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Addressing the demand for integrating strength and durability reinforcement in shape memory polyurethane (SMPU) for diverse applications remains a significant challenge. Here a series of SMPUs with ultra‐high strength, self‐healing and recyclability, and excellent shape memory properties through introducing dynamic boron–urethane bonds are synthesized. The introducing of boric acid (BA) to polyurethane leading to the formation of dynamic covalent bonds (DCB) boron–urethane, that confer a robust cross‐linking structure on the SMPUs led to the formation of ordered stable hydrogen‐bonding network within the SMPUs. The flexible crosslinking with DCB represents a novel strategy for balancing the trade‐off between strength and durability, with their strengths reaching up to 82.2 MPa while also addressing the issue of durability in prolonged usage through the provision of self‐healing and recyclability. The self‐healing and recyclability of SMPU are demonstrated through rapid dynamic exchange reaction of boron–urethane bonds, systematically investigated by dynamic mechanical analysis (DMA). This study sheds light on the essential role of such PU with self‐healing and recyclability, contributing to the extension of the PU's service life. The findings of this work provide a general strategy for overcoming traditional trade‐offs in preparing SMPUs with both high strength and good durability. [ABSTRACT FROM AUTHOR]

Polyhydroxyurethanes (PHUs), which are synthesized through the aminolysis of cyclic carbonates, avoid the use of toxic isocyanates compared with traditional polyurethanes (PUs) and have aroused great interest. The large number of hydroxyl groups in the network endows PHUs with unique features, such as recyclable properties and fluorescent properties. To establish the high performance and multifunctionality of PHUs, we designed a molecular structure to fabricate PHUs with mechanical robustness, shape memory properties, fluorescent properties, and recyclable properties. The yielded PHU crosslinked by the quaternary thiol and weak but dense hydrogen bonds (H‐bonds) shows unprecedented high mechanical properties with a tensile Young's modulus of 3.13 GPa, comparable to that of polyimide, a tensile strength of 59.2 MPa at room temperature and an excellent toughness of 27.9 MJ/m3 at 50°C, and good damping properties (tanδ ≥ 0.3, temperature range of 35.2°C). Interestingly, fluorescence caused by the aggregation of carbamate within PHUs allows it to be applied for damage self‐reporting to visualize tiny cracks or magnify fractures. Furthermore, both the thermosetting PHUs and recycled thermosetting PHUs presented excellent shape memory performance. This study provides certain inspiration for the design and development of highly rigid multifunctional polymers. [ABSTRACT FROM AUTHOR]

A series of castor oil-based polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by two kinds of hydroxy-terminated liquid nitrile rubber (HTLN) was prepared. A systematic investigation of the tribological properties of the two kinds of HTLN-modified PU/EP IPN composites was carried out through a pin-on-disk arrangement under dry sliding conditions. Experimental results revealed that the incorporation of HTLN can improve the friction and wear properties of PU/EP IPN significantly. Both the friction coefficient and wear loss decreased with increasing content of HTLN. The worn surfaces of the samples were analyzed using scanning electron microscope and a three-dimensional (3D) noncontact surface-mapping profiler; the results showed that the worn surfaces of the PU/EP IPN composites became smooth when the HTLN was added. The mechanisms for the improvement of tribological properties are discussed. [ABSTRACT FROM PUBLISHER]

A series of polycaprolactone (PCL)-based polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer networks (IPNs) were prepared and their damping propertiesand thermal stability, as well as mechanical properties, were systematically studied in terms of composition and the values of the PU isocyanate index (R). The morphologies of the PU/EP IPNs were observed by scanning electron microscope (SEM) and atomic force microscope (AFM) characterization and the relationship between the morphologies and the properties is also discussed. The damping properties and thermal stability measurements revealed that the formation of PU/EP IPNs could significantly improve not only the damping properties but also the thermal stability. Meanwhile, the mechanical tests showed that the tensile strengths of the IPNs decreased, while their impact strengths increased with increasing PU content. The value of the PU isocyanate index also had significant impacts on the properties of the IPNs when the PU to EP ratio was fixed, which could be an effective means for manipulating the fabrication of PU/EP IPNs. From the results obtained, the PCL-based PU/EP IPNs hold promise for use in structural damping materials. [ABSTRACT FROM PUBLISHER]