Main‐Side Chain Hydrogen Bonding‐Based Self‐Healable Polyurethane with Highly Stretchable, Excellent Mechanical Properties for Self‐Healing Acid–Base Resistant Coating

Abstract

Developing an autonomous self‐healing polyurethane (PU) elastomer with excellent mechanical properties and high ductility has attracted increasing attention. Nowadays, the synthesis of elastomers with excellent mechanical properties and rapid self‐healing at room temperature faces a huge challenge. Herein, This work reports a new supramolecular PU with excellent mechanical properties and rapid self‐healing at room temperature through the introduction of T‐type chain extender into the supramolecular polymer chain. The introduction of T‐chain extender can be used to enhance the mechanical strength of PU, and the multiple hydrogen bonds on the side‐chain provide theoretical support for the rapid self‐healing ability of PU. Maximum stress of the synthesized PU can reach 3.4 ± 0.15 Mpa, and maximum elongation at break can reach 3200% ± 160%. Due to flexibility and re‐constructability of side‐chain hydrogen bonds, PU stress repair efficiency can reach 96.7%, and can be self‐healing scratches rapidly and effectively at room temperature. The mechanical properties and self‐healing properties of PU can be adjusted by the content of T‐type chain extender. The PU is applied to the metal surface coating, which has excellent acid–base resistance, bond strength up to 2.9 ± 0.1 Mpa, and the ability to eliminate local damage on the coating surface quickly at room temperature.

Highly Adhesive and Tough Thermoplastic Polyurethanes Using a Furandicarboxamide Rigid Chain Extender with Noncovalent Interactions

“…The absorption peak of urethane CO appears at 1697 cm –1 . With the increase of chain extender amount, both the absorption peak for amide CO of the furandicarboxamide group at 1658 cm –1 and the stretching vibration absorption peak of −NH at 3300 cm –1 are enhanced, indicating the formation of more hydrogen bonds. , The CO peaks in the FT-IR spectrum within the wavenumber of 1600–1800 cm –1 were fitted using Gauss–Lorentz curves, as shown in Figure S6 in the Supporting Information. Both the contents of hydrogen bonding and ordered hydrogen bonding increase with the increase of chain extender amount, as indicated by Figure c.…”

“…After yielding, the molecular chains begin to move along the action of the external force. On the one hand, the weak hydrogen bonds between the molecular chains are partially dissociated so that the energy of the tensile strain is effectively dissipated; on the other hand, the multiple hydrogen bonds between the hard segments introduced by the chain extender can still exist as physical cross-linking points under large strain, and the material exhibits the features of an elastomer. ,,, As a result, the elongation at break and breaking strength of PUFD-0.5 are 2350% and 5.1 MPa, respectively. The tensile toughness of all samples is listed in Table S1 in the Supporting Information.…”

Recent advances in high-strength and high-toughness polyurethanes based on supramolecular interactions

“…Moreover, Xu et al successfully exploited PU elastomers with tunable mechanical and self-healing properties by incorporating a multi-hydrogen bonded T-type chain extender into the polymer chain. 98 The synthesized SPU coating material used on metal surfaces showed obvious acid–base resistance and could rapidly eliminate the local damage on the coating surface at room temperature due to its high bonding strength of 2.90 MPa; therefore, it not only had wide-ranging application prospects in metal surface coatings but also provided great guidance for the development of intelligent anti-corrosive coating materials. From these aforementioned examples, it can also be seen that self-healing after damage is considered to be the best strategy for developing high-performance organic coatings, and the exploitation of polymer coatings based on supramolecular chemistry is one of the most challenging and promising routes.…”

Rapid self-healing and tough polyurethane based on the synergy of multi-level hydrogen and disulfide bonds for healing propellant microcracks

“…The decomposition peak at about 420 1C represented the breaking of the soft polyurethane segment. 50,51 According to the details of Fig. 3a, PU-A was the first to undergo thermal decomposition compared with the other samples.…”