Li Ting,Zheng Tian-Ze,Guo Zhao-Xia,Xu Jun,Guo Bao-Hua
A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1 H ]-pyrimidone (UPy) units is innovatively designed to prepare polyureas with high overall mechanical properties. Three polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate (IPDI) with a UPy-derived diisocyanate. The formation of quadruple hydrogen bonds in hard segments via UPy dimers was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the polyureas were evaluated by uniaxial tensile testing. Compared to the polyurea without UPy units, remarkable improvements in Young’s modulus, tensile strength, and toughness were simultaneously achieved when UPy units were incorporated. The mechanism behind the strong strengthening effect rooted in the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds, which were stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups, and the slower soft segmental dynamics reaveled by both increased T g and relaxation time of the soft segments. The mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds that served as stronger sacrificial bonds upon deformation. This work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.
The development of hydrogels possessing both excellent self-healing and mechanical properties in hydrogel science due to their tight relationship with the many potential application scopes is of great significance. Herein, a novel class of polyurethane (PU) hydrogels with intermolecular quadruple hydrogen-bonding interactions were designed and fabricated by the copolymerization of poly(ethylene glycol) methacrylate end-capped urethane ether prepolymer (PU-PEGMA) with 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (SCMHBMA) bearing the 2-ureido-4-pyrimidone (UPy) unit. The effects of the SCMHBMA content on the self-healing behaviors and mechanical properties of the PU hydrogels were investigated. The results indicate that the fabricated PU hydrogels can autonomously and rapidly repair occurring incisions or cracks at ambient temperature without the need for any stimulus and possess high deformability under both tensile and compressive stress and strong recoverability upon removal of stress, thus exhibiting outstanding self-healing, elasticity, robustness and toughness. The presence of UPy units in PU macromolecular chains is a decisive factor endowing the PU hydrogels with these characteristics.
Corrosion remains a critical challenge, particularly in aqueous environments, where traditional coatings struggle to maintain integrity. Despite advancements, self-healing materials often exhibit insufficient healing efficiency and stability underwater. This work presents a novel PDMS-based self-healing elastomer, PDMS-SS 1 /UPy 1 , incorporating dynamic disulfide bonds and 2-ureido-4[1H]-pyrimidone (UPy) unit for robust amphibious self-healing. Synthesized via a two-step reaction, PDMS-SS 1 /UPy 1 exhibits high thermal stability (T 5 % = 362 °C), excellent mechanical properties, and >92 % self-healing efficiency at 90 °C. FTIR, Raman, and XPS confirm successful SS/UPy incorporation, while SEM and AFM reveal uniform morphology. Contact angle measurements and adhesion tests confirm environmental stability and substrate compatibility. Furthermore, EIS demonstrates exceptional corrosion resistance (>10⁸ Ω·cm² in NaCl solution), and the innovative application of distribution of relaxation times (DRT) analysis provides deeper insights into the coating's electrochemical behavior. PDMS-SS 1 /UPy 1 offers a promising solution for durable anti-corrosion protection in demanding aqueous environments.
危险品化学品经营许可证（带存储）