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

Abstract

The preparation of luminescent self-healing materials simultaneously feature superior integrated mechanical properties is still a great challenge because the relationship between the self-healing ability and mechanical capacities of a material...

Cu2+-Induced “Off–On–Off” Switching Luminescence of Cellulose-Based Luminescent Hydrogels

“…Upon excitation at 282 nm, the emission spectra of Eu 3+ -CLHs in Figure 3A exhibited four sharp peaks at 595, 616, 650, and 695 nm, attributed to the 5 D 0 → 7 F J (J = 1, 2, 3, and 4) transitions of Eu 3+ with the peak at 616 nm as the prominent feature, which is primarily responsible for the red emission color. 38,39 It is worth noting that the 5 D 0 → 7 F 2 transition is a classical electric dipole transition and is fairly sensitive to the localized symmetry of Eu 3+ . At the same excitation wavelength, emission spectra of Tb 3+ -CLHs in Figure 3B show four sharp lines attributed to the 5 D 4 → 7 F J (J = 6−3) transitions at 492, 544, 583, and 622 nm, respectively.…”

Stimuli-Responsive Self-Healing Luminescent Materials Based on Lanthanide Ions and Bipyridine Moieties

“…33,35,36 Although the mechanical properties of PU-HMDI-Ln are marginally inferior to those of Ln-Tpy-PPG and HPU-TPy 0.25 -Ln because the groups coordinating with Ln 3+ are situated at the end group position, reducing the steric hindrance of the coordinating groups on the polymer chains coordinating with Ln 3+ , the mechanical properties of PU-HMDI-Ln are adequate for most practical applications. 31,32 In addition to mechanical properties, three elastomers (PU-HMDI-Tb, PU-IPDI-Tb, and PU-HDI-Tb) were severed into two sections and healed for 12 h at ambient temperature to evaluate their healing abilities (Figures 2A and S8). Two sections of PU-HMDI-Tb were reconnected and could withstand their weight, whereas the fracture surfaces of PU-IPDI-Tb and PU-HDI-Tb were not fully healed, indicating superior self-healing behavior of PU-HMDI-Tb compared to PU-IPDI-Tb and PU-HDI-Tb.…”

“…These polymers exhibit high luminescence characteristics typical of lanthanide complexes, resulting from energy transfer from ligands to Ln 3+ , and promising mechanical strength alongside remarkable self-healing abilities due to the reversibility of the coordination bonds and H-bonds within these systems. 31,32 Furthermore, stimulus-responsive luminescence has been simultaneously achieved in certain instances. 33,34 In addition, the luminescence, self-healing, mechanical properties, and stimulus-responsiveness of these polymers can be conveniently modulated by altering the ligand moieties capable of coordinating with Ln 3+ and the structure of the polymer chain to which the ligands are tethered.…”

“…Luminescent metallo-supramolecular polymers derived from the coordination between ditopic ligands and lanthanide ions (Ln 3+ ) have been reported to exhibit superior self-healing behavior. − Unfortunately, their mechanical strength is insufficient for processing into self-standing films, which hinders their practical implementation in self-healing light-converting films. − The combination of dense coordination bonds and hydrogen bonds (H-bonds) within the polymer chain can endow the final products with intriguing self-healing properties and satisfactory mechanical strength. − Transition metal ions such as Zn 2+ , Cu 2+ , and Fe 3+ are commonly employed to coordinate with ligands attached to polymer chains, forming robust self-healing polymers. − Motivated by this concept, our group recently reported luminescent polymers through the coordination bonds between Ln 3+ and polymer ligands containing terpyridine as well as H-bonds among the polymer chains. These polymers exhibit high luminescence characteristics typical of lanthanide complexes, resulting from energy transfer from ligands to Ln 3+ , and promising mechanical strength alongside remarkable self-healing abilities due to the reversibility of the coordination bonds and H-bonds within these systems. , Furthermore, stimulus-responsive luminescence has been simultaneously achieved in certain instances. , In addition, the luminescence, self-healing, mechanical properties, and stimulus-responsiveness of these polymers can be conveniently modulated by altering the ligand moieties capable of coordinating with Ln 3+ and the structure of the polymer chain to which the ligands are tethered. , However, most luminescent polymers tend to lose their exceptional mechanical properties under high humidity as polymers with polar groups can absorb water and become easily plasticized. − Moreover, the transmittance of such polymers significantly decreases due to the presence of absorbed water, impeding their application in optical and display devices . Recently, Fujisawa et al reported a poly (ether thiourea) containing only 10 mol% of 4,4′-dicyclohexylmethane diisocyanate (HMDI), which exhibits mechanical robustness and can self-heal at ambient temperatures .…”

Fully Closed-Loop Recyclable Thermosetting Polythiourethane Microspheres and Their Application in Efficient Fabrication of Composites with Segregated Structures

“…CANs rely on dynamic covalent bonds that can break/reform and recombine either autonomously or with appropriate stimuli (esp. light , and heat − ), endowing polymers with unprecedented properties, such as self-healing, ,, recyclability, , weldability, and reprocessabIlity. − So far, many dynamic covalent bonds, such as Diels–Alder, , transesterification, , carbamate bonds, thiol–ene click reactions, disulfide bonds, − thiocarbamate bonds, − thiol–anhydride, transimination, boronic esters, , siloxane exchange, and hindered urea bonds, have been applied to design the thermosetting polymers with various types of CANs. , …”