A lignin/castor oil-based polyamide autonomous self-healing composite materials

Reconciling high toughness and autonomous self-healing ability at a low cost remains a formidable challenge in the development of bio-based self-healing elastomers. Herein, lignin was incorporated into castor oil-based polyamide (PBUDA) as a rigid filler and hydrogen bond donor through solution method. The lignin was uniformly dispersed in PBUDA, forming a phase separation structure that significantly improved the mechanical properties of polyamide materials. The mechanical strength of blends coating 40 % (wt%) lignin was 22.7 ± 1.84 MPa, which was five times higher than that of pure PBUDA. Meanwhile the toughness and Young's modulus were also increased by four times and fourteen times, respectively. Moreover, the activate dynamic hydrogen bond and low glass transition temperature (T_g) endowed the PBUDA-lignin blends excellent self-healing ability at room temperature. This study not only provides a viable pathway for the valorization of high-added lignin, but also facilitates the advancement of self-healing castor oil-based polyamides, thereby contributing to the promotion of sustainable materials.