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To endow thermoset shape memory polymers with self-healing and recyclable functionalities is highly desirable. In this study, we fabricated Diels-Alder crosslinked polyurethane/functionalized reduced graphene oxide composites (DAPU-FRGOs) through in situ polymerization. The incorporated FRGO with urethane chains could achieve good compatibility with the DAPU matrix, forming physical and chemical crosslinking structures in the composite. And the most effective improvements of mechanical, thermal stability, crystallization-triggered, and photothermal effect were achieved for the DAPU/FRGO2 composite with 2 wt% FRGO. Owing to the outstanding crystallization-induced and photo-thermal effects of FRGO and the thermal reversible behavior of Diels-Alder bonds, the DAPU-FRGO2 composite showed rapid shape memory (<10 s, shape-fixity and recovery ratios were 92.3% and 94.1%, respectively) and self-healing (<120 s, healing efficiencies for tensile strength and elongation at break were 89.3% and 90.4%, respectively) under near-infrared light. Meanwhile, the DAPU-FRGO2 composite exhibited good repeatability of self-healing and shape-memory functionalities, and its shape memory parameters and healing efficiencies were maintained above 92% and 85% after three-cycles, respectively. Further recycling test demonstrated that the mechanical properties of the recycled DAPU-FRGO2 composite could be recovered to more than 82% of the original sample. This work provides a heuristic perspective for designing durable light-responsive thermoset shape memory composite materials. Image 1 • Dual-crosslinked DAPU-FRGOs composites were fabricated via in situ polymerization. • FRGO with urethane chains exhibited significantly enhanced compatibility with DAPU matrix. • Properties of composite were significantly enhanced with the introduction of 2 wt% of FRGO. • DAPU-FRGO2 composite showed excellent shape memory and self-healing under NIR light. • DAPU-FRGO2 composite exhibited good recyclability by NIR light and solution casting. [ABSTRACT FROM AUTHOR]

Herein, combining the visible light-induced dynamic diselenide bonds and pendant 2-ureido-4[ 1H ]-pyrimidinone (UPy) groups, a novel type of eco-friendly water-dispersed supramolecular polymers (DSe-WSPs) with excellent healing properties was developed. Transparent films obtained from DSe-WSPs emulsions demonstrated improved mechanical properties after the incorporation of UPy groups. Synergy effect of dynamic diselenide bonds and UPy groups was crucial for the fast healing process (10 minites) of DSe-WSPs polymers under visible light with a healing efficiency over 95.0%. Through this elaborated architecture, a fast room temperature self-healability and reprocessability could be achieved in super-tough polymers (69.10 MJ m−3) with eco-friendly feature, which has not been realized in the reported self-healing polymers. To our exiting, the DSe-WSPs polymer can be also used as a macro-initiator to initiate polymerization of vinyl monomer under visible light, which was firstly reported for self-healing polymers. These characteristics of fast room temperature self-healability, reprocessability, photo-initiated polymerization ability, and eco-friendly feature with robust mechanical properties present a feasible way to satisfy the demands of high performances and sustainability for the next-generation materials. Image 1 • Eco-friendly healable supramolecular polymers containing dynamic Se–Se were prepared. • Synergy effect of dynamic Se–Se and UPy groups was crucial for fast healing (10 min). • Fast self-healability and robust mechanical properties were achieved simultaneously. • Visible light is an easily manipulated way to achieve room-temperature self-healing. • Self-healing polymer was firstly used as a macro-initiator to initiate polymerization. [ABSTRACT FROM AUTHOR]

• A novel multifunctional hydrogel was prepared using a simple one-pot method. • The hydrogel possesses good mechanical property and self-healing ability. • The self-healing process is not significantly disturbed by external conditions. • The hydrogel is easy to recycle using pollution-free methods. Antibacterial hydrogels capable of self-healing when damaged have been developing rapidly in recent years owing to their promising applications in biomedical and relevant fields. Despite great achievements, the acute defects of low mechanical property, limited self-healing ability, potential cytotoxicity, poor recyclability and sophisticated preparation process hinder their further applications. Herein, a facile one-pot strategy is proposed to prepare the hydrogel with antibacterial and non-cytotoxic properties using aluminium(III) ions (Al3+s) and carboxymethyl chitosan nanoparticles (CMCS NPs) to crosslink with polyacrylic acid (PAA) chains through triple dynamic non-covalent interactions (coordination, hydrogen and electrostatic interactions). Benefit from the strong triple-crosslinked network and dynamic nature of non-covalent bonds, the PAA-Al3+-CMCS hydrogels exhibit a desirable mechanical property (fracture strength of 190.9 kPa, fracture elongation of 1930%) and self-healing ability (healing efficiency 92.9% of stress, 98.8% of strain, 25 °C, 24 h of healing) which is not obviously disturbed by surface ageing or erosion (e.g. acid, alkali and salt solutions). Besides, owing to the fully physical crosslinking structure, the as-prepared hydrogels are easy to recycle in pollution-free ways. This strategy opens a new avenue to fabricate hydrogels with outstanding mechanical properties and multi-functionality synchronously. [ABSTRACT FROM AUTHOR]

Abstract In this work, polyurethane/functionalized graphene oxide composites containing diselenide bonds were fabricated by covalently incorporating functionalized graphene oxide (FGO) into hydroxyl-terminated polyurethane prepolymers via in-situ polymerization. It was found that the isocyanate terminated molecules were covalently attached onto the graphene oxide surface, and the FGO could act as a multifunctional reinforcer in mechanical and photo-thermal properties of polyurethane composites. Significant enhancements of mechanical, thermal transport, and crystallization performances of composites were observed with the incorporation of 2 wt% of FGO. Due to the photo-thermal and crystallization-induced effects of FGO as well as the exchangeable characteristic of diselenide bonds, the PID-FGO2 composite exhibited both shape memory and repeatable self-healing functions upon exposure to near infrared (NIR) irradiation. In particular, the introduction of diselenide bonds could greatly improve the healing efficiency from ∼45% to ∼90%, and the healing efficiencies were maintained above 75% even after five healing cycles. Such favorable healing is acquired by the photo-thermal response, shape memory effect, and diselenide exchange reaction simultaneously, and the shape memory effect is of great importance for assisting the healing process. We expect that this work could provide a viable avenue for multifunctional composite materials. Graphical abstract Image 1 Highlights • Polyurethane/functionalized graphene oxide (FGO) composites containing diselenide bonds were fabricated. • Properties of composites were significantly enhanced with the incorporation of 2 wt% of FGO. • PID-FGO2 composite exhibited both shape memory and repeatable self-healing functions under near infrared light. • Self-healing behavior was achieved by the photo-thermal, shape memory effect, and diselenide metathesis simultaneously. • Further addition of diselenide bonds could effectively strengthen the healing efficiency. [ABSTRACT FROM AUTHOR]

It is still a great challenge to synthesize waterborne polyurethane (WPU) with excellent mechanical performance and fast room-temperature self-healing ability because of the mutually exclusive nature of these properties. Herein, a room-temperature self-healing waterborne polyurethane based on Zn2+-carboxyl coordination bond and hydrogen bond was prepared by adding zinc ion buffer solution to WPU emulsion. Due to the synergistic effect of dynamic coordination bonds and hydrogen bonds, the optimized sample (WPU-Zn-3) exhibited excellent mechanical properties (a tensile strength of 7.26 MPa, a elongation at break of 855 % and an exceptional toughness of 26.76 MJ/m3) and fast room-temperature self-healing capacity under ethanol induction (a high healing efficiency of 88 % within 4 h), showing a good balance between fast room temperature healing ability and excellent mechanical properties. Interestingly, this method also works for nickel ions but not for iron and aluminum ions. Furthermore, compared with zinc chloride and zinc nitrate, the waterborne polyurethane containing zinc acetate showed the best comprehensive performance. Due to the presence of zinc ions, the sterilization rates of WPU-Zn-3 film samples against Escherichia coli and Staphylococcus were 97.1 % and 97.8 %, respectively. Specially, we introduced graphene quantum dots into the waterborne polyurethanes to construct photoluminescence films and demonstrated their potential applications prospect in the fields of information encryption and anti-counterfeiting. This work broadens the avenue for fabricating room-temperature self-healing and multifunctional waterborne polyurethanes. [Display omitted] • A facile strategy to fabricate room-temperature healing WPU with coordination bond. • With this strategy, fast healing and robust mechanical properties are achieved simultaneously. • This strategy does not work for iron and aluminum ions, but for nickel and zinc ions. • The as-prepared WPU film exhibits excellent antibacterial properties. • WPU-Zn/GQDs composite film displays photoluminescence, information encryption and anti-counterfeiting. [ABSTRACT FROM AUTHOR]