Dual ionically cross-linked hydrogels with ultra-tough, stable, and self-healing properties
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Excellent mechanical and self-healing features could make hydrogels an ideal candidate for the application of load-bearing soft tissue replacements such as cartilage. In this study, a dual ionically cross-linked 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC)/poly(acrylic acid) (PAAc)-Fe3+ hydrogel was constructed using a one-pot method (in situ polymerization of AAc in the presence of HACC and Fe3+). Both macromolecular positively charged HACC and Fe3+ metal ions acted as cross-linkers to form ionic bonds with negatively charged PAAc. The HACC/PAAc-Fe3+ hydrogels demonstrated ultra-high mechanical strengths (tensile strength of ca. 9.86 MPa and compressive stresses greater than 95 MPa at 99% strain), excellent self-recoverability (ca. over 90% toughness recovery within 5 h without any external stimuli), outstanding self-healing properties (ca. 74% self-healing efficiency at 70 °C for 48 h), transparency, and high stabilities in aqueous environments. The mechanical properties of the hydrogels could be adjusted by varying the concentration of HACC and Fe3+. This work provides a new approach for the construction of novel tough and transparent hydrogels with a fully ionically cross-linked network.
Mouse embryo fibroblasts
Attenuated total reflectance Fourier-transform infrared
Cell counting kit-8
Dulbecco’s modified eagle’s medium
Fetal bovine serum
2-Hydroxypropyltrimethyl ammonium chloride chitosan
Scanning electron microscope
This work was supported by the National Natural Science Foundation of China (No. 51173070), National Natural Science Foundation of Guangdong, China (No. 2016A030313097), and the Science and Technology Program of Guangzhou, China (No. 201707010264).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.