Synergistic Nanoconfinement and UV Crosslinking Enabling Self-Strengthening, Ultra-Robust Shape-Memory Elastomers

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Fatigue-induced degradation limits elastomer lifespan.
• Developing elastomers with enhanced mechanical properties and durability is crucial for reliable long-term service.

Purpose of the Study:

• To introduce a synergistic strategy for self-strengthening poly(urea-urethane) (PUU) elastomers.
• To enhance the mechanical properties and durability of PUU elastomers through nanoconfinement and stimuli-triggered cross-linking.

Main Methods:

• Coupling hydrazone-linked covalent organic framework (H-COF) nanoconfinement with UV-triggered cross-linking.
• Utilizing H-COF nanochannels to immobilize polymer chains and restrict mobility.
• Inducing radical polymerization of terminal C=C groups within nanochannels upon UV irradiation to form covalent cross-links.

Main Results:

• Achieved a 3.01× increase in tensile strength (85.1 MPa), a 2.10× enhancement in toughness (327.27 MJ•m⁻³), and a 2.20× improvement in fracture energy (303.65 kJ•m⁻²).
• Observed reduced domain spacing and homogenized morphology, with suppressed strain localization.
• Shortened shape-memory recovery time (up to 99.06%) and intensified fluorescence as an optical recovery signal.

Conclusions:

• The cooperative mechanism strengthens the elastomer network while preserving energy dissipation.
• Established a generalizable design principle for stimuli-programmed self-strengthening under nanoconfinement.
• Advanced elastomers toward adaptive durability with improved performance and functionality.