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With isophorone diisocyanate and polytetrahydrofuran as basic raw materials, dimethylolpropionic acid and 2,3‐dihydroxypropanesulfonic acid triethylamine salt (DHPSTEA) as chain extension agents, trimethylolpropane as crosslinking agent, N, N‐dimethylethanolamine as neutralizer, the high‐solid carboxylate/sulfonate waterborne polyurethane (SC‐HWPU) was synthesized. The effect of COO−/SO3− molar ratio on the properties of SC‐HWPU was studied. Fourier transform infrared and x‐ray photoelectron spectroscopy results demonstrated that the SC‐HWPU molecular chain contained carboxylate and sulfonate groups. The results of thermogravimetric analysis, dynamic mechanical analysis, and mechanical properties of SC‐HWPU film indicated that higher DHPSTEA content was favorable for the thermostability and mechanical properties when the total dosage of hydrophilic groups was invariable. When the mole ratio of COO−/SO3− is 8:2, the solid content of the prepared SC‐HWPU3 emulsion can reach to 51.6%, which has excellent storage stability and alkali resistance stability. Subsequently, the application of SC‐HWPU emulsion on the fixed‐island type polyamide/polyethylene terephthalate copolymer superfine fiber non‐woven fabric single‐coating process was analyzed, and the water‐base superfine fiber non‐woven fabric was prepared. Scanning electron microscopy showed that there was still a large amount of SC‐HWPU filled in the superfine fiber gap after alkali‐decrement, indicating that SC‐HWPU has excellent alkali resistance. [ABSTRACT FROM AUTHOR]

It remains enormous challenges to balance the conflict between high strength and toughness mechanical properties and excellent room‐temperature self‐healing abilities of polyurethane elastomers. In this work, we report a recyclable room‐temperature self‐healing polyurethane elastomer with excellent mechanical properties. The prepared polyurethane elastomer (PU‐DA‐Zn0.50) exhibits high tensile strength of 15.33 MPa, high toughness of 76.77 MJ m−3, and high elongation at break of 1604.46% by introducing isophorone diamine (IPDA), 1‐(3‐aminopropyl) imidazole (IMZ) and zinc ions into polymer system to form a dynamic double‐cross‐linked structure (hydrogen bonds and Zn2+‐imidazole coordination bonds). In addition, the tensile strength of fractured polyurethane can reach more than 80% of the original sample after 48 h of self‐healing at room temperature without external stimuli, which is attributed to the kinetics of rapid exchange of Zn2+‐imidazole coordination bonds at room temperature. It is worth noting that the balance between excellent mechanical properties and outstanding room‐temperature self‐healing ability can be optimized by adjusting the Zn2+‐imidazole coordination bond density in the system. Moreover, the dynamic nature of the double‐cross‐linking network endows polyurethane with favorable recyclability. The above remarkable comprehensive performances reveal a great potential of PU‐DA‐Znx elastomer in the fields of wearable flexible electronic devices such as bionic skin, human motion monitoring, and soft robots. [ABSTRACT FROM AUTHOR]

The implementation of hot melt adhesives reaching structural adhesion with both impact resistance and detachability is of prospective industry value but still remains challenging. In this work, 2‐amino‐4‐hydroxy‐6‐methylpyrimidine serving as both chain extender and end‐capping reagent due to its isomerism, was developed to construct a supramolecular polyurethane‐derived hot melt structural adhesive. The as‐synthesized PUM elastomers occurs obvious decrease of molecular weight at 80°C compared to room temperature, revealing the existence of self‐complementary 2‐ureido‐4[1H]‐pyrimidinone (UPy) motifs at chain ends. This unique structure allows to chemically incorporate abundant hierarchical and quadruple hydrogen bonding moieties, which results in remarkable enhancement of shear strength, ranging from 6.4 to 16.6 MPa. More importantly, it also exhibits unique impact‐strengthening and reproducible adhering ability. The Hopkinson‐press‐bar and cyclic tensile tests manifest that quadruple hydrogen bonds play a pivotal role in buffering external forces and increasing energy dissipation when exposed to high velocity impacts. The true stress and strain synchronously increase as the strain rate augments while the shear strength can even roar up to ~18 MPa at high tensile speed. With regard to mild synthetic conditions, atomic economic use of reactants, it is promising that this material has industrial potential to be utilized in applications referred to energy‐absorption and reproducible structural adhesion. [ABSTRACT FROM AUTHOR]

Understanding how dangling fragments of polyurethanes (PU) affect its microphase separation structure and damping properties can provide insights for designing desired materials at the molecular scale. By varying the types of diol extenders (such as 1,2‐ethyleneglycol, 1,2‐propanediol, and 1,2‐butanediol), PU samples with different dangling residues were successfully synthesized. Using atomic force microscopy and small‐angle x‐ray scattering, we confirmed that the introduction of dangling chains disrupts microphase separation and demonstrated a correlation between the degree of suppressed microphase separation and the size of the dangling residues. Fourier transform infrared spectroscopy and molecular dynamics simulations confirmed that dangling chains reduce the hydrogen bonding index while increasing the phase compatibility between soft and hard segments. Differential scanning calorimetry (DSC) measurements revealed an increased glass transition temperature (Tg), indicating hindered movement of backbone segments due to dangling chains. Moreover, lengthening the dangling chains further decreased Tg. Dynamic mechanical analysis (DMA) demonstrated improved damping properties with the introduction of dangling chains, although increasing chain length led to deteriorating damping properties, consistent with observations from DSC. These findings suggest that the variations in macroscopic properties of PU induced by dangling chains are linked to hydrogen bonding interactions and micromorphology at the molecular level. [ABSTRACT FROM AUTHOR]

In order to obtain a kind of anticancer drug delivery carriers with good stability in blood circulation, high cellular uptake, and controlled drug release ability, folate‐modified polyurethane with disulfide bonds and amino groups (FPUSN) and polyurethane with carboxyl groups (PUC) were respectively synthesized. FPUSN and PUC could co‐assemble in water to form nanomicelles (FPUSN/PUC) via electrostatic interaction. When the mass ratio of FPUSN to PUC was 12, FPUSN/PUC‐12 micelles had obvious negative‐to‐positive charge‐reversal property with decreasing pH from 7.4 to 5.0. Doxorubicin‐loaded micelles (FPUSN/PUC‐12@DOX) with negative charges showed excellent stability under simulated normal physiological condition. However, the charge‐reversal happened at pH 6.5 and positive charges increased with the pH decrease. When the glutathione concentration was 10 mM, the structure of FPUSN/PUC‐12@DOX micelles was broken. So FPUSN/PUC‐12@DOX micelles exhibited significant acid/reduction‐sensitive drug release properties and then DOX could be rapidly released in simulated tumor intracellular environment. Cellular experimental results demonstrated that FPUSN/PUC‐12 micelles could enhance cellular uptake under acid condition and FPUSN/PUC‐12@DOX micelles had better anti‐proliferation effect against HGC‐27 cells at pH 6.5 than that at pH 7.4 owing to multi‐responsive synergistic effects. Therefore, FPUSN/PUC micelles will have great application potential as drug delivery carriers for enhancing anticancer efficacy. [ABSTRACT FROM AUTHOR]

Efficient and stable blue fluorescent materials are the key components of light‐emitting devices and have received wide attention. Herein, transition metal complexes Zn(5‐AQ)2, Cu(5‐AQ)2, and Cd(5‐AQ)2 are prepared by using 5‐aminoquinoline (5‐AQ) as ligand and Zn2+, Cu2+, and Cd2+ as the central ions, respectively. Then, waterborne polyurethane (WPU)‐based transition metal complexes Zn(5‐AQ)2‐WPU, Cu(5‐AQ)2‐WPU, and Cd(5‐AQ)2‐WPU with different emission wavelengths of blue fluorescence are prepared by bonding Zn(5‐AQ)2, Cu(5‐AQ)2, and Cd(5‐AQ)2 to polyurethane chains as chain extenders, respectively. Noteworthily, with the increase of transition metal ion radius (Zn2+ < Cu2+ < Cd2+), the fluorescence emission wavelengths of the complexes showed different degrees of blue‐shift, and the blue‐shifted wavelengths showed a decreasing trend. Importantly, their fluorescence colors are blue‐shifted from blue‐green to blue with different emission wavelengths after accessing the polyurethane backbone, which has potential applications in the field of tuning white LED materials. The thermal decomposition temperatures of Zn(5‐AQ)2‐WPU, Cu(5‐AQ)2‐WPU, and Cd(5‐AQ)2‐WPU are above 220°C with good thermal stability, and their fluorescence lifetimes are prolonged by 8.817, 8.896, and 6.489 ns, respectively, compared with the complexes. Furthermore, WPU transition metal complexes with water as a dispersive medium have an antibacterial efficiency of up to 100% against Escherichia coli, which is an environmentally friendly antibacterial material with broad application prospects. [ABSTRACT FROM AUTHOR]

Steel slag (SS) as solid waste, has low resource utilization efficiency and seriously endangers environmental safety and human health. To explore the potential utilization value of SS and address the flammability challenge of rigid polyurethane foam (RPUF), with a novel flame‐retardant system composed by SS and dimethyl methyl phosphonate (DMMP) was explored. The DMMP/SS system effectively improved the high temperature stability of the RPUF composites. When the mass ratio of SS and DMMP was 1:1, the limiting oxygen index of RPUF/DMMP/SS reached 23.1 vol% and UL‐94 vertical combustion tests passed V‐2 level. Upon incorporation of 15 wt% DMMP, the initial decomposition temperature (T−5 wt%) reduced to 165.3°C, a decrease of 32.2%, while the Tmax2 and residue yield at 700°C exhibited negligible alteration. The peak heat release rate of RPUF/DMMP/SS composite (118.20 W g−1) was 11.02% lower than that of pure RPUF, indicating the significant enhancement of fire safety of the composites. Results confirmed that a synergistic flame‐retardant mechanism was existed between DMMP and SS in enhancing the fire safety of RPUF composite. Introducing a 20 wt% SS content reduces the ID/IG ratio to 1.85, thereby markedly enhancing its heat resistance. This work provides a new application field of SS and paves a novel approach to enhance fire safety of polymers. [ABSTRACT FROM AUTHOR]

A self‐healing anticorrosion protective was developed for steel st‐37 exposed to the marine tidal zone, which is composed of a multi‐layer polymer coating. The coating includes zinc‐rich epoxy primer, self‐healing microencapsulated embedded epoxy, and a top coat consisting of polyurethane incorporated with silica nanoparticles. The size of microcapsules decreased with increasing agitation during encapsulation, which varies from 4 to 43 µm. Good performance was observed for producing the encapsulated particles with a size of up to 5 µm and more than 90% loading of the embedded healing agent, in which a 1680 rpm agitation along with a pH of 3 for the synthesis environment and a 130 min for the synthesis duration is set. The optimal amount of microcapsules and silica nanoparticles was 10 and 1.5 wt%, respectively. Also, the promised self‐healing anticorrosion coating leads the damaged areas to be fully healed in almost 12 h in the face of harsh conditions. In contrast to the non‐self‐healing one, the healing ability of the developed self‐healing coating shows good barrier properties and leads to a lesser loss of interface adhesion. [ABSTRACT FROM AUTHOR]

The preparation of rigid polyurethane foam with uniform pore size is extremely challenging. In this work, double‐effect baking powder was used as foaming agent, and rigid polyurethane foam with regular morphology was successfully prepared through semi‐prepolymerization. The rigid polyurethane foam apertures with regular morphology were controlled by the secondary release of CO2 when the content of baking powder is 0.30 part. Combined with theoretical calculation and experimental test, it is found that the particle size distribution, wall thickness, and hole shape are uniform, regular, thin, polygonal, and few broken holes. The compression strength, contact angle, and surface energy of the rigid polyurethane foam are 33.36 kPa, 109.6°, and 21.8 mJ/m2 after adding 0.20 part of double‐effect baking powder, respectively. By adjusting the amount of double‐acting baking powder, the porosity, mechanical properties and foam rate of the polyurethane foams could be significantly improved. Due to the molecular solvation effect, rigid polyurethane foams will deform in the water and oil due phase, but it can remain stable for a long time at room temperature without solvent. It provides a new method for the preparation of rigid polyurethane foam, which is expected to be widely used in transportation and other fields. Highlights: Baking powder was firstly used as a foaming modifier for rigid polyurethane.Baking powder releases CO2 twice to ensure uniform structure of polyurethane cell.Rigid polyurethane foam has long‐term stability and regular, uniform cell holes.The porosity and mechanical properties of foams could be significantly improved.Foaming mechanism of rigid polyurethane using baking powder was firstly revealed. [ABSTRACT FROM AUTHOR]

Due to its excellent durability and steady mechanical qualities, three‐dimensional porous polyurethane foam (PUF) presents a wide range of possibilities for flexible piezoresistive sensors. Its extreme flammability, poor electrical conductivity, and susceptibility to outside factors present serious difficulties, though. In this study, a waterborne polyurethane‐coated flexible PUF sensor that incorporates reduced graphene oxide (RGO) and polyaniline (PANI) through a methodical, step‐by‐step dip‐coating methodology is successfully developed. The final product has a water contact angle of 133°, which improves its ability to adapt to a variety of environmental circumstances. Flexible graphene sheets are incorporated to improve heat resistance and flame retardancy, and PANI and RGO provide strong bonding to the PUF framework, ensuring outstanding structural stability even after 1500 cycles. The flexible foam sensor shows promise for use in flexible piezoresistive sensors and electronic skin due to its remarkable strain monitoring range of up to 70%, quick response time of 0.39 s in sensitivity experiments, and adaptability to different physical activities like walking and gesturing. [ABSTRACT FROM AUTHOR]

Highlights In this study, the effects of various weight percentages of montmorillonite nanoclay particulates (0%, 1%, 3%, 5%, 7%, and 9%) are fabricated using the hand‐layup technique, and their physical properties are thoroughly examined. To accurately extract the specific qualities of the matrix materials, the concept of interpenetrating polymer networks (IPNs) is implemented by blending 70% epoxy and 30% polyurethane, thereby achieving meticulous control over the individual matrix properties. Besides, E‐glass fiber (biaxial woven mat) is selected as the reinforcement to provide structural rigidity to the IPN laminate. As well, to comprehensively evaluate the mechanical properties of the nanoclay and E‐glass fiber‐reinforced composites, a series of tests are conducted according to ASTM standards. These tests included dynamic mechanical analysis (with a tan δ value of 0.171), tensile strength (345.71 MPa), flexural strength (312.67 MPa), impact strength (22 kJ/m2), heat deflection analysis (HDT at 88°C), and free vibration analysis (with natural frequencies of Mode I—25.12 Hz, Mode II—158.36 Hz, Mode III—424.87 Hz, and Mode IV—736.72 Hz). Out the study, reveals that, incorporating 5% nanoclay significantly enhanced all measured properties to their maximum extent. Additionally, to gain a better understanding of the micromechanics between the fiber, particulates, and matrix, the fractured specimens are thoroughly analyzed using scanning electron microscopy. Also, study aims to employ nanoclay‐incorporated composite materials in various advanced applications such as packaging delivery systems, military systems, magnetic shielding operations, detectors, and information technology industries. Utilization of nanoclay significantly enhances the strength of composites. IPN laminates were fabricated with filler loads ranging from 0% to 7%. Mechanical properties of IPN laminates have been comprehensively investigated. DMA and vibration tests conducted to assess the aptness of the filler inclusion. SEM analyses clearly revealed superior compactness with 5% nanoclay addition. [ABSTRACT FROM AUTHOR]

In this work, FR‐PNX, an alkylphosphate oligomer was introduced into rigid polyurethane foam (RPUF) to fabricate FR‐PNX/RPUF composites. The flame retardancy, thermal stability, and combustion properties of composites were investigated by limiting oxygen index (LOI), thermogravimetric (TG), microcalorimetry (MCC), scanning electron microscopy (SEM), et al. The flame retardancy tests demonstrated that the incorporation of 50 phr of FR‐PNX yielded composites that the highest LOI of 23.6 vol% and achieved a V‐0 rating in the UL‐94 test. TG results indicated that FR‐PNX promoted the decomposition of FR‐RPUF in the process, but enhanced the high‐temperature stability of the composites. MCC analyses revealed that the addition of FR‐PNX suppressed the heat release during combustion, and FR‐PNX50/RPUF exhibited the lowest total heat release of 17.3 MJ/m2, a 35% reduction compared to the pure sample. Moreover, the peak heat release rate was decreased to 83.1 W/g, representing a 46.9% reduction compared to pure RPUF. SEM and Raman analyses of the char residue demonstrated that the incorporation of FR‐PNX facilitated the formation of a dense and continuous char layer in the FR‐RPUF, with increased graphitization degree of the char layer, thereby enhancing the composite's fire resistance through the development of a more stable fire barrier. [ABSTRACT FROM AUTHOR]

A green method to synthesize self‐matting waterborne polyurethane acrylic hybrid emulsion with hydrophobic function is introduced in this study. A reactive waterborne polyurethane (RWPU) dispersion containing unsaturated CC double bonds was prepared from epoxidized soybean oil. Subsequently, the RWPU dispersion was copolymerized with fluorinated monomers of different carbon chain lengths to prepare polyurethane acrylic hybrid emulsion (PUF). The results revealed the gloss levels of PUF films to be as low as 12.4 gloss units at 60°. The morphology of PUF films was observed by scanning electron microscope and three‐dimensional surface profilometer, and the relationship between surface roughness and gloss was discussed in detail. In addition, thermal gravimetric analysis was conducted to determine the thermal stability of the PUF films, and the results denoted that these PUF films exhibited excellent thermal stability. Comprehensive performance tests indicated that the RWPU dispersion, which was copolymerized with hexafluorobutyl methacrylate at a weight of 10%, exhibited a low gloss, a high contact angle of 120°, and a high elongation percentage of 423%. Furthermore, the dynamic light scattering results showed small average particle size, revealing the excellent storage stabilities. [ABSTRACT FROM AUTHOR]

Isocyanate‐based monomers and polymers have found widespread industrial application; however, the realization of green water‐based products via the preparation of stable isocyanate aqueous emulsions remains challenging. Herein, a series of organosilicon and organofluorine synergistically modified amphiphilic branched polyurethanes (HBWPU), synthesized by grafting perfluorohexyl ethanol semi‐terminated isophorone diisocyanate (IPDI) onto a hydrophilic polyurethane prepolymer, is presented. Subsequently, using a physical mixing method, stable diisocyanate emulsions are fabricated by preparing diisocyanate latex particles with IPDI as the core and hyperbranched water‐based polyurethanes (HBWPU) as the shell. Structural investigations showed that the branching degree and fluorine content of the HBWPU significantly affects the stability of the diisocyanate emulsions. Increasing the degree of branching from 0.34 to 0.86 causes the amount of residual isocyanate (NCO) groups to decrease from 20.1% to 16.7%. In contrast, an increase in the fluorine content from 0% to 17.8% increases the amount of residual NCO groups from 11.5% to 24.6%. Thus, HBWPU can be used as an emulsifier to prepare waterborne diisocyanate cross‐linking agents. Such polyurethane‐coated isocyanate aqueous emulsions can increase the hardness and significantly improve the acetone resistance of hydroxyl polyacrylate resins. [ABSTRACT FROM AUTHOR]

With rapid advances in electronic and communication technology, electromagnetic interference and other problems are becoming increasingly prominent. Thus, electromagnetic interference shielding materials have recently garnered extensive attention. In this study, a multi‐walled carbon nanotube/polyurethane/non‐woven electromagnetic shielding material (CPNW) is developed using impregnation and nonsolvent‐induced‐phase separation techniques. Utilizing a three‐dimensional nonwoven network as the substrate, the "nonwoven fabric‐polyurethane‐carbon nanotube" composite is impregnated and cured via the non‐solvent‐induced‐phase separation method, resulting in a distinctive porous dual‐network structure that ensures robust interfacial bonding between carbon nanotubes, nonwoven fabric, and polyurethane. At a carbon nanotube content of 10% (based on the mass of nonwoven fabric), CPNW exhibited an electromagnetic interference shielding effectiveness of 28.8 dB, a thermal conductivity of 0.127 W m−1 K−1, and a burning time of 1 min and 15 s, demonstrating outstanding electromagnetic shielding, flame retardant, and infrared stealth capabilities. Overall, this study laid a theoretical groundwork for the development of multifunctional non‐woven electromagnetic shielding materials with widespread application potential in aerospace, military, artificial intelligence, and wearable electronics. [ABSTRACT FROM AUTHOR]

A UV‐ and thermo‐responsive polyurethane‐acrylate prepolymer was synthesized from palm olein (POo) via a non‐isocyanate route. The process included epoxidation of POo, carbonation of epoxidized palm olein (EPOo) into polycyclic carbonate in a solvent‐free and mild condition (100°C, 1 atm), followed by reacting with ethylene diamine and acrylic acid. The chemical structure of the non‐isocyanate polyurethane‐acrylate (NIPUA) prepolymer was elucidated by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform‐infrared spectroscopy (FTIR), while weight average molecular weight of NIPUA was determined by gel permeation chromatography (GPC). The NIPUA (0–20 wt%) was incorporated with thermoplastic elastomer (TPE) as a plasticizer and cured under UV light and thermal stimulations. The cured NIPUA/TPE films were characterized by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test. Under UV and thermal stimulations, the NIPUA/TPE demonstrated enhanced tensile properties (elongation at break >1280%, Young's modulus ~25 MPa), thermal properties (lower Tg), lower water contact angle, and shortened curing time as compared with the blank TPE. The 20 wt% NIPUA/TPE films exhibited susceptibility to enzymatic biodegradation and noncytotoxic to HEK 293 cells in vitro, demonstrated it's potential as a UV‐ and thermo‐responsive plasticizer for TPE in manufacturing of medical devices. [ABSTRACT FROM AUTHOR]

In this study, we investigate the fabrication of ambient room temperature responsive shape memory polyurethane (SMPU)‐coated fabric using a simple dip coating method, aiming to enhance the shape memory response of smart textiles. Two SMPU were synthesized using different chain extender 1,4 butanediol (BDO‐SMPU) and polyethylenimine (PEI‐SMPU). Critical parameters such as SMPU concentration, dwell time, and coating solution temperature are optimized to ensure exceptional shape memory performance while also maintaining the fabric's handle, comfort, and durability. We determined that PEI‐SMPU/Cotton fabric exhibits superior memory performance, with a 90.2% shape recovery at a 1% PEI‐SMPU concentration. Conversely, BDO‐SMPU fabric demonstrated a 75.8% shape recovery under different conditions (10% SMPU concentration, 50°C solution temperature). Furthermore, shape recovery is influenced by programming temperature and load; at 35°C and 10 N load, PEI‐SMPU/Cotton significantly outperforms BDO‐SMPU/Cotton, showing about 20% improvement in shape recovery. This study indicates that modifying SMPU from BDO‐SMPU to PEI‐SMPU can notably enhance shape recovery performance at 35°C, marking a significant advancement in human body temperature responsive smart fabric technology. [ABSTRACT FROM AUTHOR]

The utilization of leather waste (LW) in a polyurethane (PU) matrix makes a smart and novel shape stable phase change material (SSPCM). This is essential for sustainability as it reduces landfill waste after use. The PU is synthesized in bulk with a 90% yield, using biodegradable polycaprolactone diol and bio‐based polyol (castor oil), along with tolylene‐2,4‐diisocyanate. PL and PLG composites are prepared by blending of constituent components PU (P), LW (L), and poly(glycidyl methacrylate) (PGMA, G), as specified by their code names. Role of LW (hydrogen bonding and chemical crosslinking) and morphology are elucidated by FTIR and SEM, respectively. Self‐healing time (2 h), shape fixity ratios (Rf) (PL: 60–80% and PLG: 60–70%) and shape recovery ratios (Rr) (100% for both) are determined at 60°C. PLG displays faster shape recovery in water (<30 s) compared to air (>300 s). Shape stability and thermal properties of the SSPCM are examined using the temperature responsive leakage study, TGA, and DSC. This research introduces a new approach for using leather waste (LW) in SSPCM, with self‐healing and 100% Rr. This material may find application where SSPCM with high durability and flexibility is essential such as textile and footwear materials. [ABSTRACT FROM AUTHOR]

Shape memory polymers have been widely researched to develop multifunctional materials that respond smartly to external stimulations and programmed signals. Among them, shape memory polyurethane (SMPU) is drawing great attention owing to its highly tunable properties and ease of integrating new functions. However, the effect of urea bonds on SMPU elastomers has rarely been investigated because of the extreme reactivity of amine crosslinkers. In this study, we used diethanolamine (DEOA), which contains a secondary amine, as the crosslinker for SMPU synthesis. Unlike other crosslinkers containing primary amines, they can form urea bonds in a more gentle manner. The urea bonds reinforce the intermolecular interactions between the hard segments with strong hydrogen bonding, thus increasing the phase separation and degree of crystallization. Consequently, the urea‐containing SMPU exhibits improved mechanical strength and shape memory abilities for both fixing and recovery. Moreover, the transcarbamoylation reaction, which enables the reconfiguration of the original shape, is observed. The introduction of the urea bonds into the SMPU elastomer can be beneficial in achieving flawless shape memory performances in various sensitive applications. [ABSTRACT FROM AUTHOR]

Flexible electronics are striving in modern society, and they impose harsh and urgent requirements for flexibility on electronic package substrates. However, traditional materials, including ceramics, metals, or polymers are lack of flexibility. Herein, a polyurethane named PU‐D1Q1VF1 is proposed via incorporating carefully selected biobased units and synergistic dynamic bonds, and the PU‐D1Q1VF1 not only meets the basic requirements of flexibility but also possesses properties of self‐heal, UV‐protection, reprocessability, and degradability. The polycaprolactone diol (PCL diol) was employed as the soft segment, and the bis(2‐hydroxyethyl) disulfide (HEDS) and lignin derived model monomer hydroquinone were selected as chain extenders. Moreover, carefully synthesized bio‐based monomer (E)‐4‐(((furan‐2‐ylmethyl)imino)methyl)‐2‐methoxyphenol (VF) was used as the capping agent, which could facilitate the self‐healing process of the PU‐D1Q1VF1. [ABSTRACT FROM AUTHOR]

The primary objective of this research is to fabricate semi‐interpenetrating polymer networks (semi‐IPNs) via in‐situ polymerization of methyl methacrylate (MMA) within a polyurethane (PU) framework. To produce polymethyl methacrylate (PMMA) from MMA in the PU matrix, solution polymerization was utilized in the following weight ratios: 30/70, 50/50, 70/30, and 90/10. The effective formation of semi‐IPNs of PU/PMMA was confirmed by several techniques. Fourier transform infrared (FTIR) proves that no new chemical bonds formed between the semi‐IPNs, and only physical interactions were present, and X‐ray diffraction (XRD) techniques tell about the amorphous nature of these semi‐IPNs. The field emission scanning electron microscope (FESEM) and atomic force microscope (AFM) were utilized to examine the morphology of PU/PMMA semi‐IPNs. In contrast to alternative semi‐IPNs, 70/30 and 90/10 PU/PMMA exhibit a uniform morphology devoid of phase separation. Furthermore, the significant thermal stability and transitions of these semi‐IPNs were assessed using a thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, the mechanical analysis indicates that among the different percentages of PU/PMMA, 70/30 PU/PMMA exhibits the highest tensile strength of approximately 50.5 MPa. The observed enhancement in mechanical strength can be attributed to interpenetrating networks (IPNs) formed between the constituents. The synthesized PU/PMMA semi‐IPNs have potential in various fields, including medical devices, automotive components, sports, and other advanced applications. [ABSTRACT FROM AUTHOR]

Synthesis of polyurethane‐type poly[3]rotaxanes is achieved by polyaddition between a cyclodextrin (CD)‐based [3]rotaxane diol and various diisocyanate species, which provide a more defined structure compared to conventional polyrotaxane syntheses. In this study, hydroxyl groups on CDs of [3]rotaxane diol are initially acetylated, and deprotected after the polyaddition to introduce polyurethane backbone structure into polyrotaxane framework. Despite a relatively complicated chemical structure, [3]rotaxane diol monomer is successfully synthesized in a high yield (overall 67%) without any taxing purification process, which is beneficial for practical applications. The polymerization itself proceeds well under a standard polyaddition reaction condition to afford corresponding polyurethanes around 80% yield with Mn > 30 kDa. The poly[3]rotaxanes show different aggregation behavior or optical properties, whether or not acetyl groups are present, and are analyzed by XRD, SEM, and fluorescence measurements. [ABSTRACT FROM AUTHOR]

High‐energy‐density and cost‐effective lithium‐rich oxides (LRO) are considered as the promising cathode materials for the next‐generation lithium‐ion batteries. Nevertheless, the elevated cut‐off voltage and the complex interface interactions have presented significant challenges that can lead to material degradation. Specifically, the inevitable release of lattice oxygen and the highly reactive interface‐driven irreversible migration of transition metal (TM) ions in LRO make the construction of a robust interface extremely important. Herein, an effective and efficient coating approach is applied to stabilize the interface structure of LRO by introducing a coordination bond between the strong ligand of polyurethane (PU) and the surface of LRO particles. This functional coating stabilizes the crystal field stabilization energies of LRO by acting as a strong ligand in spectrochemistry to form a coordination bond with Mn4+ in Li2MnO3 at high voltage. Consequently, irreversible oxygen release and TM ions migration are greatly inhibited. Overall, the LRO‐PU cathode exhibits superior electrochemical cyclability with a retention of 80.0% at 1C after 300 cycles and enhanced rate capability with a retention of 80.9% at 0.1C after rate cycles, marking a significant step toward commercial implementation. [ABSTRACT FROM AUTHOR]

A highly flexible, tunable morphology membrane with excellent thermal stability and ionic conductivity can endow lithium metal batteries with high power density and reduced dendrite growth. Herein, a porous Polyurethane (PU) membrane with an adjustable morphology was prepared by a simple nonsolvent–induced phase separation technique. The precise control of the final morphology of PU membranes can be achieved through appropriate selection of a nonsolvent, resulting a range of pore structures that vary from finger–like voids to sponge–like pores. The implementation of combinatorial DFT and experimental analysis has revealed that spongy PU porous membranes, especially PU−EtOH, show superior electrolyte wettability (472%), high porosity (75%), good mechanical flexibility, robust thermal dimensional stability (above 170 °C), and elevated ionic conductivity (1.38 mS cm−1) in comparison to the polypropylene (PP) separator. The use of PU−EtOH in Li//Li symmetric cell results in a prolonged lifespan of 800 h, surpasing the longevity of PU or PP cells. Moreover, when subjected to a high rate of 5 C, the LiFePO4/Li half‐cell with a PU−EtOH porous membrane displayed better cycling performance (115.4 mAh g−1) compared to the PP separator (104.4 mAh g−1). Finally, the prepared PU porous membrane exhibits significant potential for improving the efficiency and safety of LMBs. [ABSTRACT FROM AUTHOR]

Toughening thermo‐setting resins with both high impact strength and tensile strength is a challenging issue. In this study, a novel cross‐linked polyurethane nano spheres for toughening epoxy resin were prepared by self‐emulsification method with hexamethylene diisocyanate trimer (HDI trimer) and diethylene triamine (DETA) as the crosslinkers. The structure, morphology and particle size of cross‐linked polyurethane nano spheres were investigated by infrared spectroscopy, laser particle size analyzer and scanning electron microscopy. Results showed that the prepared cross‐linked polyurethane nano spheres showed spherical shape and had the size in the range from 40 to 258 nm. The application of cross‐linked polyurethane nano spheres in toughing epoxy resin was investigated. The results showed that cross‐linked polyurethane nano spheres can be uniformly dispersed in epoxy resin and no obvious aggregation phenomenon was observed. And the tensile strength and impact strength of epoxy resin can be increased simultaneously when the cross‐linked polyurethane nano spheres were used in toughening epoxy resin. With the increase of the amount of polyurethane nano spheres in epoxy resin, both the tensile strength and impact strength of epoxy resin had the trend of first increase and then decrease. The amount of HDI trimer in the microspheres had a great impact on their toughening effect on epoxy resin. When the cross‐linked polyurethane nano spheres contained HDI trimer content of 12 wt% and the amount of the nano spheres in epoxy resin was 8 wt%, the impact strength of the epoxy resin can reach as high as 23 kJ/m2, which was 4.33 times that of pristine epoxy resin. And the tensile strength of toughened epoxy resin was 50.7 MPa, which was at same level of that of pristine epoxy resin. The results of this study indicate that the cross‐linked polyurethane nano spheres have a great potential in toughening thermo setting resins, such as epoxy resin. [ABSTRACT FROM AUTHOR]

Waterborne superhydrophobic coatings have attracted widespread attention. However, organic solvents, fluorine-containing compounds, and complex operational technologies hinder superhydrophobic coatings development severely. Herein, A simple method of preparing water-based superhydrophobic coatings by one-step spraying without organic solvent and fluorine is reported. The particles of silicon dioxide (SiO2) was modified by isobutyltriethoxysilane (IBTS), then combined with waterborne acrylic polyurethane (WPUA) and phenolic resin (PF), baked at 110°C to fabricate superhydrophobic coatings. According to the contact Angle (CA), hardness, adhesion, and other parameters, the ratio of SiO2 and PF of the composite coatings was optimized. Results showed that the superhydrophobicity and physical properties of the coating are the most exceptional at the content of SiO2 is 0.6 g, and the PF is 25%. In addition, related experimental results show that the coatings have good water resistance and self-cleaning ability, the special nano/micro structure of the coatings also endows it excellent abrasion resistance. Exceptional hydrophobicity and physical properties meeting the actual application conditions of superhydrophobic coatings. Therefore, the simple method for preparing superhydrophobic coatings has great application prospects. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR)‐triggered shape memory hydrogels with promising mechanical strength hold immense potential in the field of biomedical applications and soft actuators. However, the optical and mechanical properties of currently reported hydrogels usually suffer from limited solubility and dispersion of commonly used photothermal additives in hydrogels, thus restricting their practical implementations. Here,, a set of NIR‐responsive shape memory hydrogels synthesized by polyaddition of diisocyanate‐terminated poly(ethylene glycol), imidazolidinyl urea (IU), and p‐benzoquinone dioxime (BQDO) is reported. The introduction of IU, a hydrogen bond reinforcing factor, significantly enhances the mechanical properties of the hydrogels, allowing for their tunable ranges of the ultimate tensile strength (0.4–2.5 MPa), elongation at break (210–450%), and Young's modulus (190–850 kPa). The unique hydrogels exhibit an intrinsic photothermal effect because of the covalently incorporated photothermal moiety (BQDO), and the photothermal supramolecular hydrogel shows controllable shape memory capabilities characterized by rapid recovery speed and high recovery ratio (>90%). This design provides new possibilities for applying shape memory hydrogels in the field of soft actuators. [ABSTRACT FROM AUTHOR]

Submicron‐textured surfaces have been a promising approach to mitigate biofilm development and control microbial infection. However, the use of the single surface texturing approach is still far from ideal for achieving complete control of microbial infections on implanted biomedical devices. The use of a surface topographic modification that might improve the utility of standard antibiotic therapy could alleviate the complications of biofilms on devices. In this study, we characterized the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa on smooth and submicron‐textured polyurethane surfaces after 1, 2, 3, and 7 days, and measured the efficacy of common antibiotics against these biofilms. Results show that the submicron‐textured surfaces significantly reduced biofilm formation and growth, and that the efficacy of antibiotics against biofilms grown on textured surfaces was improved compared with smooth surfaces. The antibiotic efficacy appears to be related to the degree of biofilm development. At early time points in biofilm formation, antibiotic treatment reveals reasonably good antibiotic efficacy against biofilms on both smooth and textured surfaces, but as biofilms mature, the efficacy of antibiotics drops dramatically on smooth surfaces, with lesser decreases seen for the textured surfaces. The results demonstrate that surface texturing with submicron patterns is able to improve the use of standard antibiotic therapy to treat device‐centered biofilms by slowing the development of the biofilm, thereby offering less resistance to antibiotic delivery to the bacteria within the biofilm community. [ABSTRACT FROM AUTHOR]

Due to their unique mechanical and thermal properties, polyurethane foams are widely used in multiple fields of applications, including cushioning, thermal insulation or biomedical engineering. However, the way polyurethane foams are usually manufactured ‐ via chemical foaming ‐ produces samples where blowing and gelling occur at the same time, resulting in a morphology control achieved by trial and error processes. Here, a novel strategy is introduced to build model homogeneous polyurethane foams of controlled density with millimetric bubbles from liquid templates. By producing a polyurethane foam via physical bubbling without a catalyst and gently depositing a secondary foam containing catalyst on the top of this first foam, it is possible to take advantage of drainage mechanisms to trigger the solidification of the bottom foam. The characterization of the samples performed by X‐ray microtomography allows to study quantitatively the structure of the final solid foam, at the global and at the local scale. Using the tomographic 3D images of the foam architectures, the superimposed foam technique introduced in this article is shown to be promising to produce foams with a good homogeneity along the vertical direction, with a density controlled by varying the concentration of catalyst in the secondary foam. [ABSTRACT FROM AUTHOR]

A thermal conductive structural adhesive (TCSA) plays a crucial role in battery performance and safety. TCSA made of polyurethane (PU) has not only a good thermal conductivity but also good mechanical strength and substrate bonding strength. However, it has to be cost‐effective and easy to be prepared. This work aims to synthesize a series of castor oil‐based PU TCSAs with different amounts of thermal conductive powder using commercially available castor oil polyols, isocyanates, Al2O3, and additives. The shear strength of the TCSA containing 88% thermally conductivity powder reached 5.6 MPa, which was similar to that without the thermal conductivity fillers, but its toughness significantly decreased. Its thermal conductivity was as high as 1.8 W/mK, and it was thermally stable below 270°C. [ABSTRACT FROM AUTHOR]

In the burgeoning field of bioinspired materials, the principles governing biological perception and self‐healing drive advancements in biomimetic mechano‐responsive materials, seamlessly integrating ionic signal sensing with self‐healing. While current research often emphasizes individual functionalities, the concurrent enhancement of both self‐healing and sensitivity in iontronic skins is often overlooked. Drawing inspiration from transmembrane proteins like TSP‐15, Piezo 1 and Piezo 2, renowned for recruiting repair factors, multifunctional molecular‐ionic regulatory sites are constructed within a polyurethane/ionic liquid composite system, leading to the development of a mechano‐responsive elastomer (i‐DAPU) that exhibited both rapid self‐healing (72 µm min−1) and impressive sensitivity (7012.05 kPa−1). Leveraging the dual functionalities of i‐DAPU in tandem with deep learning algorithms, a sophisticated system is devised for intelligently analyzing neural conditions in comatose patients based on muscle strength, achieving a remarkable 99.2% accuracy rate, holding significant promise for healthcare applications. [ABSTRACT FROM AUTHOR]

Self‐repairing materials aim to replicate nature's repair mechanisms, but their current properties are inadequate for commercialization due to the trade‐off between repair and mechanical properties. An environmentally responsive low‐temperature self‐healing aqueous polyurethane with different sequence structures was developed in which the WPU‐MD/APDS system exhibited excellent performance. Statically, the incorporation of MD (1,8‐diamino‐P‐menthane) enhances hydrogen bonding within the system and facilitates reversible weak dynamic bonding; microphase separation enables aggregation of disulfide bonds in the hard‐phase domain, thereby improving disulfide bond exchange rates. Dynamically, the inclusion of MD introduces a rigid ring structure and promotes microphase separation with increased hydrogen bonding, leading to enhanced mechanical properties of the materials. The material exhibited tensile strength of 27.37 MPa, elongation at break of 1353%, excellent elastic recovery ability, and high tensile toughness of 136 MJ m−3; a sample with thickness of 0.2 mm lifted weight greater than its own weight into 40,000 times without damage recovery at 40°C. Rheological analysis confirmed its self‐healing property at room temperature. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) has been applied to high‐performance laminated glass depending on its high impact strength and bonding properties. The utilization of various polyurethane molecular structures in laminated glass is scarcely reported. The selection and application of chain extenders are crucial for TPU performance. In this work, aliphatic polyurethane film with high strength has been successfully synthesized, incorporating chain extender of poly(propylene glycol) bis(2‐aminopropyl ether) (PEA230). The films with melting point above 80°C were prepared by adjusting the proportion of dimethylglyoxime (DMG), while simultaneously monitoring the thermal behavior of the samples by DMA. Results indicate that combining PEA230 and DMG in a 1:1 molar ratio yields the hydrogen bonding degree of 85.77%, toughness of 43.14 MJ m3, and shear stress of 1.8 MPa for the polyurethane film. Subsequently, laminated glasses based on the polyurethane film with different thermal properties were constructed successfully, and their super strong impact resistance was confirmed through falling ball impact experiments. [ABSTRACT FROM AUTHOR]

The contradiction between the migration rate of molecular chains and mechanical strength has always been a key factor affecting the practical application of self‐healing anticorrosion coatings. In this paper, a series of supramolecular self‐healing elastomers (SPU‐MP) were prepared by the reaction of diphenylmethane diisocyanate and polyether amine. The results shown that the proportion of polyetheramine D230 (D230) in molecular segments affects the hydrogen bond density between molecular chains, thereby affecting the self‐healing efficiency and mechanical strength of SPU‐MP. When the ratio of D230 and polyetheramine D400 (D400) is 2:8, the tensile fracture strength of SPU‐MP8 is 5.08 MPa, and the self‐healing efficiency reaches 82.1% after 10 h of repair at room temperature. Further increasing the ratio of D230 increases the relaxation time of the molecular chain due to the increase in hydrogen bond density, resulting in a decrease in the self‐healing efficiency of SPU‐MP. The results of electrochemical experiments and neutral salt spray experiments indicate that the anticorrosion coating prepared by SPU‐MP8 exhibits good self‐healing performance. After immersing in 3.5 wt.% NaCl solution for 35 days, the low‐frequency impedance modulus of the intact coating and the scratch coating were both higher than 107 Ω cm2, still shown good anticorrosion ability. [ABSTRACT FROM AUTHOR]

Because of the significant advantages of bone adhesives compared with traditional mechanical fixation, many scholars have studied polyurethane bone adhesives. However, polyurethane will release a lot of heat in the reaction process, producing high temperature. The high temperature does not only easily cause a human discomfort but also will destroy the tissue structure of human. In this paper, a new polyurethane composite based on phase transition materials and hydroxyapatite is prepared to reduce released heat for application in bone binder. The mechanical properties, adhesive strength, and released heat‐induced temperature of polyurethane composite are investigated in detail. It exhibits good viscoelastic performance with a large elastic deformation (>30%) and good adhesive strength (>0.2 MPa). Furthermore, the released heat of polyurethane composite is effectively reduced, in which the temperature drastically decreases from 110.4 to 41.8°C. The work does not only confirm formation of high‐performance bone binder but also provides a new method to reduce released heat of polyurethane for various applications. [ABSTRACT FROM AUTHOR]

In this study, flame retarded polyurethane vitrimers, namely vitrimeric poly(isocyanurate urethane)s (VPICUs), were synthesized successfully by melting polycondensation simply from tris(2‐hydroxyethyl)isocyanurate and dicarbamates. By increasing the methylene number in dicarbamates from 4 to 10, the VPICUs exhibit superior mechanical performance with elongation at break increases from 20% to 350% while the tensile strength decreases from 80 to 32 MPa, and the toughness can be significantly enhanced from 9 to 90 J/cm3. With a mass fraction of isocyanurate ring at 26.6%, for VPICU10‐2.5/2, the flame retardancy is found to be the most excellent, with a UL‐94 rating at V‐0 and a LOI value at 25.9%. VPICU10 samples exhibit substantial relaxation behavior at higher temperature, and the network rearrangement activated by transesterification and transurethanization reactions offers the reprocessability without losing the properties. This work provides new insights into the construction of sustainable and high‐performance flame retarded polymer materials. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess, characterize, and forecast the aging effects on the mechanical properties of a vegetable‐based polyurethane foam (PUF) derived from castor oil under elevated relative humidity conditions and at two distinct load orientations (aligned with the expansion direction and perpendicular to it). Ten specimens were subjected to temperatures of 60, 75, and 90°C, along with a relative humidity of 90%, for a duration of up to 60 days. Compression tests, following ASTM D1621‐16 standards and supplemented by 3D digital image correlation, revealed nearly isotropic behavior with marginally lower compression strength in the expansion direction. On the other hand, the strength of the foams at 90°C was higher in that direction. This led to a smaller activation energy (Ea) in this property, which ended up showing a shorter lifespan prediction considering the strength retention in this direction. The stiffness values were proportionally more similar in both directions than the strength ones and this was observed in the Ea for those curves. In contrast to several other foams and polyurethanes, the one examined in this study exhibited consistently higher Ea values for its mechanical properties, particularly in the transverse direction to expansion, surpassing 94 kJ/mol. This indicates a robust diffusion and chemical stability, suggesting its potential for prolonged utilization compared to conventional oil‐based foams. A prediction was made that this foam would lose 50% of its stiffness and strength in around 9.8 and 9.5 years at 20°C, respectively, considering the directions more sensitive to the aging process. This research offers valuable insights for predicting lifespan based on operating temperatures and property retention needs, contributing to the advancement of sustainable materials in structural applications. Highlights: Fifty specimens investigated for each of two directions.Evaluation of vegetable‐based PUF aging process unveils density changes.Unique behavior noted: different Ea values for each direction.High Ea values indicate enhanced mechanical stability over oil‐based foams.Lifespan prediction enhances material application prospects. [ABSTRACT FROM AUTHOR]

High thermally conductive polymer composites have garnered significant attention due to their exceptional performance, given the ever‐decreasing size of electronic devices and the rise in power densities. Herein, a new three‐dimensional (3D) thermal conductivity network structure has been successfully prepared using double fillers of nickel foam (NF) and modified silicon carbide particles (KSiC). The study compared the effect of different filler contents on the thermal conductivity of composites. Compared to conventional composites, those based on 3D filling networks have significantly improved thermal conductivity. The thermal conductivity of the NF/KSiC/PU composite containing 50 wt% KSiC was 1.18 Wm−1 K−1, exceeding the cumulative thermal conductivity of the NF/PU and KSiC/PU 50 wt% composites, and 637.5% greater than that of neat PU. Meanwhile, the synthesized NF/KSiC/PU composite maintained a high electrical resistivity above 1012 Ω·cm and good mechanical properties. This approach might offer novel solutions for developing high‐quality packaging materials for advanced electronic devices with exceptional thermal and mechanical properties. Highlights: Using SiC and NF Constructs a dual filler network.The dual filler thermal conductivity network can generate synergistic effects.Improving thermal conductivity compared to original polyurethane.Maintaining a high electrical resistivity and good mechanical properties. [ABSTRACT FROM AUTHOR]

Shrinking resources of fossil oil prompt search for other biosphere‐present substrates to obtain polyols, which in turn are basic components to synthesize polyurethane foams (PUF). Widely available examples are biopolymers like starch, cellulose, and chitosan. It has been shown that oligomeric chitosan as well as water soluble chitosan can be applied to obtain polyols and rigid PUF of good performance properties. In this paper, the higher molecular mass chitosans, insoluble in organic solvents and water, were converted to polyols and ultimately into foamed polyurethane plastics. The polyols were characterized by the infrared spectra (IR), 1H‐NMR, and MALDI‐ToF methods. Their properties, such as density, viscosity, surface tension and hydroxyl numbers, were determined. The PUF were obtained from these polyols of various molecular mass. The biodegradable, rigid PUF of enhanced thermal resistance were obtained. Their physical parameters like apparent density, water volume absorption, dimension stability, heat conductance, compressive strength, and heat resistance at 150 and 175°C were studied and compared with those synthesized previously from oligomeric chitosan and water soluble chitosan. [ABSTRACT FROM AUTHOR]

In organic field‐effect transistors (OFETs) using disordered organic semiconductors, interface traps that hinder efficient charge transport, stability, and device performance are inevitable. Benchmark poly(9,9‐dioctylfuorene‐co‐bithiophene) (F8T2) liquid‐crystalline polymer semiconductor has been extensively investigated for organic electronic devices due to its promising combination of charge transport and light emission properties. This study demonstrates that high‐capacitance single‐layered ionic polyurethane (PU) dielectrics enable enhanced charge transport in F8T2 OFETs. The ionic PU dielectrics are composed of a mild blending of PU ionogel and PU solution, thereby forming a solid‐state film with robust interfacial characteristics with semiconductor layer and gate electrode in OFETs and measuring high capacitance values above 10 µF cm−2 owing to the combined dipole polarization and electric double layer formation. The optimized fabricated ionic PU‐gated OFETs exhibit a low‐voltage operation at −3 V with a remarkable hole mobility of over 5 cm2 V–1 s–1 (average = 2.50 ± 1.18 cm2 V–1 s–1), which is the highest mobility achieved so far for liquid‐crystalline F8T2 OFETs. This device also provides excellent bias‐stable characteristics in ambient air, exhibiting a negligible threshold voltage shift of −0.03 V in the transfer curves after extended bias stress, with a reduced trap density. [ABSTRACT FROM AUTHOR]

ZnO is considered to be a good catalyst for the synthesis of polyurethanes (PUs) by alcoholysis of bisureas (BUs). ZnO tends to form Zn(NCO)2(NH3)2 in the presence of urea at high temperature, so does it in the alcoholysis of BUs. Here, attempt is made to understand the role Zn(NCO)2(NH3)2 plays in the alcoholysis of BUs. A loading of Zn(NCO)2(NH3)2 at 5 mol% is found to be sufficient to catalyze the polymerization and the reaction time is greatly cut from 40 h (catalyzed by ZnO) to 26 h, with similar chemical structures and properties. The tensile strength, elongation at break, and toughness for PU–Zn‐5 can reach 43.8 MPa, 330%, and 94.0 J cm−3, respectively. One‐pot synthetic strategy is then further introduced to improve the efficiency of the polymerization. Zn(NCO)2(NH3)2, BU, and PU can be synthesized in one‐pot, by adding ZnO, urea, diamine, LiBr, and diol sequentially. The feasibility of this one‐pot method is verified, indicated by the similar reaction time, chemical structures, molecular weight, thermal and mechanical properties. This one‐pot synthetic strategy offers an efficient way to synthesize PUs directly and simply from urea, diamines, and diols, which is beneficial for improving the molecular diversity of PUs. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is a traditional chemical known for its chemical stability and mechanical performance. Inspired by the similarity between the formation and breakage of chemical coordination bonds and the energy storage and release of muscle fibers, muscle‐like electrostatically spun fibers with acid‐responsive energy storage and release were prepared by introducing bio‐inspired elastic energy storage groups and bio‐active degradation groups (PU‐BPY‐Fe) in the main chain of PU, taking advantage of the good mechanical properties of PU. The fabricated electrospinning film PU‐BPY‐Fe can respond to external stimulation, which generated high strain (32 MPa), stretch of 206%, outperforming the nanofiber membrane before stimulation, similar and even higher than the biological muscles. The variable mechanical properties and elastic energy storage capacity of PU‐BPY‐Fe were attributed to the reversible hydrogen bonding and the destabilization of metal coordination bonds (Fe3+ to Fe2+) within the material under acidic stimulation. Cytotoxicity testing of the synthesized fibers indicated a degree of biocompatibility, suggesting potential for in vivo applications. This method of storing and releasing elastic energy was demonstrated and has endowed the PU‐BPY‐Fe with stimuli‐responsibility and muscle‐like mechanical properties, which may inspire the design of soft muscles materials for robots and tissue engineering applications. [ABSTRACT FROM AUTHOR]

Amorphous polymer/crystalline polymer blends can be prepared via the simultaneous polymerization of polymethacrylate/polyurethane combinations. The relationship between higher order structures and fracture mechanisms in these blends must be uncovered to elucidate the source of the increased fracture toughness of such materials. The present work involves the production of blended polymethacrylate/polyurethane and assess the internal structures of these specimens using optical and electron microscopy. These observations reveal the presence of both spherulites and elastomeric phases. The spherulites consisting of the polyurethane and are several micrometers in diameter whereas the phase‐separated polyurethane elastomeric domains are approximately 100 nm in size. Multiple cracks, crack bridging and plastic deformation around the precrack tips of loaded specimens are evidently responsible for the increased toughness of these blends. The former two phenomena are attributed to the presence of spherulites while the plastic deformation of the methacrylate matrix is ascribed to cavitation of the polyurethane elastomeric phases in response to loading. [ABSTRACT FROM AUTHOR]

In this work, a modified polyurethane adhesive (PUA) was prepared to realize a convenient encapsulation strategy for lead sedimentation and attachable perovskite solar cells (A‐PSCs). The modified PUA can completely self‐heal within 45 min at room temperature with an efficient lead ion‐blocking rate of 99.3%. The PUA film can be coated on a metal electrode with slight efficiency improvement from 23.96% to 24.15%. The thermal stability at 65 °C and the humidity stability at 55% relative humidity (RH) are superior to the devices encapsulated with polyisobutylene. The PUA film has strong adhesion to the flexible substrate and the initial efficiency of the flexible perovskite module (17.2%) encapsulated by PUA remains 92.6% within 1825 h. These results suggest that PUA encapsulation is universal for rigid and flexible PSCs with enhanced stability and low lead hazards. Moreover, it was found that flexible PSCs can be well attached to various substrates with PUA, providing a facile route for the A‐PSCs in various scenarios without additional encapsulation and installation. [ABSTRACT FROM AUTHOR]

On account of some special advantages of interpenetrating polymer networks (IPNs), the preparation of IPNs with excellent properties may be a promising way to strengthen the polyurethanes (PUs) and toughen the glycidyl azide polymer (GAP) based polytriazoles (PTAs). This work provides the effect of composition and number average molecular weight (Mn) of GAP on the mechanical properties and morphology of full‐IPNs. A series of IPNs based on the crosslinked Ace‐terminated GAP (Ace‐GAP) as polytriazole phase and crosslinked hydroxy‐terminated liquid fluorinated polymer (HTLF‐1500) as polyurethane phase (namely, GAP‐HTLF‐X full‐IPNs) were successfully fabricated via in situ polymerization without any catalysts at 80°C by azide–alkynyl click chemistry and hydroxyl‐isocyanate urethane reaction. These IPNs were characterized using attenuated total reflectance/Fourier‐transform infrared spectroscopy (ATR/FTIR), uniaxial tensile testing, swelling measurement, and scanning electron microscopy (SEM). The tensile strength of GAP‐HTLF full‐IPNs gradually increased by increasing the weight ratio of Ace‐GAP, but the breaking elongation dramatically decreased compared with elongation at break of HTLF polyurethane. In addition, a small Mn of GAP is beneficial in enhancing the tensile strength, elongation at break and toughness of the IPNs. However, a small Mn of GAP corresponds to increased difficulty of preparing GAP‐HTLF full‐IPNs. GAP1k‐HTLF full‐IPN was not successfully prepared. When the Mn of GAP was 2000 g/mol, the GAP2k‐HTLF‐80 full‐IPN exhibited prominent mechanical performance with a tensile strength of 83.1 MPa, elongation at break of 28.5% and fracture energy of 99.1 kJ/m3. Swelling measurement showed that when the weight ratio of GAP with larger Mn (5, 3, and 2 k) increased to more than 70%, the molecular interpenetration existed in the IPNs, demonstrating the presence of additional physical crosslinks and entanglement for full‐IPNs. SEM studies revealed that highly formed interpenetration and few microphase separations can be observed on the fracture surface of the IPNs with optimal mechanical properties. Combined with the results of mechanical properties, swelling measurement, and SEM studies, the degree of molecular interpenetration and microphase separation were beneficial to improve the mechanical properties of elastomers. This work can provide a certain guiding significance for the preparation of IPN with excellent properties. [ABSTRACT FROM AUTHOR]

Underwater adhesives with injectable, organic solvent‐free, strong, fast adhesion, and hemostatic properties have become an urgent need in biomedical field. Herein, a novel polyurethane underwater adhesive (PUWA) inspired by mussels is developed utilizing the rapid post‐cure reaction of isocyanate esterification without organic solvents. The PUWA is created through the injectable two component curing process of component A (biocompatible polyurethane prepolymer) and component B (dopamine modified lysine derivatives: chain extender‐LDA and crosslinker‐L3DA). The two‐component adhesive cures quickly and firmly underwater, with an impressive bonding strength of 40 kPa on pork skin and excellent burst pressure of 394 mmHg. Moreover, the PUWA exhibits robust adhesion strength in hostile environments with acid, alkali and saline solutions. Combined with excellent biocompatibility and hemostatic performance, the PUWA demonstrates effectively sealing wounds and promoting healing. With the ability to bond diverse substrates rapidly and strongly, the PUWA holds significant potential for application in both biomedical and industrial fields. [ABSTRACT FROM AUTHOR]

Solid‐state lithium metal batteries (SSLMBs) have gained extensive attraction as one kind of next‐generation energy storage device. However, the drawbacks of flammability, low mechanical strength, and low ionic conductivity limit the further development of solid‐state polymer electrolytes (SPEs). In this work, a reactive flame‐retardant unit into the polymer framework via covalent bonding to create a nonflammable and stretchable polyurethane‐based SPEs is introduced. Meanwhile, the mechanical strength of the polymer backbone is increased by grafting a rigid benzene ring unit, which remarkably suppresses the lithium‐dendrite growth. As a result, these inflammable SPEs do not burn after contact with flames for 6 s. Furthermore, the obtained SPE expands the electrochemical stability window up to 5.1 V. Small monomers containing bromine decompose on the surface of lithium metal creating a LiBr riched solid electrolyte interface (SEI). Li|SPEs|Li symmetric battery offers a stable cycling life for more than 2100 h at 0.2 mA cm−2 and 0.2 mAh cm−2. The LiNi0.6Co0.2Mn0.2O2|SPEs|Li cell equipped with the integrated cathode delivers a 142.1 mAh g−1 capacity after 330 cycles at 0.3 C with 85.2% capacity retention. [ABSTRACT FROM AUTHOR]

The packing of hard segment in polyurethane hard domain has not been resolved or seen clearly yet. In this work, we prepared polyurethane blends, which were composed of different weight ratios of crystallizable 1195A and non‐crystallizable EG85A, to study the structural evolution and crystallization in mixed hard domain. Time and temperature dependent differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), and x‐ray diffraction results were used to record the micro‐phase evolution and crystallization processes. It was very surprising to find that the multiple melting temperatures in these blends were similar. We deduced that the packing of hard segment tended to separate into different groups, probably dependent on their segmental length. The crystalline nucleus was consist of 1195A hard segments with similar length, and the out‐layer structure was consisted of mixed hard segments of varying lengths. The FTIR results demonstrated that crystallinity did not affect the degree of hydrogen bonding association (HBA), and the stacking of hard segments may be only differed in the degree of ordering. Moreover, the degree of HBA of the blends was always higher than the calculated number based on weight ratio of pure samples. [ABSTRACT FROM AUTHOR]

This review systematically summarizes the repair mechanisms and applications of self‐healing polyurethane (SHPU) materials aiming at energy conservation and safety under different repair methods. As of now, the repair methods that have emerged can be divided into two categories: substance landfill and bond repair. In terms of the repair mechanisms for both, the former involves the release of healing agents from micro‐carriers (microcapsules, hollow fibers, and microvascular) to fill the damaged area upon external impact. In contrast, bond repair combines physical and chemical changes triggered by light, heat, and other factors. To achieve efficient self‐healing in this mode, both the reorganization of broken chemical bonds and the high mobility of chain segments are crucial. Reversible covalent bonds and supramolecular interactions, as two branches of aforementioned reversible chemical bonds, share the responsibility for maintaining efficient self‐healing despite infinite cycling. Additionally, multiple synergistic crosslinked networks, special nanomaterials, and microphase separation are often used to solve the problem of incompatible healing efficiency and mechanical strength in bond repair. When the perspective is focused on the application, this gradually improved SHPU with strong potential and comprehensive performance has provided raw materials for many fields related to human development, such as road, architecture, healthcare, and electronic. [ABSTRACT FROM AUTHOR]

Continuous development in the formulation and processing techniques of polyurethane (PU) coatings improves an aesthetic appearance as well as protection against environmental factors. In this study, the formulation of PU coating with polyethylene glycol 600 (PEG600), isophorone diisocyanate (IPDI), and trimethoxysilylpropylcarbamoyloxyhexane (TMSCH) silane‐based additive is optimized to obtain high scratch‐resistant coating. An addition of 43.1 wt.% TMSCH in PU formulation resulted in a significant improvement in the scratch resistance and wettability properties compared with pure PU film. The homogenously prepared micron‐thick coatings are characterized using scanning electron microscopy analysis and Fourier transform infrared spectroscopy. The results confirm the presence of silane additives in the PU coating matrix. The mechanical properties improved due to the increased crosslinking networks via the formation of urethane bonds by increasing the TMSCH in PU formulation. Prepared PU coating showed combined features of transparency, hydrophobicity, scratch resistance, and mechanical strength that make it a promising candidate for household appliances. [ABSTRACT FROM AUTHOR]