Self-healing polymers with tunable mechanical strengths via combined hydrogen bonding and zinc-imidazole interactions

Abstract The development of self-healing polymers with tunable mechanical performances is an enormous challenge. Herein, self-healing polymers with tunable mechanical strengths via combined hydrogen bonding and Zn(II)-imidazole interactions were successfully synthesized. This synthesis was accomplished by introducing urea hydrogen bonding and Zn(II)-imidazole interactions into self-healing polymers polymerized from a new bifunctional monomer of 2-(3-(3-imidazolylpropyl)ureido)ethyl acrylate (IUA). The dual dynamic effects of urea hydrogen bonding and Zn(II)-imidazole interactions can simultaneously endow polymers with better self-healing capacities and mechanical properties. The synthesized polymers with urea hydrogen bonding and Zn(II)-imidazole interactions motifs exhibited over 90% self-healing efficiency under mild conditions. The mechanical strengths of the polymers can be flexibly tuned from 35.0 kPa to 4.41 MPa by varying the molar ratio of imidazole/Zn(II). When the polymers are damaged, the urea hydrogen bonds and Zn(II)-imidazole coordination can contribute to the reconstruction of the broken polymer networks and thus provide self-healing abilities. The interactions of hydrogen bonding and Zn(II)-imidazole coordination were confirmed by in-situ FT-IR spectra of the self-healing polymers at different temperatures.