Thermodynamically stable whilst kinetically labile coordination bonds lead to strong and tough self-healing polymers

• Published in: Nature communications Vol. 10; no. 1; p. 1164
• Main Authors: Lai, Jian-Cheng, Jia, Xiao-Yong, Wang, Da-Peng, Deng, Yi-Bing, Zheng, Peng, Li, Cheng-Hui, Zuo, Jing-Lin, Bao, Zhenan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 11.03.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/455; 639/638/911; Bond strength; Bonding strength; Chemical synthesis; Chlorophenol; Coordination compounds; Energy absorption; Humanities and Social Sciences; Mechanical properties; multidisciplinary; Polydimethylsiloxane; Polymers; Science; Science (multidisciplinary); Self healing materials; Silicone resins; Toughness; Zinc
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09130-z

There is often a trade-off between mechanical properties (modulus and toughness) and dynamic self-healing. Here we report the design and synthesis of a polymer containing thermodynamically stable whilst kinetically labile coordination complex to address this conundrum. The Zn-Hbimcp (Hbimcp = 2,6-bis((imino)methyl)-4-chlorophenol) coordination bond used in this work has a relatively large association constant (2.2 × 10 11 ) but also undergoes fast and reversible intra- and inter-molecular ligand exchange processes. The as-prepared Zn(Hbimcp) 2 -PDMS polymer is highly stretchable (up to 2400% strain) with a high toughness of 29.3 MJ m −3 , and can autonomously self-heal at room temperature. Control experiments showed that the optimal combination of its bond strength and bond dynamics is responsible for the material’s mechanical toughness and self-healing property. This molecular design concept points out a promising direction for the preparation of self-healing polymers with excellent mechanical properties. We further show this type of polymer can be potentially used as energy absorbing material. There is often a trade-off between mechanical properties (modulus and toughness) and dynamic self-healing in materials. Here the authors design and synthesize a polymer containing thermodynamically stable whilst kinetically labile coordination complexes to address this conundrum.