Designing self-healing materials with multiresponsive self-healing and high mechanical performance has promising applications in wearable electronics and soft robots. In this study, polydopamine (PDA) particles and hindered urea bonds are used as functional nanofillers and dynamic motifs, respectively, in the production of dynamic cross-linked polyurea/PDA (DCPU/PDA) nanocomposites via facile in situ photoinitiated copolymerization. PDA particles form good interfacial bonds with the DCPU matrix, which endows the nanocomposites with enhanced thermomechanical and remotely photoresponsive self-healing properties as well as excellent photothermal effects. DCPU/PDA nanocomposites have higher toughness (∼14.96 ± 2 MJ m −3 ) and stretchability (up to 334 ± 20%) than pure DCPU. When damaged, they self-heal rapidly and effectively in response to near-infrared light. The fast responsive self-healing ability is enabled by the excellent photothermal effect of PDA and the dynamic exchange reaction of the hindered urea bonds. In addition, DCPU/PDA nanocomposites are malleable and easily recyclable. Finally, their outstanding photoactuation makes them suitable for applications as soft actuators in wearable electronics and soft robots.
Designing a crosslinked polymer with self-healing, recyclable, and mechanical properties is a significant challenge in the field of self-healing chemistry. Herein, robust, intrinsically self-healing, crosslinked polyureas (C-PUs) are prepared via a facile one-pot photo-induced copolymerization to address the aforementioned limitation. The key strategy involves the introduction of a synthetic monomer with reversible urea bonds into the polymer network as a versatile dynamic crosslinker. The resultant C-PUs are a class of resource-saving materials with a combination of excellent intrinsic self-healing capability with outstanding mechanical robustness. Notably, the properties of the materials can be easily tuned by simply adjusting the dynamic crosslinker content. In addition, an environmentally friendly polymer reprocessing is achieved and the potential of the materials in the smart anticorrosion application is investigated. These desirable properties are attributed to the underlying topological network rearrangement enabled by the dynamic urea bond exchange reaction, which is confirmed by stress relaxation tests. Therefore, the resulting self-healing C-PUs can serve as models to extend the scope of applications in smart protective materials or ocean engineering.
Polymer networks crosslinked by reversible noncovalent crosslinks have been applied in self‐healing and recyclable sustainable materials but result in limited mechanical strength. Herein, a crosslinked polymer blend that is based on a urethane–arcylate system with a combination of reversibly noncovalent intrachain and interchain hydrogen bonds and dynamically covalent urea bonds is developed through facile in situ photo‐induced copolymerization. An essential step is the introduction of a flexibly dynamic crosslinker bearing robustly hindered urea bonds and urethane–urea structures into the network, which endows the dynamic network with a synergy of mechanical robustness and desirable self‐healing ability. The dynamic networks exhibit rapid self‐healing at mild conditions (70 °C, 30 min), extreme toughness (≈34.76 MJ m−3), high tensile strength (≈7.78 MPa), superior stretchability (≈932%), long‐term stability, recyclability, and weldability. More importantly, the mechanical and self‐healing properties of the resultant materials can be fine‐tuned by adjusting the dynamic crosslinker content. These superior properties are attributed to the dynamic reversibility of hydrogen bonds and urea bonds as monitored by rheological tests. The extremely facile fabrication approach and superior properties of the resulting self‐healing polymers can find applications in sustainable smart materials and self‐healing conductive sensors.
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