One-pot synthesis of thermally reversible materials using maleimide-polysaccharide and furan-lignin derivatives.

The bio-based materials potato starch (St) and Kraft lignin (KL) were chemically modified to create a thermally responsive network through a reversible Diels-Alder (DA) reaction between maleimide and furan groups present in St and KL, respectively. To achieve this, St was esterified in a one-pot synthesis at room temperature with 6-maleimidohexanoic acid (6-MHA) to produce St 6MHA aligning with the 12 principles of green chemistry, which was confirmed by FTIR, H, C, and 2D NMR spectroscopy. Furan (Fu) groups were introduced to KL by reacting furfuryl glycidyl ether with the phenol entities of KL, forming KL-Fu. The structures of the KL-Fu derivatives were characterized using FTIR, H, C, and P spectroscopy, as well as TGA. St 6-MHA and KL-Fu were then subjected to thermal cycloaddition through the DA reaction. Furthermore, controlled retro-DA reactions were induced thermally and confirmed by FTIR and H NMR spectroscopy. DSC analysis of the final products revealed the thermally responsive nature of the system. This study highlights the significant potential of such a thermally responsive system, demonstrating that effective chemical modification of abundant renewable feedstock can enable the development of high-value materials thereof.