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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]

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]

With the booming development of communication technology and electronic devices, increasingly complex real-world scenarios propose higher demands on electromagnetic interference (EMI) shielding materials. Wearable EMI shielding materials with Joule heating capability and human motion detection can effectively promote benign functioning of the human body and protect sensitive electronic devices in cold and harsh environments. In this paper, silver nanowires (AgNWs)/polyurethane (PU) composite foams with multicellular structures were prepared by a simple dip-drying method. Benefiting from the high conductivity (10,417 S m–1) of the ultralong AgNW network and the interfacial polarization between the silver nanoparticles and the AgNWs, the composite foams have a high EMI shielding performance dominated by microwave absorption. The EMI shielding effectiveness (SE) and specific EMI shielding effectiveness (SSE/t) of the composite foam in the X-band (8.2–12.4 GHz) reached 94.96 dB and 9,169.8 dB cm2 g–1, respectively. The electromagnetic shielding effectiveness is up to 99.99999997%. Meanwhile, at an external voltage of 0.75 V, the surface saturation temperature of the IAgNWs–5/PU composite foam rapidly increased from room temperature to 125.6 °C and remained steady. Furthermore, the IAgNWs–5/PU composite foam can be used as a multifunctional sensing device for monitoring human motion signals based on the good resilience of the PU foam and the stability of the AgNW conductive network. These superior properties make the AgNWs/PU composite foam have great potential applications in military equipment, aerospace, and wearable electronic devices. [ABSTRACT FROM AUTHOR]

High fracture toughness at cryogenic temperature and radiation hardness can be conflicting requirements for the resins for the impregnation of superconducting magnet coils. The fracture toughness of different epoxy-resin systems at room temperature (RT) and at 77 K was measured, and their toughness was compared with that determined for a polyurethane, polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Among the epoxy resins tested in this study, the MY750 system has the highest 77 K fracture toughness of KIC = 4.6 MPa√m, which is comparable to the KIC of PMMA, which also exhibits linear elastic behaviour and unstable crack propagation. The polyurethane system tested has a much higher 77 K toughness than the epoxy resins, approaching the toughness of PC, which is known as one of the toughest polymer materials. CTD101K is the least performing in terms of fracture toughness. Despite this, it is used for the impregnation of large Nb3Sn coils for its good processing capabilities and relatively high radiation resistance. In this study, the fracture toughness of CTD101K was improved by adding the polyglycol flexibiliser Araldite DY040 as a fourth component. The different epoxy-resin systems were exposed to proton and gamma doses up to 38 MGy, and it was found that adding the DY040 flexibiliser to the CTD101K system did not significantly change the irradiation-induced ageing behaviour. The viscosity evolution of the uncured resin mix is not significantly changed when adding the DY040 flexibiliser, and at the processing temperature of 60 °C, the viscosity remains below 200 cP for more than 24 h. Therefore, the new resin referred to as POLAB Mix is now used for the impregnation of superconducting magnet coils. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is a versatile polymer with many applications in a wide range of products. A novel 3D printing technology called liquid additive manufacturing (LAM) extended its possibilities by generating PU elastomers with gradient properties in continuous processing. LAM, being a relatively new technique, has not been extensively researched, particularly in terms of the curing behavior of the liquid resin. In this work, we investigated the effect of composition on gelation time tGP as measured by time-resolved mechanical spectroscopy (TRMS) and analyzed using the Winter–Chambon criterion with the assistance of the IRIS software. This method is more accurate than the previous approach, which involved time sweeps with a constant frequency. It was found that the gel time tGP first decreased and then increased with increasing polyol ratio, ranging from 231 to 378 min. Furthermore, the crosslink densities of the different PU elastomers measured from the rheological and tensile tests were calculated and compared based on the theory of rubber elasticity. The crosslink density decreased with an increasing polyol ratio in both methods. However, the crosslink density values obtained from the rheological measurements were higher than those from the tensile tests. These findings demonstrate that adjusting the polyol ratio is an effective means of achieving gradient properties. The composition effects we measured offer valuable insights for the design of LAM–PU elastomers. [ABSTRACT FROM AUTHOR]

The hierarchical carbonaceous nanofillers viz. carboxylated multiwalled carbon nanotube (MWCNT-COOH as 1D), hydroxylated few-layer graphene (FLG-OH as 2D), and hybrid 3D i.e., MWCNT-COOH immobilized into FLG-OH were dispersed into segmented thermoplastic polyurethane (TPU) by twin-screw extrusion (TSE). The concentration of nanofillers was varied as 0.25, 0.5, 1.0, 2.0 and 5 wt%. To increase the level of dispersion, hybrid 3D nanofillers were also incorporated into TPU by producing cellular structures through supramolecular self-assembly route (SSAR). The cellular structure in which the nanofillers were found to be uniformly dispersed was then compounded by TSE technique. The large-scale uniform dispersion was observed at higher loading (2 wt%) by SSAR followed by TSE when compared with direct TSE. Uniform dispersion was found at 1 wt% loading by direct TSE. PU nanocomposite film reinforced with 2 wt% hybrid 3D nanofillers showed good gas barrier property with ~63% reduction of helium gas permeability to 472 cm3/m2/day from 1287 cm3/m2/day of neat PU film. [ABSTRACT FROM AUTHOR]

In this study, the effect of temperature (below and above Tg) on the rate of crack growth and on the fatigue threshold energy release rate of a polyurethane (PU) adhesive is analysed. The effect on the results of the Paris law relation used is also investigated. Tests were performed under a displacement-control strategy and at different temperatures. Out of the experimental data, the threshold energy release rate was determined as a function of temperature, something which up until now has been much more common for adhesive systems other than polyurethane. Results showed that the threshold energy release rate diminishes with increasing temperature, while the crack growth rate increases for a given strain energy release rate. The ratio between the threshold energy release rate and critical strain energy release rate remained constant for tests above the Tg, indicating that fatigue tests need only be performed at one temperature when above the Tg at least for the range of temperatures considered in this study and for the adhesive tested. A Paris law relation taking into account the effect of R-ratio during the displacement-control fatigue tests proved effective in unifying results at different temperatures. [ABSTRACT FROM AUTHOR]

Seamless expansion joints for small- and medium-span bridges attract engineers due to their acknowledged integrity (durability), driving comfort and noise attenuation. Traditional asphalt plugin joints are easy and cheap to install, but they are hindered by premature failures frequently observed in situ. Comparatively, polyurethane (PU) possesses good durability and toughness and excellent chemical resistance, etc. The purpose of this study is to identify the proper PU material and devise a new seamless expansion joint. As such, the mechanical properties of three PU materials were tested, including initial setting time, tensile strength, rupture strain, hardness, wheel rutting, adhesion to pavement, water absorption, and aging. The appropriate mass ratio was identified to be polyol/isocyanate = 100/105. Subsequently, monotonic tensile/compressive, vertical loading and low-cycle fatigue tests were performed on the four full-scale expansion joints. It revealed that the rate-dependent behavior rendered the PU material suitable for seamless joints, as it was softer to accommodate the low-rate longitudinal deformation and was stiffer to sustain the high-rate vehicle loadings. Furthermore, the inclined angle between the PU and pavement would ameliorate the strain status and is recommended for practical use. Experimental and numerical results were synthesized into a proposed alternative polyurethane-based design that reduces the vertical displacement and circumvents the possible early failures under the effect of dynamic traffic loading. [ABSTRACT FROM AUTHOR]

In this study cinnamaldehyde (CA) doped polyurethane cholesteryl pelargonate cholesteric liquid crystal composite membranes were produced and their properties were examined for use in biological applications. The relationship between the blood coagulation and protein adsorption was studied and the results showed that increasing CA concentration allowed an improvement in biological properties of them. Additionally, the effect of CA on the hyrophobicity of these membranes was investigated by determining water holding capacity, contact angles. The mechanical strength of these membranes were determined and it was found that their strength increased and the ability to elongate decreased with an increasing CA dopant concentration. [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]

With the rapid development of urbanization and industrialization, air pollution is increasingly harmful to life on earth. At present, purifying polluted air through functional filter materials is an effective but still challenging and important strategy. But there was the problem that the air filter protection materials are easy to get wet, which will reduce the filtering effect and cause the service life to decrease. In this study, we used PU fiber membrane prepared with electrospinning as the substrate, fluorinated silica nanoparticles (F-SNs) and quaternary ammonium salt silica particles (Q-SNs) were used as functional particles, PDMS were used as adhesive to prepare hydrophobic and anti-fouling F/Q-SNs-PU fiber membrane through coating. F/Q-SNs-PU fiber membrane exhibited excellent hydrophobic stability, excellent anti-fouling and self-cleaning ability, and filtration effect. Therefore, F/Q-SNs-PU fiber membrane can effectively alleviate the air filtration problem in high humidity environment by virtue of its excellent hydrophobic anti-fouling performance and filtering effect. [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]

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]

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]

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]

Non-isocyanate polyurethane synthesis by non-Sn catalysis is an essential challenge toward green polyurethane synthesis. Bismuth compounds are attractive candidates due to their low cost, low toxicity, and availability to urethane chemistry. This work applied various Bi catalysts to the self-polycondensation of a bishydroxyurethane monomer and found BiCl3 to be an excellent catalyst through optimization. The catalytic activity and price of BiCl3 are comparable to those of Bu2SnO, while its toxicity is significantly low. BiCl3 is, therefore, a promising alternative to Sn-based catalysts in non-isocyanate polyurethane synthesis. [ABSTRACT FROM AUTHOR]

The entanglement of fibers can form physical and topological structures, with the resulting bending and stretching strains causing localized changes in pressure. In this study, a multi-layer polyurethane-fiber-prepared (MPF) sensor was developed by coating the CNT/PU sensing layer on the outside of an elastic electrode through a wet-film method. The entangled topology of two MPFs was utilized to convert the stretching strain into localized pressure at the contact area, enabling the perception of stretching strain. The influence of coating mechanical properties and surface structure on strain sensing performance was investigated. A force regulator was introduced to regulate the mechanical properties of the entangled topology of MPF. By modifying the thickness and length proportion of the force regulator, the sensitivity factor and sensitivity range of the sensor could be controlled, achieving a high sensitivity factor of up to 127.74 and a sensitivity range of up to 58%. Eight sensors were integrated into a sensor array and integrated into a dance costume, successfully monitoring the multi-axis motion of the dancer's lumbar spine. This provides a new approach for wearable biomechanical sensors. [ABSTRACT FROM AUTHOR]

This pilot investigation identifies the influence that changing the process variables of curing pressure, curing temperature, and mix ratio of a polyurethane/agglomerated cork matrix has on the mechanical properties of energy absorption, Young's modulus of elasticity, and spring stiffness in safety helmets intended for micro-transport riders. The results are compared to expanded polystyrene, a material commonly used in micro-transport helmets. Mechanical testing of the various samples found that, over the range tested, curing pressure had no effect on any of the mechanical properties, while increasing amounts of resin caused a stiffer structure, and increasing curing temperature led to increased energy absorption. Consistent with the elastic modulus findings, all polyurethane/agglomerated cork test samples demonstrated higher median levels of spring stiffness, ranging from 7.1% to 61.9% greater than those found for expanded polystyrene. The sample mixed at a 1.5:1 binder/cork ratio and cured at 40 °C displayed the closest spring stiffness to EPS. While the mechanical properties of the eco-friendly polyurethane/agglomerated cork matrix did not match those of expanded polystyrene, the difference in performance found in this study is promising. Further investigation into process variables could characterise this more ecologically based matrix with equivalent energy-absorbing and structural characteristics, making it equivalent to currently used expanded polystyrene and suitable for use in micro-transport helmets. [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]

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]

Polyurethane foams are well-known optimal thermal-insulating materials, which have good thermal insulation performance, high strength, and lightweight properties. Here, we describe a chlorine-free and fluorine-free polyurethane chemical foaming agent (CFA-1) that can react with isocyanate to release CO2 gas and foam polyurethane. We systematically studied its application performance in the field of polyurethane spraying by substituting the current most advanced and environment-friendly physical foaming agent 1-chloro-3,3,3-trifluoroprop-1-ene in different proportions. The results show that highly competitive mechanical properties lead to economical, environment-friendly, and efficient features. The lower thermal conductivity, more compact and smaller bubble structure, and excellent compression strength were achieved by tuning the proportion of CFA-1 from 20% to 60%. Thus, a promising material system was established for the development of the rigid polyurethane foam industry. [ABSTRACT FROM AUTHOR]

Plastic degradation by biological systems emerges as a prospective avenue for addressing the pressing global concern of plastic waste accumulation. The intricate chemical compositions and diverse structural facets inherent to polyurethanes (PU) substantially increase the complexity associated with PU waste management. Despite the extensive research endeavors spanning over decades, most known enzymes exhibit a propensity for hydrolyzing waterborne PU dispersion (i.e., the commercial Impranil DLN-SD), with only a limited capacity for the degradation of bulky PU materials. Here, we report a novel cutinase (CpCut1) derived from Cladosporium sp. P7, which demonstrates remarkable efficiency in the degrading of various polyester-PU materials. After 12-h incubation at 55°C, CpCut1 was capable of degrading 40.5% and 20.6% of thermoplastic PU film and post-consumer foam, respectively, while achieving complete depolymerization of Impranil DLN-SD. Further analysis of the degradation intermediates suggested that the activity of CpCut1 primarily targeted the ester bonds within the PU soft segments. The versatile performance of CpCut1 against a spectrum of polyester-PU materials positions it as a promising candidate for the bio-recycling of waste plastics. IMPORTANCE Polyurethane (PU) has a complex chemical composition that frequently incorporates a variety of additives, which poses significant obstacles to biodegradability and recyclability. Recent advances have unveiled microbial degradation and enzymatic depolymerization as promising waste PU disposal strategies. In this study, we ident ified a gene encoding a cutinase from the PU-degrading fungus Cladosporium sp. P7, which allowed the expression, purification, and characterization of the recombinant enzyme CpCut1. Furthermore, this study identified the products derived from the CpCut1 catalyzed PU degradation and proposed its underlying mechanism. These findings highlight the potential of this newly discovered fungal cutinase as a remarkably efficient tool in the degradation of PU materials. [ABSTRACT FROM AUTHOR]

Protein-stable coverage of the artificial implant is a key problem for biocompatibility. In the present study, a protein layer was attached covalently to a polyurethane surface treated by an ion beam. A plasma system consisting of a vacuum chamber (0.8 Pa pressure) with a high voltage electrode powered by a short pulse (20 μS pulse duration and 200 Hz pulse repetition) generator was designed. Polyurethane with a formulation certified as a material for medical implants was treated by nitrogen ions with an energy of 20 keV and 5 × 1014–1016 ions/cm2 fluence range. Wettability measurements, X-ray photoelectron, Raman, Fourier transform infrared attenuated total reflection, and ellipsometry spectra showed a significant change in the structure of the surface layer of the treated polyurethane. The surface of the treated polyurethane contained a carbonised layer containing condensed aromatic clusters with terminal free radicals. The surface energy of polyurethane surface increased from 33 to 65 mJ/m2. The treated polyurethane surface became capable of adsorbing and chemically binding protein (fibrinogen). The designed system for ion beam treatment can be used for surface activation of biomedical polymer devices, where a total protein coverage is required. [ABSTRACT FROM AUTHOR]

Catalysts are often employed to enable nonisothermal reaction kinetic studies when tracking cure progression of polyurethane reactions. However, when quickly reacting, catalyzed materials are prepared through mixing followed by the addition of fillers or additives, subsequent processing of the partially reacted material becomes difficult. Here, chemorheology is used to track changes in viscoelastic properties of uncatalyzed polybutadiene‐diisocyanate reactions for multiple days, which quantifies the degree of cure during polymerization. Viscosity profiles are accurately captured by the two‐stage Arrhenius model (r2>0.95), and conversion progress is adequately represented by the Kamal–Sourour model (r2>0.76). Transition state analysis via Wynne–Jones–Eyring–Evans theory (WJEE) reveals the presence of an associative mechanism according to entropic and enthalpic activation energies ΔS# = −96.9 J K−1 and ΔH# = 36.4 kJ, respectively. These rheokinetic modeling results align with Fourier transform infrared spectroscopy findings. To the knowledge, no rheokinetic studies have tracked cure progress of this uncatalyzed system for the extended timeframe presented here. The cure profile also presents unique viscosity growth, representative of molecular weight buildup, compared to catalyzed systems. This finding emphasizes the novelty of applying previously developed chemorheological models to multiday thermosetting reactions within a flow field in a manner that is generalizable to many long‐term curing systems. [ABSTRACT FROM AUTHOR]

With the increasing awareness of marine ecological environment, biocide-free marine antifouling coatings have been gaining increased attention in the field of marine antifouling. Among all the antifouling approaches, constructing fouling-release coatings (FRCs) may be the most effective and economical way caused by the biocide-free. However, the low mechanical strength, weak adhesion to substrates, and poor static fouling resistance of traditional silicone-based FRCs, which limiting their applications. In this work, we synthesized a polyurethane with hydroxyl terminated polydimethylsiloxane (PDMS), polytetrahydrofuran (PTMG) and isophorone diisocyanate (IPDI) as main chains, 2,2'-Bis (hydroxymethyl)butyric acid (DMBA) as chain extender, and γ-aminopropyl triethoxysilane (KH-550) as crosslinker by condensation polymerization. Meanwhile, Triclosan (TCS) was used as an antibacterial agent and mixed into the polymer system with uniformly dispersed. We introduced urethane groups into silicone, which improved the mechanical strength (ultimate tensile strength: 1.379 MPa, elongation at break: 282%). As a result, the laboratory bioassays using bacteria (E. coli, and S. aureus) showed that the anti-bacterial efficiency could respectively reach ∼95% and ∼93%, which demonstrated an outstanding antifouling property of the D:K = 0.7:1.3/1.0. This work overcomes the low strength issue of traditional fouling-release coatings and provides a simple strategy for silicone-based polyurethane antifouling coatings. [ABSTRACT FROM AUTHOR]

Fluorinated polyurethane (FPU) is a new kind of polyurethane (PU) material with great applicational potential, which is attributed to its high bond energy C-F bonds. Its unique low surface energy, excellent thermal stability, and chemical stability have attracted considerable research attention. FPU with targeted performance can be precisely synthesized through designing fluorochemicals as hard segments, soft segments, or additives and changes to the production process to satisfy the needs of coatings, clothing textiles, and the aerospace and biomedical industries for materials that are hydrophobic and that are resistant to weathering, heat, and flames and that have good biocompatibility. Here, the synthesis, structure, properties, and applications of FPU are comprehensively reviewed. The aims of this research are to shed light on the design scheme, synthesis method, structure, and properties of FPU synthesized from different kinds of fluorochemicals and their applications in different fields and the prospects for the future development of FPU. [ABSTRACT FROM AUTHOR]

Conventional paint spraying processes often use small molecule organic solvents and emit a large amount of volatile organic compounds (VOCs) that are highly toxic, flammable, and explosive. Alternatively, the spraying technology using supercritical CO2 (scCO2) as a solvent has attracted attention because of its ability to reduce VOC emissions, but the flow characteristics of coatings have not been thoroughly studied. Therefore, we numerically simulate the spraying process based on the actual process of scCO2 spraying polyurethane coatings by computational fluid dynamics (CFD). The effects of inlet pressure and volume fraction of scCO2 on the fluid motion parameters inside the nozzle as well as the atomization effect of droplets outside the nozzle are investigated. The simulated results show that a fluid with a large volume fraction of scCO2 will obtain a smaller density, resulting in a larger velocity and a larger distance for the spray to effectively spray. Higher coating content and bigger inlet pressures will result in higher discrete phase model (DPM) concentrations, and thus a bigger inlet pressure should be used to make the droplets more uniform across the 30° spray range. This study can provide theoretical guidance for the process of scCO2-sprayed polyurethane resin. [ABSTRACT FROM AUTHOR]

Two polyurethanes (PUs) were similarly synthesized by reacting a cycloaliphatic isocyanate with 1,4-butanediol and two polyols of different nature (polyester, polycarbonate diol) with molecular weights of 1000 Da. Only the PU synthesized with polycarbonate diol polyol (YCD) showed intrinsic self-healing at 20 °C. For assessing the mechanism of intrinsic self-healing of YCD, a structural characterization by molecular weights determination, infrared and X-ray photoelectronic spectroscopies, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis, and dynamic mechanical thermal analysis was carried out. The experimental evidence concluded that the self-healing at 20 °C of YCD was due to dynamic non-covalent exchange interactions among the polycarbonate soft segments. Therefore, the chemical nature of the polyol played a key role in developing PUs with intrinsic self-healing at 20 °C. [ABSTRACT FROM AUTHOR]

The availability of carbon nanotube (CNT)-based polymer composites allows the development of surface-attached self-sensing crack sensors for the structural health monitoring of reinforced concrete (RC) structures. These sensors are fabricated by integrating CNTs as conductive fillers into polymer matrices such as polyurethane (PU) and can be applied by coating on RC structures before the composite hardens. The principle of crack detection is based on the electrical change characteristics of the CNT-based polymer composites when subjected to a tensile load. In this study, the electrical conductivity and electro-mechanical/environmental characterization of smart skin fabricated with various CNT concentrations were investigated. This was performed to derive the tensile strain sensitivity of the smart skin according to different CNT contents and to verify their environmental impact. The optimal CNT concentration for the crack detection sensor was determined to be 5 wt% CNT. The smart skin was applied to an RC structure to validate its effectiveness as a crack detection sensor. It successfully detected and monitored crack formation and growth in the structure. During repeated cycles of crack width variations, the smart skin also demonstrated excellent reproducibility and electrical stability in response to the progressive occurrence of cracks, thereby reinforcing the reliability of the crack detection sensor. Overall, the presented results describe the crack detection characteristics of smart skin and demonstrate its potential as a structural health monitoring (SHM) sensor. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) are versatile polymers used in industries at large scale. PUs are in used in the form of foam, elastomers, adhesives, fibers, thermosets, thermoplastics, etc. Polyols and isocyanates are the two compounds used to synthesize PU. Day by day increasing price of crude oil and its destructive impact on the environment motivate researchers to develop bio‐PU. Seed oils are attracting nowadays because of their renewability and low cost. They are the best substitutes for fossil fuel‐based polyol used in the preparation of PUs. However, these bio‐based PUs show lower thermal, mechanical properties, which needs improvement to further their utilization. The need to maintain a cleaner environment for the survival of both aquatic and terrestrial lives including human beings is very crucial and is a subject of increasing concern to the environmentalists. The removal of heavy metals, dyes, and organic pollutants from wastewater before their discharge in the environmental is very important due to its polluting effect on the underground water. This review article emphasizes on to provide insight on the developments in the field of chemistry, types, and synthesis of various PUs, as well as on the components used to synthesize bio‐based PUs and water treatment applications. Additionally, details on the PU's environmental friendliness are highlighted, with a focus on their potential to recycling and recovery. This review also highlights the details of the synthesis, uses, and potential futures of PU composites. [ABSTRACT FROM AUTHOR]

Polyurethane elastomers are among the most versatile classes of industrial polymers—typically achieved through a two-step synthesis of segmented block copolymers, comprising very long and soft segments that provide elasticity and significantly long and hard segments that provide strength. The present research focused on the design of a single-step synthesis of a new segmented polyurethane consisting of very short soft and hard segments, crosslinked by preferentially side-reacted hierarchical tertiary oligo-uret network structures, thus exhibiting significant strength, elasticity, and toughness. Despite the theoretically linear structure, both FTIR and solid-state 13C NMR spectroscopy analyses indicated the quasi-equal presence of urethane groups and tertiary oligo-uret structures in the resulting polymer, indicating a preferential consecutive side reaction mechanism. Thermal analysis indicated the significant crystallization of soft segments consisting of only four ethylene oxide units, which was, hereby, demonstrated to occur via an extended chain mechanism. Tensile mechanical properties included significant strength, elasticity, and toughness. Increasing the soft segment length led to a decreased tertiary oligo-uret secondary crosslinking efficacy. The preferential hierarchical side reaction mechanism was, hereby, further confirmed through the synthesis of a completely new type of hyper-branched polymer via diisocyanate and a mono-hydroxy-terminated reagent. The structure–property relations and reaction mechanisms demonstrated in the present research can facilitate the design of new polyurethanes of enhanced performance and processing efficacy for a variety of novel applications. [ABSTRACT FROM AUTHOR]

The use and significance of adhesives in various industries are explored, highlighting the growth of the adhesive market and the crucial role of time in adhesive bonding. The composition of adhesives, particularly polyurethane adhesives (PUR), is detailed, emphasizing their sensitivity to environmental factors, like moisture and UV radiation. Various factors influencing adhesive properties, such as reactivity and curing-induced shrinkage, are discussed, along with the importance of catalysts in adjusting reaction rates. Onecomponent moisture-curable PUR adhesives are presented as versatile and continually improving alternatives in structural adhesive applications. The research's focus was to investigate the curing speed of Sikaflex-252 1-component PUR structural adhesive under different conditions, including room temperature, room temperature with ~30 % humidity, and room temperature with ~100 % humidity. [ABSTRACT FROM AUTHOR]

Polyurethane/2-hydoxyethyl methacrylate (PU/2-HEMA) hybrids with the modifying properties of unsaturated polyester resin (UPR) were prepared through two steps of polymerization. In the first step, polyurethane prepolymers (PUA) were prepared with an NCO/OH ratio of 2.2 by a polyaddition reaction based on isophorone diisocyanate (IPDI), polyoxypropylene glycol (PPG 2000), and PPG 2700. In the second step, the hybrid was prepared by adding and mixing different contents of 2-hydroxyethyl methacrylate (2-HEMA) to prepolymer polyurethane (PUA). The effect of PUA and PUA/2-HEMA hybrid on the physicomechanical properties of UPR films was studied, including viscosity, compressive strength, hardness, thixotropy, and gamma radiation resistance. The addition of PUA/2-HEMA hybrids improved the physical and mechanical properties of UPR more than the addition of PUA owing to the existence of functional groups derived from PUA and PUA/2-HEMA, such as NCO, double bonds, and NH, which can establish cross-linking between UPR and PUA, as well as between UPR and PUA/2-HEMA. The findings demonstrate that the mechanical properties improve with dose, indicating cross-linking involving the double bonds of 2-HEMA, NH, C=O, as well as the ether group over oxidative degradation. However, an increase in 2-HEMA content in PUA hybrids increases the gamma radiation resistance, tensile, and compressive strengths demonstrating that cross-linking leads over oxidative degradation. This is attributed to the formation of the polymeric network as a result of cross-linking between PUA and 2-HEMA as indicated in the experimental results shown in Table 3 and Schemes 2 and 3. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, polyurethane-polystyrene composites (RPURF-EPS) were obtained with the co-expansion method. This method consists of utilizing the heat of the exothermic reaction of polyurethane (PUR) formation to expand polystyrene beads (PSBs). The materials were obtained using polyurethane systems based on the selected blowing agents, such as cyclopentane, a mixture of fluorocarbons and water. The analysis of the foaming process was carried out using a special device called FOAMAT. The characteristic start, rise, gelation and curing times were defined. The rise profile, the reaction temperature, the pressure and the dielectric polarization were measured. The influence of selected blowing agents on the cell structure and physical–mechanical properties of reference rigid polyurethane foam (RPURF) and RPURF-EPS, such as apparent density, compressive strength and thermal conductivity, were evaluated. Based on the research, the blowing agents that have the most beneficial influence on the properties and structure of the composites and that provide the most efficient expansion of PSBs in a light porous composite were found. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyurethane/desulfurization ash (PU/DA) composites were synthesized using "one-pot method", with the incorporation of a silane coupling agent (KH550) as a "molecular bridge" to facilitate the integration of DA as hard segments into the PU molecular chain. The effects of DA content (φ) on the mechanical properties, thermal stability, and hydrophobicity of PU, both before and after the addition of KH550, were thoroughly examined. The results of microscopic mechanism analysis confirmed that KH550 chemically modified the surface of DA, facilitating its incorporation into the polyurethane molecular chain, thereby significantly enhancing the compatibility and dispersion of DA within the PU matrix. When the mass fraction of modified DA (MDA) reached 12%, the mechanical properties, thermal stability, and hydrophobicity of the composites were substantially improved, with the tensile strength reaching 14.9 MPa, and the contact angle measuring 100.6°. [ABSTRACT FROM AUTHOR]

Light‐driven actuators are widely used for smart devices such as soft robots. One of the main challenges for actuators is achieving rapid responsiveness, in addition to ensuring favorable mechanical properties. Herein, we focused on photoresponsive polyurethane (CD‐Azo‐PU) based on controlling the crystallization of the hard segments in polyurethane (PU) by complexation between azobenzene (Azo) and cyclodextrins (CDs). CD‐Azo‐PU incorporated polyurethane as the main chain and a 1:2 inclusion complex between Azo and γCD as a movable crosslink point. Upon ultraviolet light (UV, λ = 365 nm) irradiation, the photoresponsiveness of CD‐Azo‐PU bent toward the light source (defined as positive), while that of the linear Azo polyurethane (Azo‐LPU) without peracetylated γ‐cyclodextrin diol (TAcγCD‐diOH) as a movable crosslinker bent in the direction opposite the light source. The bending rates were determined to be 0.25°/s for CD‐Azo‐PU and 0.083°/s for Azo‐LPU, indicating that the bending rate for CD‐Azo‐PU was faster than that for Azo‐LPU. By incorporating movable crosslinks into CD‐Azo‐PU, we successfully achieved specific photoresponsive actuation with an enhanced rate. [ABSTRACT FROM AUTHOR]