CP 1 and CP 2 were 151 °C and 131 °C, respectively. The presence of dynamic D–A bonds caused both CP 1 and CP 2 to exhibit intrinsic self-healable performance at 60 °C or higher. Furthermore, CP 2 also showed rapid self-healing behavior (within 3 min) under UV (360 nm) irradiation due to the existence of dynamic disulfide bonds in the main chain. Graphical abstract