Self-healing Polyurethane Research Articles

Mechanically robust, self-healing and stretchable electromagnetic shielding materials based on multi-component dynamic bonded polyurethane elastomer

Stretchable self-healing electromagnetic interference (EMI) shielding materials can automatically restore their original performance after mechanical damage, and can still maintain over 20 dB EMI shielding effectiveness (EMI SE) under tensile state. In this work, a series of highly stretchable self-healing polyurethane elastomer PUBNS-X was prepared by introducing dynamic disulfide bonds, boronic ester bonds and boron-nitrogen coordination (B-N) on the polyurethane main chain. It was found that B-N coordination significantly increased the elongation at break and the tensile strength. The high dynamic reversibility of boronic ester, disulfide bond and B-N coordination bond synergistically endowed PUBNS-X with excellent temperature-triggered self-healing properties. The mechanical properties of PUBNS-X can be restored to more than 90 % at 60 °C. The pre-assembled silver nanowires (AgNWs) conductive network was then introduced into the polyurethane surface by taking advantage of the fluidity of the dynamically bonded polyurethane backbone to obtain a series of stretchable self-healing electromagnetic shielding composites (AgNWs/PUBNS-Y). The results showed that the EMI SE of AgNWs/PUBNS-Y can reach ∼55 dB, and the conductivity can be restored to 82 % of the original value after healing at 60 °C. The investigation of the electromagnetic interference shielding performance of composites under different strains showed that the EMI SE of AgNWs/PUBNS-3 can still maintain 20 dB under 90 % strain. These composites will have broad potential applications in the fields of flexible wearable electronic products, bionic intelligent materials and soft robots.

Fast room-temperature and water-insensitive self-healing polyurethane for superior composite anti-corrosion coating on Mg alloys

Self-healing polyurethane is widely applied as the anti-corrosion coating to elongate the durability of substrate. However, it remains great challenge to achieve the rapid self-healing performance at room temperature for polyurethane. And it is even more difficult to accomplish the healing under the water. Herein, a novel self-healing polyurethane, PDMS-SS-Py, is prepared to achieve self-healing within 2 h at room temperature. Even under the water, the 97.1 % self-healing efficiency is kept. Molecular dynamics (MD) simulation and density function theory (DFT) demonstrate that hydrogen bonds are pioneers in the healing process of PDMS-SS-Py and elucidate the critical items to achieve the underwater self-healing. On the basis of PDMS-SS-Py, the composite coating, MAO/8-HQ/P, is fabricated on Mg alloy along with microarc oxidation (MAO) and inhibitor 8-hydroxyquinoline (8-HQ) inserted in the micropores of MAO. The self-healing performance of composite coating is almost the same as that of isolate PDMS-SS-Py. As compared with bare Mg alloy, the impedance modulus at the low frequency (|Z|0.01Hz) is increased by 8 orders of magnitude after covering MAO/8-HQ/P coating. Even after 12 days of immersion in 3.5 wt% NaCl solution, the MAO/8-HQ/P composite coating still maintains superior anti-corrosion performance. The excellent anti-corrosion performance is contributed by the self-healing property of PDMS-SS-Py layer, the active protection of 8-HQ, and the basic protection of MAO. This work provides a general strategy for constructing durable self-healing anti-corrosion coating on Mg alloy and deepens the mechanism of polyurethane repairing processes.

Highly Tough Room-Temperature Self-Healing Polyurethane with Thermochromic Properties Based on Dynamic Covalent Bonding and Multiple H-Bonding

Highly Tough Room-Temperature Self-Healing Polyurethane with Thermochromic Properties Based on Dynamic Covalent Bonding and Multiple H-Bonding

High-Strength and Self-Healing Polyurethane Based on Dynamic Covalent Bonds for Concrete Protection

High-Strength and Self-Healing Polyurethane Based on Dynamic Covalent Bonds for Concrete Protection

Self-Healing Polyurethanes Based on Natural Raw Materials

Self-Healing Polyurethanes Based on Natural Raw Materials

Room-temperature self-healing polyurethane with superior mechanical properties based on supramolecular structure for flame retardant application

Self-healing polymers, with their ability to extend service life and conserve resources, have garnered significant attention across various fields due to their immense potential applications. However, most repairable polymers typically require high temperatures for repair, and their relatively weak mechanical properties limit their practical use. Moreover, the flammability of polymers not only poses safety hazards during use but also fails to meet specific requirements for flame retardancy in certain fields. Addressing these issues, this study successfully designed a reactive self-extinguishing room-temperature self-healing polyurethane (PU) by introducing hyperbranched catechol (DBPA) onto the PU main chain. The prepared self-healing PU elastomer (DPU) exhibited high tensile strength (∼51.2 MPa), outstanding toughness (∼119.0 MJ/m3), recyclability, and good flame retardancy. Through intermolecular and intramolecular multilevel hydrogen bonding, the prepared DPU0.6 achieved room-temperature self-healing with an efficiency of approximately 71.2 %. The results showed that the addition of trace amounts of DBPA (0.6 wt%) significantly enhanced the flame retardancy and thermal stability of DPU. Compared to DPU0, the heat release rate (HRR) of DPU0.6 decreased by approximately 13 %, the total heat release (THR) reduced by 18 %, and the time to ignition (TTI) was extended by 7 s (reduced by ∼ 21 %). This study not only provides insights into the synthesis and design of novel self-healing PU but also further expands the application scope of self-healing PU.

Bio-inspired self-healing polyurethane system: Mimicking connective tissue with hydrogen-bonding mechanism

Achieving a balance between mechanical strength and self-healing efficiency in self-healing materials is challenging yet crucial. This work introduces PCL-HBU, a polyurethane material designed for the first time to mimic collagen fibers, elastic fibers, and vascular networks of connective tissue, with excellent mechanical properties and self-healing efficiency. Meanwhile, by adjusting the 2-ureido-4-[1H]-pyrimidinone (UPy) and N,N-bis(2-hydroxyethyl)oxamide (BHO) ratio, this work creatively developed PCL-HBU3 with three distinct phase structures: amorphous region, soft segment crystallisation, and hard segment crystallisation, which approach confers excellent mechanical properties to the material. PCL-HBU3 exhibits a tensile strength of 70.0 MPa and elongation at break of 1500 %. It can recover from 600 % elongation within 20 s, achieving 100 % elongation at break self-healing efficiency. Furthermore, the composite conductive material fabricated using PCL-HBU3 as the matrix showcases self-healing abilities and holds promise in motion detection and sound recognition applications.

Fabrication of dual dynamic crosslinking polyurethane networks towards self-healing, resist fatigue, and highly stretchable ionic skins

The limited anti-fatigue performance of self-healing polyurethane elastomers under high-strain conditions restricts their application in high-performance ionic skins. Herein, a polyurethane network (PU-DDN) synergistically reversibly crosslinked by dynamic thiourethane bonds and hydrogen bonds was synthesized successfully. This dual reversibly crosslinking strategy not only endowed the polyurethane network with an excellent fatigue resistance (showing a residual strain of only 63 % after 10 uninterrupted cyclic tensile tests at 400 % strains), but also imparted it with a high strength (6.12 MPa) and stretchability (611.42 %). Owing to the thermo-reversibility of dual dynamic networks, the damaged PU-DDN heated at 100 °C for 3h could fully restore its initial mechanical properties. Subsequently, transparent stretchable ionic skins were fabricated by mixing the PU-DDN with ionic liquids. A resulting highly-sensitive ionic skin (GF1 = 1.25, GF2 = 2.01) named PU-DDN/IL20 demonstrated exceptional durability, which could produce repeatable electrical signals even after 2000 cycles of stretching to an extensive deformation of 400 %. Meanwhile, it can also monitor human motions, showcasing its promising potential in the realm of intelligent wearable applications.

Ultratough and self‐healable electromagnetic interference shielding materials with sandwiched silver nanowires in polyurethane composite films

AbstractThis study presents a facile self‐healing electromagnetic interference (EMI) shielding composite by sandwiching a layer of silver nanowires (AgNWs) between two layers of self‐healing polyurethane (SPU). The AgNWs layer forms an interconnected conductive network that effectively reflects and absorbs electromagnetic radiation, providing efficient EMI shielding. The SPU layers contribute autonomous healing of mechanical damages and restoring structural integrity and conductive pathways. The composite films exhibit remarkable EMI shielding effectiveness (SE) (up to 64.6 dB), exceptional mechanical toughness (106.4 MJ/m3), and self‐healing capabilities, outperforming conventional shielding materials. The synergy between AgNWs and SPU layers offers lightweight, flexible, tough, and self‐healing properties, making this material highly promising for applications in wearable electronics, aerospace, and automotive industries where durability and long‐term reliability are critical.Highlights Facile fabrication of sandwiched AgNWs layer between SPU films. Sandwiched AgNWs/SPU films with exceptional EMI shielding. AgNWs form conductive networks for efficient EMI shielding. Remarkable mechanical toughness of 106.4 MJ/m3 and self‐healing capability. Potential shielding materials for lightweight, wearable electronics, aerospace.

Transparent, colourless, ultra-fast room-temperature self-healing polyurethane with potential for self-repairable electrode

This work presents a novel self-healing polyurethane (Upy-PU) that strikes a remarkable balance between ultra-fast room-temperature self-healing and excellent mechanical properties. The representative material, Upy-PU1 after healing at room temperature, exhibits impressive tensile stress (7.8 MPa), extraordinary tensile strain (2379%), and excellent toughness (67.1 MJ/m3) by incorporating the rarely reported Upy-diols into the polyurethane backbone. The healing process can complete in just 30 min with the help of a minimal quantity of solvent. Intriguingly, beverages like beer, wine and Chinese baijiu can also accelerate the room temperature self-healing process, making it more feasible in practical applications. Furthermore, a thin film electrode based on Upy-PU1 demonstrates the ability to maintain electrical conductivity under 300% elongation and restores stable low electric resistance within 200% elongation after 1 h self-healing at room temperature. Notably, at 4.5 V, a conductive circuit can recover the conductivity from cutting within 5 min. These findings highlight the immense potential of Upy-PUs for applications in wearable electronics and soft robotics.

Amino-functionalized Ti3C2 and ZIF-8-induced high lubricity, friction robust self-healing polyurethanes as solid lubrication films

Self-healing polyurethane (SPU) has important applications in areas such as protective coatings, medical devices and solid lubrication. However, improving the lubricating properties of self-healing polyurethanes to reduce their friction and wear is still an important challenge. Herein, an amphoteric SPU is prepared and used as the solid lubrication matrix. NH2-Ti3C2-ZIF-8 is grown on NH2-Ti3C2 in situ to obtain NH2-Ti3C2-ZIF-8 as lubrication additive. The lubrication performance of NH2-Ti3C2-ZIF-8/SPU composites is the best when the NH2-Ti3C2-ZIF-8 content is 1.00 wt%. The coefficient of friction (COF) is only 0.10, and the wear rate is only 1.315×10−4 mm3/(N·m), which are reduced by 80.4 % and 99.4 % respectively compared with single SPU. By exploring the lubrication mechanism, it is found that NH2-Ti3C2-ZIF-8 participated in producing transfer film during friction, and the excellent lubricity and anti-wear effect of NH2-Ti3C2 and the unique adsorption and rolling effect of ZIF-8 jointly improved the friction performance of the samples. In addition, the composite material can realize rapid healing within 5 min at 75 %RH, 20℃, the self-healing efficiency can reach 84.7 %. Therefore, the SPU containing NH2-Ti3C2-ZIF-8 has potential applications in the field of solid lubricated materials.

Thermal-Driven Self-Healing Polyurethane Based on Polydopamine Nanoparticles with Enhanced Mechanical and UV Shielding Properties

Thermal-Driven Self-Healing Polyurethane Based on Polydopamine Nanoparticles with Enhanced Mechanical and UV Shielding Properties

Satisfactory Tensile Strength and Strain of Recyclable Polyurethane with a Trimaleimide Structure for Thermal Self-Healing and Anticorrosive Coatings.

Bismaleimide (BMI) is often used as the cross-linking reagent in Diels-Alder (D-A)-type intrinsic self-healing materials (DISMs) to promote the connectivity of damaged surfaces based on reversible D-A bond formation on the molecular scale. Until now, although DISMs have exhibited great potential in the applications of various sensors, electronic skin, and artificial muscles, it is still difficult to prepare DISMs with satisfactory self-healing abilities and high tensile strengths and strains at the same time, thus largely limiting their applications in self-healing anticorrosive coatings. Herein, symmetrical trimaleimide (TMI) was successfully synthesized, and trimaleimide-structured D-A self-healing polyurethane (TMI-DA-PU) was prepared via the reversible D-A reaction (cycloaddition of furan and maleimide). As a DISM, TMI-DA-PU exhibits apparently higher self-healing efficiency (98.7%), tensile strength (25.4 MPa), and strain (1378%) compared to bismaleimide-structured D-A self-healing polyurethane (BMI-DA-PU) (self-healing efficiency, 90.2%; tensile strength, 19.3 MPa; strain, 1174%). In addition, TMI-DA-PU shows a high recycling efficiency (>95%) after 4 cycles of recycling. A series of characterizations indicate that TMI provides more monoene rings as the self-healing sites, forms denser cross-linked structures compared to BMI, and is, thus, more appropriate to be used for DISM applications. Moreover, the barrier abilities of coatings can be semi-quantitatively expressed by the impedance value at 0.01 Hz (|Z|0.01Hz). The |Z|0.01 Hz value of the TMI-DA-PU coating is 3.93 × 109 Ω cm2 on day 0, which is significantly higher than that of the BMI-DA-PU coating (6.76 × 108 Ω cm2 on day 0), indicating that the denser rigid cross-linked structure of TMI results in the small porosity in the TMI-DA-PU coating, thus effectively improving the anticorrosion performance. The construction of DISMs with the structure of TMI demonstrates immense potential in self-healing anticorrosive coatings.

Synthesis of silicone-modified self-healing polyurethane coatings with MXene@fluorinated polyaniline for prolonged corrosion resistance

Synthesis of silicone-modified self-healing polyurethane coatings with MXene@fluorinated polyaniline for prolonged corrosion resistance

A super strong polyurethane elastomer with efficient self-healing performance enabled by partially mixing reversible hard domains

The reversible chain extender Diels-Alder-diol (DA-diol) containing thermally dissociable Diels-Alder adducts (DA adducts) was synthesized and combined with 1,4-butanediol (BDO) as complexed chain extenders used for preparing a transparent polyurethane elastomer (DAPU) with high mechanical strength and efficient self-healing ability by partially mixing reversible hard domains. The optimal DAPU occupies a desired high tensile strength of 65 MPa, and its elongation at break and toughness are of 1050 % and 216 MJ·m−3, respectively. Meanwhile, the DAPU-0.2 elastomer heals at 110 °C for 2 h with a healing efficiency of 95 %. The desirable mechanical strength and efficient self-healing ability are attributing to the BDO chain extended hard segments ensure the high strength at room temperature, while DA-diol chain extended hard segments endow the as-prepared DAPUs with self-healing ability at an elevated temperature. This work overall points to a strategy in designing self-healing polyurethane elastomers with markedly improved mechanical strength and efficient self-healing ability by partially mixing reversible hard domains.

Wearable skin-like polyurethane devices with variable optical functions

Skin-like wearable devices have great potential in the era of intelligence. In addition to common electronic devices, flexible photonic devices are receiving ever-increasing attention, while intelligent features of devices such as self-healing are also requested. In this work, a smart skin-like wearable photonic device constructed by combining inorganic optical materials and self-healing polyurethanes is reported. Polyurethanes with skin-like modulus are synthesized by mixing chain extender, cross-linker, and hindered phenol AO-70, demonstrating fast self-healing capability (healing efficiency of 99 % within 2 min) and good shape memory effect (shape fixation rate of 90 %). A series of flexible photonic devices are prepared by depositing optical materials on polyurethane surfaces by physical vapor deposition (PVD), with a focus on a photonic device for 1064 nm laser protection. Notably, the device exhibits a spectral recovery rate of 91.76 % after 150 % strain and a spectral recovery rate of 98.13 % after healing in 2 min, indicating superior stretchability and fast self-healing ability. This work provides a new strategy for smart skin-like wearable flexible photonic devices.

Self-Healing Polyurethane Elastomers with Superior Tensile Strength and Elastic Recovery Based on Dynamic Oxime-Carbamate and Hydrogen Bond Interactions.

The preparation of self-healing polyurethane elastomers (PUEs) incorporating dynamic bonds is of considerable practical significance. However, developing a PUE with outstanding mechanical properties and high self-healing efficiency poses a significant challenge. Herein, this work has successfully developed a series of self-healing PUEs with various outstanding properties through rational molecular design. These PUEs incorporate m-xylylene diisocyanate and reversible dimethylglyoxime as hard segment, along with polytetramethylene ether glycol as soft segment. A significant amount of dynamic oxime-carbamate and hydrogen bonds are formed in hard segment. The microphase separated structure of the PUEs enables them to be colorless with a transparency of >90%. Owing to the chemical composition and multiple dynamic interactions, the PUEs are endowed with ultra-high tensile strength of 34.5MPa, satisfactory toughness of 53.9MJ m-3, and great elastic recovery both at low and high strains. The movement of polymer molecular chains and the dynamic reversible interactions render a self-healing efficiency of 101% at 70°C. In addition, this self-healing polyurethane could still maintain high mechanical properties after recycling. This study provides a design strategy for the preparation of a comprehensive polyurethane with superior overall performance, which holds wide application prospects in the fields of flexible displays and solar cells.

Polyurethane combining preeminent toughness, puncture-resistance, and self-healing capabilities by multiple repair options based on dual dynamic covalent bonds

The development of self-healing materials has enabled the production of more reliable and intelligent materials. However, resolving the conflict between mechanical strength and self-healing efficiency as well as limited repair options of the self-healing materials is still the most pressing scientific challenge. In this study, a self-healing polyurethane with multiple repair methods is prepared by introducing disulfide bonds into thermo-reversible imine bonds-based polyurethane. The resultant polyurethane exhibits impressive comprehensive mechanical properties and preeminent repair capabilities. More importantly, damages can be repaired through various routes such as room temperature, moderate temperature, hair dryer blowing, and ethylenediamine assistance treatments. The superior mechanical properties, repetitive self-healing performance, and multiple options for repair is attributed to the cooperation of thermally reversible imine and disulfide exchanges, thermal motion of molecular chains, and dissociation/regeneration of hydrogen bonds. So this research provides numerous ideal options for repairing cracks and other damages in materials used in construction industry under different usage environments. Consequently, high-quality repairs, improved efficiency, and extended service life of construction engineering materials can be ensured.

Superior strength, highly stretchable, bionic self-healing polyurethane and its composites for flexible conductivity and self-cleaning applications

Balancing the exceptional mechanical strength and repair efficiency of self-healing materials presents a significant challenge to unlocking their full potential in practical applications. Inspired by natural spider silk and cartilage, multiple dynamic hydrogen bonds were introduced into the pre-prepared polyurethane (PU). Then modifided graphene oxide (GO) nanosheets with dynamic hydrogen bonds were added into the prepared PU to form composites (AU-PU/GDU) to establish a dense hydrogen bond network structure, providing strong interfacial interactions. The AU-PU/GDU film exhibits excellent tensile strength (39.6 MPa), high elongation at break (1155.6 %), and outstanding repair efficiency (90.3 %). Using AU-PU/GDU as the flexible base, a superhydrophobic conductive composite coating (F-AU-PU/GDU) with a contact angle greater than 150° was prepared by incorporating superhydrophobic nanomaterials. This work lays the foundation for the development of multifunctional materials through the creation of self-healing superhydrophobic conductive composite coatings, which have a wide range of potential applications.

Molecularly Engineered Tough and Room-Temperature Self-Healing Polyurethanes for Resistive Strain Sensors

Molecularly Engineered Tough and Room-Temperature Self-Healing Polyurethanes for Resistive Strain Sensors