Room-Temperature Self-Healing Polyurea with High Puncture and Impact Resistances

Abstract

Polyureas are widely used as protective materials because they have good mechanical strength, toughness, and strainrate-dependent behavior. However, the fast reaction between −NCO and the −NH 2 component results in gelation in seconds, limiting their performance regulation and applications. In this study, we report a novel strategy to fabricate one-component polyurea with room-temperature self-healing, puncture resistance, and impact resistance. First, a latent curing agent was synthesized via the Schiff base reaction of an aliphatic diamine with isobutyraldehyde. Then, they were mixed directly with isocyanate. Such a mixture was uncured in storage without moisture, but it was cured once in contact with moisture in the application. So, it was called one-component polyurea. The polyurea exhibits roomtemperature self-healing properties with a healing efficiency of up to 98%. It has puncture displacement as high as 15.1 cm by sharp objects. The polyurea also exhibits excellent impact resistance and dissipative energy capacity because it possesses strain-ratedependent behavior. The polyurea can be integrated into Kevlar fabrics to form a flexible puncture-resistant composite and combined with carbon nanotubes to form flexible and wearable strain sensors. It is expected to find applications in intelligent soft materials, soft body armor, wearable flexible sensors, and other fields.

Self-Healing Elastomers with Unprecedented Ultrahigh Strength, Superhigh Fracture Energy, Excellent Puncture Resistance, and Durability Based on Supramolecule Interlocking Networks Formed by Interlaced Hydrogen Bonds

“…The high transparency and low haze were mainly based on the amorphous structure of PUU elastomers. 14,18 The amorphous dispersion peaks at about 2θ = 20°in the XRD curves of the PUU elastomers (Figure S3) proved the amorphous structure of the PUU elastomers.…”

“…The transparent elastomers with excellent mechanical properties, high transmittance, and good durability are widely applied in the field of transparent protective coatings, adhesives, actuators, soft robots, and flexible electronics. − Moreover, for prolonging the service lifespan of elastomers and reducing the waste of resources, the self-healing and reprocessing properties integrated into transparent elastomers with high mechanical properties and good durability are encouraged to be studied. − However, multiple different properties in elastomers are mutually exclusive based on the different and contradictory molecule chain structures. − For example, based on the locking effect on the polymer chains, covalent bonds and noncovalent bonds with high binding energy, rigidity groups, crystallization, and strong intermolecular interactions are the key factors to the high mechanical properties and good durability. − Oppositely, one of the necessary conditions for excellent self-healing properties is great molecular chain mobility, , and amorphous structure is the basis of the high transmittance and low haze . Therefore, it is still a huge challenge to synthesize transparent elastomers with high mechanical properties, excellent self-healing properties, and durability simultaneously.…”

“…11−15 For example, based on the locking effect on the polymer chains, covalent bonds and noncovalent bonds with high binding energy, rigidity groups, crystallization, and strong intermolecular interactions are the key factors to the high mechanical properties and good durability. 11−15 Oppositely, one of the necessary conditions for excellent self-healing properties is great molecular chain mobility, 17,18 and amorphous structure is the basis of the high transmittance and low haze. 19 Therefore, it is still a huge challenge to synthesize transparent elastomers with high mechanical properties, excellent self-healing properties, and durability simultaneously.…”

Synthesis of completely solvent-free biomedical waterborne polyurethane with excellent mechanical property retention and satisfactory water absorption

“…During the loading-unloading cycles for 30 min, the MWPU1.5 lm exhibited almost no permanent deformation and showed excellent resilience under water, while MWPU1.6 broke in the tenth cycle, possibly because it has a higher covalent crosslinking density and cannot dissipate energy effectively. 65,66 MWPU1.5 absorbs more water, and the plasticizing effect of water makes the loose cross-linked network more exible. The resilience can be increased, which is also retained in the scaffold.…”

Antifouling and Self-Healing Performance of Marine Coatings Based on Hydrogen-Bond Interactions

“…In these contexts, we report here a self-healing and antifouling marine coating based on PDMS-based PU. Different from other studies on hydrogen bonding mechanisms based on polyurea, 30 polyurethanes with more carbonyl groups were used in this work to construct a "cross-linking" network with alternately strong and weak bonds to achieve self-healing performance at room temperature. Its fabrication was carried out under mild and solvent-free conditions and has the potential to be applied in industrial production.…”