Mechanically Robust and Self-Healable Polyureas Based on Multiple Dynamic Bonds

Abstract

The synthesis of polymeric materials that simultaneously possess multiple outstanding mechanical properties and self-healability is always a great challenge. Herein, we report the synthesis of a robust and self-healing polyurea material, which contains a dual metal coordination structure of Zn(II)-urea and Zn(II)-diamidepyridine as well as dense hydrogen bonds. Due to the synergistic enhancement of dynamic coordination bonds and hydrogen bonds in the supramolecular network, the obtained polyurea materials possess a combination of excellent mechanical properties and high-efficiency self-healing properties, which are adjustable by varying the content of Zn(II) ions. The optimal PU-L/Zn-3 sample has a tensile strength of ∼22.82 MPa, while the elongation at break is ∼1312% and the toughness is ∼222.68 MJ/m 3 . In addition, the fully cut sample exhibits a high healing efficiency of 95.7% based on toughness after treatment at 50 °C for 4 h. Multi-dynamic cross-linked polymers might provide a new way to obtain robust self-healing materials for protection materials and wearable electronics.

State-of-the-Art Polyurea Coatings: Synthesis Aspects, Structure–Properties Relationship, and Nanocomposites for Ballistic Protection Applications

“…This network can then undergo repetitive breaking and reformation, allowing multiple healing/repairing events. For dynamic covalent self-healing, covalent bonds such as disulfide bonds, Diels–Alder reactions, and imine bonds are used [ 114 , 115 ]. Dynamic chemical crosslinks based on exchangeable disulfide bonds were produced by reacting diamine chain extenders containing disulfide bonds with di- or triisocyanates [ 116 , 117 ].…”

High‐performance crosslinked polyurethane with fatigue resistance, anti‐wear for sealing

“…Wang et al integrate the superb mechanical strength and toughness, and healable properties of poly(urethane‐urea) elastomer by implanting a large number of irregularly arranged urea hydrogen bonds into hard domains 22 . In addition, toughening and strengthening can be simultaneously realized by using the dissipated energy of the sacrificial bond 23,24 . Besides, PU with self‐recoverable and self‐healing properties allows it to achieve an unparalleled performance through renewing the material under mild conditions to significantly improve the service life of PU, which also attracts broad attention 25–27 .…”

“…22 In addition, toughening and strengthening can be simultaneously realized by using the dissipated energy of the sacrificial bond. 23,24 Besides, PU with self-recoverable and self-healing properties allows it to achieve an unparalleled performance through renewing the material under mild conditions to significantly improve the service life of PU, which also attracts broad attention. [25][26][27] In addition to mechanical properties, wear resistance is another important indicator of PU elastomers as sealing materials.…”