Tough Double Metal-ion Cross-linked Elastomers with Temperature-adaptable Self-healing and Luminescence Properties

Stretchable Self-Healing Plastic Polyurethane with Super-High Modulus by Local Phase-Lock Strategy

In this work, a multiblock polyurethane (PU-Im) consisting of polyether and polyurethane segments with imidazole dangling groups is demonstrated, which can further coordinate with Ni²⁺ . By controlling the ligand content and metal-ligand stoichiometry ratio, PU-Im-Ni complex with vastly different mechanical behavior can be obtained. The elastomer PU-2Im-Ni has extraordinary mechanical strength (61MPa) and excellent toughness (420 MJ m^-3 ), but the plastic PU-4Im-Ni exhibits super-high modulus (515 MPa), strength (63 MPa), and good stretchability (≈800%). The metal-ligand interaction between polyurethane segments and Ni²⁺ is proved by Raman spectra, dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The polyurethane segments domain formed by microphase separation is dynamically "locked" by Ni²⁺ coordinated with imidazole, revealing a local phase-lock effect. The phase-locking hard domains reinforce the PU-Im-Ni complex and maintain stimuli-responsive self-healing ability, while the free polyether segments provide stretchability. Primarily, the water environment with plasticization effect serves as an effective and eco-friendly self-healing approach for PU-Im-Ni plastic. With the excellent mechanical performance, thermal/aquatic self-healing ability, and unique damping properties, the PU-Im-Ni complexes show potential applications in self-healing engineering plastic and cushion protection fields.

Unprecedented toughness in transparent, luminescent, self-healing polymers enabled via hierarchical rigid domain design

The preparation of luminescent self-healing materials simultaneously featuring superior integrated mechanical properties is still a great challenge because the relationship between self-healing ability and mechanical capacities is conflicted. Here, transparent luminescent materials with balanced self-healing behavior, extreme toughness, and fast elastic recovery are prepared via hierarchical rigid domain design by coordinating lanthanide (Ln³⁺) to terpyridine (TPy) moieties linked to the polymer chains formed through polymerization of tolylene-2,4-diisocyanate-terminated polypropylene glycol (PPG-NCO) and 1,6-hexanediamine (HDA). The hierarchical rigid domain containing lanthanide-terpyridine (Ln³⁺-TPy) coordination interactions and H-bonds formed by urea and urethane leads to a tough network that features unprecedented toughness of 133.35 MJ m^-3, which reaches 83% of that of typical spider silk (≈ 160 MJ m^-3) and is also dynamic for fast self-healing at ambient temperature. Besides, the multi-color emission, ranging from red through orange and yellow to green, can be achieved via adjusting the molar ratio of Eu³⁺/Tb³⁺. We believe that the strategy applied in this work provides some insights for the preparation of high mechanical strength luminescence materials with self-healing properties.

Advances and Challenges of Self-Healing Elastomers: A Mini Review

In the last few decades, self-healing polymeric materials have been widely investigated because they can heal the damages spontaneously and thereby prolong their service lifetime. Many ingenious synthetic procedures have been developed for fabricating self-healing polymers with high performance. This mini review provides an impressive summary of the self-healing polymers with fast self-healing speed, which exhibits an irreplaceable role in many intriguing applications, such as flexible electronics. After a brief introduction to the development of self-healing polymers, we divide the development of self-healing polymers into five stages through the perspective of their research priorities at different periods. Subsequently, we elaborated the underlying healing mechanism of polymers, including the self-healing origins, the influencing factors, and direct evidence of healing at nanoscopic level. Following this, recent advance in realizing the fast self-healing speed of polymers through physical and chemical approaches is extensively overviewed. In particular, the methodology for balancing the mechanical strength and healing ability in fast self-healing elastomers is summarized. We hope that it could afford useful information for research people in promoting the further technical development of new strategies and technologies to prepare the high performance self-healing elastomers for advanced applications.