Search Results (116)

As an emerging thermal insulation material, silica aerogel holds broad application prospects in building energy conservation. Silica aerogel based waterborne coatings are low thermal conductivity, readily applicable and environmentally friendly, offering significant advantages for improving building energy efficiency. However, the inadequate dispersibility and agglomeration tendency of silica aerogel in aqueous polymer systems adversely affect coating properties. To address this challenge, a waterborne polyurethane (WPU) coating incorporating 3-aminopropyltriethoxysilane-modified organo-bridged silica aerogel (APTES-OBSA) was developed. Integration of organic segments within organo-bridged silica aerogel (OBSA) framework enhanced compatibility of silica aerogel with organic polyurethane chains, thereby reducing aerogel agglomeration. 3-aminopropyltriethoxysilane (APTES) surface modification of OBSA introduced amino groups that strengthened interfacial interaction between OBSA-WPU, effectively enhancing aerogel dispersion within the aqueous polyurethane matrix. APTES-OBSA loading achieved 20 wt% in WPU composite coatings. Compared to neat WPU coating, the composite coatings achieved 21.6% reduction in thermal conductivity, 10 °C lower temperature under thermal irradiation, and 26.6% higher adhesion. Additionally, the composite coatings demonstrated enhanced thermal stability and good water resistance. The excellent comprehensive performance positions this material as a promising eco-friendly thermal insulation coating for building energy-saving applications. Full article

Waterborne polyurethane (WPU) coatings have gained significant attention in the industry due to their low environmental impact and excellent properties. Furthermore, the UV-curing system reduces energy costs and enhances curing efficiency. Hence, exploring the UV-curable WPU system is essential for advancing the next generation of coatings. In this study, a 2K WPU system was developed by functionalizing isocyanate-terminated polyurethane with thiol and vinyl groups. The coating was cured under UV light through a thiol-ene click reaction, and the effects of photoinitiator content on the coating performance were investigated. The feasibility of sunlight curing for this WPU coating was also assessed. The results showed that while photoinitiator content had a slight impact on UV-cured WPU coatings, it significantly affected sunlight-cured WPU. Also, with the appropriate photoinitiator content, sunlight-cured WPU could achieve comparable performance to UV-curable ones. Full article

Guided bone regeneration (GBR) membrane has proven to be a fundamental tool in the realm of bone defect repair. In this study, we develop a mussel-inspired composite biomaterial through polydopamine-assisted, combining gelatin–WPU matrix with the ion-release behavior of Cu–MSNs for augmented bone regeneration. The optimized composite membrane exhibits enhanced mechanical stability, demonstrating a tensile strength of 11.23 MPa (representing a 2.3-fold increase compared to Bio-Gide^®), coupled with significantly slower degradation kinetics that retained 73.3% structural integrity after 35-day immersion in physiological solution. Copper ions act as angiogenic agents to promote blood vessel growth and as antimicrobial agents to prevent potential infections. The combined effect of these components creates a biomimetic environment that is ideal for cell adhesion, growth, and differentiation. This research significantly contributes to the development of advanced biomaterials that combine regeneration and infection-prevention functions. It provides a versatile and effective solution for treating bone injuries and defects, offering new hope for patients in need. Full article

Regenerated cellulose (RC) films with abundant sources and low processing costs are considered to be excellent biodegradable and recycled packaging materials. However, there is still a problem to be solved: the poor strength of RC films in the wet state. Polyurethane (PU) possesses excellent mechanical properties, biocompatibility and biodegradability. In this work, a PU coating is successfully introduced on the RC film surface via a facile surface engineering strategy, followed by plane hot-pressing process, and the RC@PU films are obtained. Notably, under wet conditions, RC@PU films show outstanding mechanical properties (fracture stress of 22.5 MPa, fracture strain of 75.9%, toughness of 10.6 MJ/m³), which are greater than those of the pure RC films (18.9 MPa, 56.5%, 6.9 MJ/m³). In addition, RC@PU films play an important role in anti-water evaporation tests. Moreover, RC@PU films exhibit excellent biodegradability, which can be completely degraded in a natural environment in about 70 days. This work provides a simple and feasible surface engineering strategy for developing RC films with excellent wet strength and biodegradability. Full article

Wear resistance is the key factor that affects the long-term use of leather. Graphene has excellent wear resistance properties, but ensuring the effective dispersion of graphene in resin is crucial for determining the performance of the material. In this work, silica modified with polydopamine (SiO₂@PDA) was used as an exfoliation agent. Using the microfluidization process and water as the medium, silica-graphene hybrid nanoparticles (SiO₂@PDA-G) were prepared from expanded graphite. These nanoparticles were further compounded with waterborne polyurethane (WPU), and a superfine fiber-based fabric was used as the substrate to prepare composite coating. The results showed that the high shear force of the microfluidization process easily broke up the lamellar structure of graphite, resulting in few-layer graphene. Nano-silica was adsorbed on the surface of graphene, preventing re-aggregation between the graphene sheets. Compared to the WPU coating, the presence of SiO₂@PDA-G improved the wear resistance and mechanical properties of the coating. The wear rate and the average friction coefficient of the composite coating decreased by 48% and 69%, respectively, and the tensile strength increased by 83%. Therefore, this study provides a new strategy for improving the dispersion of graphene in polymer materials and enhancing the abrasion resistance of the coatings. Full article

This study developed bio-based waterborne polyurethane (BWPU) dispersions containing lignin as a sustainable filler with castor oil (CO), polycaprolactone diol (PCL), or poly(trimethylene ether) glycol (PO3G). The effects of the polyol structure and the presence of lignin on the mechanical performance, thermal stability, water absorption, ethanol resistance, and UV-blocking capabilities of the resulting BWPU samples were evaluated. The results revealed that lignin affects the molecular packing and interchain interactions of CO-based BWPU, thus improving its tensile strength and thermal stability while reducing its water absorption and ethanol permeability. In the PCL-based BWPU, lignin had a minimal impact on water absorption and ethanol resistance but led to greater UV-blocking ability due to interactions between the semi-crystalline matrix of PCL and the aromatic structure of the lignin. In the PO3G-based BWPU, lignin disrupted the polymer network, increasing its water absorption and reducing its ethanol resistance but significantly improving its elongation and UV-shielding behavior. These results highlight the dual role of lignin as a sustainable reinforcing agent and functional additive in enhancing the properties of BWPU. By tailoring the polyol structure and optimizing lignin use, this study demonstrates a framework for the development of eco-friendly PU composites suitable for use as coatings, barriers, UV-shielding films, and packaging Full article

Waterborne polyurethane cationomer coatings modified with 1,3-bis(3(3-(propoxy-2-ol-)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide)-3-propyloxy))tetramethyldisiloxane (TMDS–AGE–DOPA) containing phosphorus and silicon atoms were obtained. Their structures were confirmed by Fourier transform infrared (FTIR) spectroscopy. The effect of TMDS–AGE–DOPA on thermal properties, flame retardancy, and surface characteristics (gloss, contact angle, surface free energy), as well as performance properties (hardness, impact resistance), was investigated. A coupled TG-FTIR technique was employed for evolved gas analysis. Thermal stability decreased with the addition of the modifier, while the glass transition temperature increased from −19 to 25 °C. The modifier improved the flame retardancy of the material by shifting the peak temperature of the heat release rate (T_PHRR) to lower values. The gloss of the coatings was very high (>90 GU at all angles studied), although it decreased with increasing modifier content. The presence of phosphorus moieties from the modifier enhanced hydrophilicity, raising surface free energy (SFE) from 37.9 to 44.0 mJ/m². The coatings are soft materials with a Persoz hardness in the range of 0.05–0.32. The modifier increased hardness but reduced impact strength. The obtained cationomers can be applied as environmentally friendly coatings on hydrophilic surfaces such as textiles, glass, or wood. Full article

MXenes are a group of novel two-dimensional (2D) materials with merits such as large specific surface area, abundant surface-functional groups, high chemical activity, excellent mechanical properties, high hydrophilicity, and good compatibility with various polymers. In recent years, many novel high-performance organic anticorrosion coatings using MXenes as nanofillers have been reported and have attracted widespread attention. As the first successfully prepared MXene material, Ti₃C₂T_x is the most extensively studied and typical member of the MXene family. Therefore, it is taken as the representative of its family, and the status of Ti₃C₂T_x MXene/epoxy resin (EP) and MXene/waterborne polyurethane (WPU) polymer anticorrosive composite coatings is reviewed. Firstly, the structure, characteristics, and main synthesis methods of MXenes are briefly introduced. Then, the latest progress of four surface-modification strategies to improve the dispersion, compatibility, stability, and anti-aggregation properties of MXenes, namely functionalization grafting, orientation regulation, heterostructure nanocomposite design, and stabilization and greening treatment, are analyzed and summarized. Finally, the current challenges and future opportunities regarding MXene-based corrosion-resistant organic composite coatings are discussed prospectively. Full article

In this study, waterborne polyurethane (WPU), a novel modifier, was used for the wet surface modification of talc, and its mechanism was investigated. Polypropylene (PP)-based composites with modified talc were synthesized and subjected to an examination of their mechanical properties. The wetting contact angle demonstrated that the modified talc exhibited an excellent modification effect at a specific amount of modifier (2.0 wt.%). The X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) results indicated the successful coating of WPU on the surface of the talc particles. SEM images revealed that modified talc displayed improved wettability, compatibility, and dispersion in PP/talc + WPU composites. The mechanical properties results showed that the PP/talc + WPU composites ensured superior comprehensive properties with a flexural strength of 55.9 MPa, impact strength of 4.72 kJ/m², tensile strength of 34.8 MPa, and elongation of breaks of 32.4%. The incorporation of WPU-modified talc into plastic materials has been synthesized to leverage its beneficial properties, leading to reduced production costs and improved performance and functionality of the final product. Full article

Herein, we report the rational synthesis of porous g-C₃N₄ co-modified with oxygen (O) and fluorine (F) for the first time. Incorporating colloidal SiO₂ during thermal polymerization introduces lattice oxygen, forming C–O bonds, while post-treatment with NH₄·HF₂ establishes C–F bonds. The dual incorporation of O and F elements extends visible light absorption and effectively promotes the separation and transport of photoexcited charge carriers. Consequently, the co-modified g-C₃N₄ (O,F-g-C₃N₄) achieves a 13.2-fold increase in H₂ evolution rate compared to pristine g-C₃N₄. This synthesized O,F-g-C₃N₄ is then dispersed in waterborne polyurethane (WPU) to create an anti-corrosive coating for Q235 carbon steel substrates. Water resistance, mechanical property, and electrochemical characterization analyses reveal that the O,F-g-C₃N₄/WPU composite coating exhibits remarkable corrosion resistance with a high protection efficiency of 90.23%. This work offers a straightforward approach for developing highly efficient g-C₃N₄-based photocatalysts and corrosion-resistant coatings. Full article

Given the requirement of high-efficiency thermal dissipation for large-aperture space optical remote sensors, a radiator based on single-walled carbon nanotubes (SWCNTs) filled with waterborne polyurethane (SWCNTs/WPU) coatings was proposed in this work. In situ polymerized SWCNTs/WPU coatings allowed for the uniform distribution of acid-purified SWCNTs in WPU matrix. Modified oxygen-containing groups on purified SWCNTs enhanced the interfacial compatibility of SWCNTs/WPU and enabled an improved tensile strength 9 (26.3 MPa) compared to raw-SWCNTs/WPU. A high electrical conductivity of 5.16 W/mK and thermal conductivity of 10.9 S/cm were achieved by adding 49.1 wt.% of SWCNTs. Only 2.85% and 4.2% of declined ratios for electric and thermal conductivities were presented after 1000 bending cycles, demonstrating excellent durability and flexibility. The designed radiator was composed of a heat pipe, SWCNTs/WPU coatings and an aluminum honeycomb core, allowing for −1.6~0.3 °C of temperature difference for the in-orbit temperature and thermal balance experimental temperature of the collector pipe. Moreover, the close temperature difference for the in-orbit and ground temperatures of the radiator indicated that the designed radiator with high heat dissipation met the mechanical environment requirements of a rocket launch. SWCNTs/WPU would be promising electric/thermal interface materials in the application of space optical remote sensors. Full article

Eco-friendly waterborne coatings frequently exhibit poor corrosion resistance, high solvent content, and extended curing times, attributed to the excessive employment of hydrophilic groups and petroleum-derived polyols. In this work, aniline trimer (ACAT) and polyethylene glycol (PEG) were used as chain extenders. E-44 epoxy resin was subsequently utilized to modify the system and an aniline trimer-modified waterborne polyurethane (AT-WPU) dispersion was prepared and characterized. The chemical structure of the synthesized ACAT was characterized employing 1H NMR, ESI-MS, and FTIR spectroscopy. The structure and coating performance of the AT-WPU dispersion were investigated utilizing FTIR, particle size analysis, thermogravimetric analysis, DSC, TEM, SEM, and electrochemical corrosion testing. The results demonstrate that the aniline trimer-modified waterborne polyurethane dispersion was successfully synthesized. Additionally, the DSC analysis results and thermogravimetric graphs indicate that the glass transition temperature and thermal stability of the coatings increased with the addition of aniline trimer. As the aniline trimer content increased, the hardness and adhesion of the coatings were significantly enhanced. In the electrochemical corrosion assessment, the corrosion current density of AT-WPU-3 attained 7.245 × 10⁻⁹ A·cm⁻², and the corrosion rate was as low as 0.08 μm·Y⁻¹, indicating excellent corrosion resistance. The present study provides promising practical applications in the domain of metal material protection. Full article

Flexible pressure sensors based on paper have attracted considerable attention owing to their good performance, low cost, and environmental friendliness. However, effectively expanding the detection range of paper-based sensors with high sensitivities is still a challenge. Herein, we present a paper-based resistive pressure sensor with a sandwich structure consisting of two electrodes and three sensing layers. The silver nanowires were dispersed deposited on a filter paper substrate using the vacuum filtration coating method to prepare the electrode. And the sensing layer was fabricated by coating carbon nanotubes onto a mulberry paper substrate. Waterborne polyurethane was introduced in the process of preparing the sensing layers to enhance the strength of the interface between the carbon nanotubes and the mulberry paper substrate. Therefore, the designed sensor exhibits a good sensing performance by virtue of the rational structure design and proper material selection. Specifically, the rough surfaces of the sensing layers, porous conductive network of silver nanowires on the electrodes, and the multilayer stacked structure of the sensor collaboratively increase the change in the surface contact area under a pressure load, which improves the sensitivity and extends the sensing range simultaneously. Consequently, the designed sensor exhibits a high sensitivity (up to 6.26 kPa⁻¹), wide measurement range (1000 kPa), low detection limit (~1 Pa), and excellent stability (1000 cycles). All these advantages guarantee that the sensor has potential for applications in smart wearable devices and the Internet of Things. Full article

This study successfully developed a bio-based, photocurable, anionic–nonionic dual-functional chain extender, and sulfonated cardanol-based polyethylene glycol (SCP), derived from renewable resources—cardanol and polyethylene glycol—for application in waterborne polyurethane dispersions (WPUDs). Utilizing SCP as a chain extender, WPUDs were prepared through a typical acetone process with poly(butylene adipate) (PBA), isophorone diisocyanate (IPDI), and ethylene diamine (EDA) at a constant NCO/OH ratio of 1:1. This research focused on the effects of polyethylene glycol molecular weight and SCP dosage on the particle size, stability, and film-forming properties of the WPUD. Optimal dispersion stability and film-forming performance were achieved with a polyethylene glycol molecular weight of 1500 and a PBA to SCP molar ratio of 4:1, yielding a particle size of 0.326 ± 0.010 μm and excellent storage stability over six months. The resulting WPU coatings exhibited a tensile strength of 11.4 MPa, which increased to 16.8 MPa after UV irradiation owing to the formation of a semi-interpenetrating network via the photopolymerization of cardanol’s unsaturated side chains. UV cross-linking also enhanced water resistance, reducing the water absorption rate (WAR) from 18.68% to 4.21% and the water vapor transmission rate (WVTR) from 6.59 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹ to 2.26 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹, while also improving thermal stability. These findings demonstrate that SCP offers a sustainable and effective solution for developing high-performance WPU coatings. Full article

Waterborne polyurethane (WPU) often suffers from poor water resistance and mechanical properties due to hydrophilic emulsifiers. To address these issues, this study introduces glycidyl carbamate (GC) as a crosslinker to improve WPU performance. Three types of GC were synthesized using aliphatic, cycloaliphatic, and aromatic isocyanates, respectively. The crosslinked network was established through a reaction between the epoxide group of GC and the carboxylic acid and amine groups of WPU. Among these, the WPU film utilizing aromatic isocyanate-based GC exhibited the highest crosslink density, modulus, hardness, and water resistance, due to the rigidity of the aromatic molecular structure. However, the film displayed excessive brittleness, resulting in reduced tensile strength, along with yellowing typically associated with aromatic compounds. The WPU crosslinked with cycloaliphatic GC demonstrated the next best mechanical properties and water resistance, with a 2.7-fold increase in tensile strength, a 1.5-fold increase in hardness, and a 66% reduction in the water swelling ratio compared to neat WPU. This study presents a novel and effective strategy to enhance the water resistance and mechanical properties of WPU films, making them suitable for advanced coating applications. Full article