Insertion of Urea Moieties for One‐Component Strong yet Tough, Self‐Healing Polyurea Protective Materials

Abstract

Polyurea has gained increasing attention in civil engineering, flexible electronics, and other emerging fields. However, owing to the rapid polymerization, tailoring their mechanical properties of polyurea for different applications remains challenging. Herein, a novel strategy is proposed for the insertion of urea moieties to prepare one‐component robust, mechanically tunable, and healable polyurea. First, the prepared latent curing agent, isophorone diisocyanate (IPDI), and NCO‐terminated prepolymer (PPGTD) are mixed. Due to the large difference in the reactivity of the ─NCO groups in IPDI and PPGTD, IPDI first reacts with the deblocked amino groups to form continuous urea moieties. The resulting urea moieties are inserted into the polyurea. This strategy provides a tremendous improvement in strength (500% increase), storage modulus (532% increase), and toughness (281% increase). Additionally, the as‐prepared polyurea exhibits excellent self‐healing, impact resistance, high transparency (>90%), and high dielectric constant (≈4.5). Thus, it can be used as a protective film and flexible substrate for electronic devices. Furthermore, the polyurea exhibits good versatility, which can be laminated with alumina ceramic sheets to form impact composites. This work opens up a promising avenue for the design and fabrication of polyurea material for flexible electronics and provides new insights into engineering anti‐impact materials.

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 PUU–OD–AD-1 elastomer, with an extremely low weight of only 0.04 g, can easily lift a 5 kg dumbbell, which is 125,000 times its weight (Figure b), when the mass of PUU–OD–AD-1, a 20 kg dumbbell, was easily lifted by stretched PUU–OD–AD-1 (Movie S1), demonstrating the extraordinary mechanical property of PUU–OD–AD-1. Meanwhile, by comparing different elastomers and some plastics reported by some literature (Figure c), ,,,− ,,,,− the PUU elastomers in this work exhibited ultrahigh mechanical properties. Except comparing with the PI–PUU composite elastomer, the PUU elastomers of our work exhibited the highest tensile strength in the field of pure PUU or PU elastomers.…”

“…The generality of these research strategies is based on multiple hydrogen bonds or supramolecular interactions formed by hydrogen bonds. Moreover, the quadruple hydrogen bonds with high binding energy at room temperature and dynamic at high temperature are the key factors to the above strategies to increase the mechanical property and introduce the self-healing property in elastomers. ,− However, the quadruple hydrogen bonds in these strategies are all composed of two of the same molecule units with hydrogen bond donors and recipients. Based on the same length and steric hindrance of the two same molecule units, the binding energy and the bonding stability of quadruple hydrogen bonds are limited due to strong repulsive secondary interactions, restricting the mechanical strength of the elastomer further increased. − …”

High-Performance Polyurea Improved by Reactive Nanocluster for Antibiofouling

“…To slow it down, the reaction was usually carried out with a large amount of polar solvent at a low temperature. 32,33 On the other hand, secondary amines, such as polyaspartic ester (PAE), have been used to reduce the reaction rate through steric hindrance and electron-induced effects. 34−36 While PAE-based polyurea can achieve adjustable gel times and good adhesion, the weaker hydrogen bonds formed by secondary amines result in relatively low tensile strength (<10 MPa).…”

“…Such a quick reaction prevents polyurea from sufficient wetting on the substrate, resulting in poor adhesion. To slow it down, the reaction was usually carried out with a large amount of polar solvent at a low temperature. , On the other hand, secondary amines, such as polyaspartic ester (PAE), have been used to reduce the reaction rate through steric hindrance and electron-induced effects. − While PAE-based polyurea can achieve adjustable gel times and good adhesion, the weaker hydrogen bonds formed by secondary amines result in relatively low tensile strength (<10 MPa). , To improve the tensile strength, the content of hard segments in polyurea was increased, but this usually made polyurea to be more brittle. Alternatively, nanofillers were added to improve the strength.…”

Intelligent anti-impact elastomers by precisely tailoring the topology of modular polymer networks

“…17,18 Specifically, polyurea can be applied to fields requiring extreme protection as it surpasses polyurethane in terms of chemical stability and mechanical attributes because of the high-density hydrogen bonds introduced by urea moieties. 19 For instance, polyurea synthesized through flexible–rigid supramolecular segment interactions or multiple hydrogen-bond stacking exhibits increased fracture strength, toughness, and stretchability, presenting considerable potential in anti-impact applications. 20,21 However, the expedited polymerization rate of polyurea imposes challenges on customizing its mechanical properties to fulfill anti-impact requirements.…”