Waterborne Polyurethane Research Articles

Stress-Dissipative Elastic Waterborne Polyurethane Binders for Silicon Anodes with High Structural Integrity in Lithium-Ion Batteries

Stress-Dissipative Elastic Waterborne Polyurethane Binders for Silicon Anodes with High Structural Integrity in Lithium-Ion Batteries

Preparation and performances of cationic waterborne polyurethane coating co-modified with acrylic and amino acid

Preparation and performances of cationic waterborne polyurethane coating co-modified with acrylic and amino acid

Synthesis and application of multifunctional lignin-modified cationic waterborne polyurethane in textiles

Waterborne polyurethanes (WPUs) often have limitations like inadequate weathering resistance and thermal stability. To overcome these shortcomings, lignin has been selected as a modifier for its abundant availability, renewability, and biocompatibility. This study synthesized a cationic WPU using isophorone diisocyanate and polyethylene glycol as raw materials. Hydrophilicity was attained through the inclusion of dihydroxyethyl dodecylamine as a chain extender, while the introduction of epoxy monomers and lignin served to modify the polyurethane. Furthermore, a dye dispersion for cotton fabric dyeing was prepared by combining the synthesized polyurethane, chitosan, and dyes. The cationic nature of the polyurethane played a crucial role in facilitating dye adhesion and uptake on the fabric surface, resulting in improved dyeing performance. The incorporation of epoxy side chains and chitosan cross-linking contributed to the excellent color fastness of the dyed fabrics. Moreover, the incorporation of lignin and chitosan endowed the fabric with antibacterial properties. Simultaneously, it provided effective UV protection, characterized by a high UV protection factor value for the fabrics. This lignin-modified WPU exhibits tremendous potential in applications such as textile coatings, adhesives, and color fixation agents. It effectively addresses the limitations of traditional WPUs and offers notable advantages, including a renewable source, cost-effectiveness, and biocompatibility.

Self-matting waterborne polyurethane acrylate wood coating by 222 nm far-UVC irradiation in ambient air

Self-matting coatings, featuring micro-winkles for low gloss and a soft tactile feel, were obtained by employing 222 nm far-UVC radiation emitted by a Krypton-Chloride excimer lamp applied to UV-curable waterborne polyurethane acrylate wood coatings. The 222 nm far-UVC penetrates the wet film's top layer (a few micrometers) to induce CC to ·C−C· biradical, participating in the free radical polymerization process and resulting in the top layer completing gradient curing first. Subsequently, the thicker lower layer begins gradient curing due to the radical produced by the photoinitiator, and volume cure shrinkage induces internal stress, resulting in the formation of micro-wrinkles. This study systematically investigated the effects of varied photoinitiator concentrations (2.0 wt% and 3.0 wt%), film thicknesses (60 μm and 110 μm), and curing temperature (low: 28.3 °C, high: 37.4 °C) on the coating films' properties. At low curing temperature, the optimal matte film is characterized by gloss values of 3.6 GU at 60° and 5.6 GU at 85°. When maintaining consistent coating thickness and curing temperature, gloss values increased with higher photoinitiator concentration, while roughness values decreased. Conversely, with the same photoinitiator concentration and curing temperature, gloss values decreased as coating film thickness increased, while roughness values increased. At high curing temperature, the coating film exhibits the best matte effect with gloss values of 2.8 GU at 60° and 3.6 GU at 85°. Film gloss values experienced a slight reduction with increased film thickness or photoinitiator concentration. Scanning electron microscope observations indicated that coating films cured at high temperature displayed higher micro-wrinkles with folding than films cured at low temperature. This study demonstrates that self-matting coating films exhibit favorable physical and mechanical properties, and the curing process can occur directly in ambient air. The utilization of 222 nm far-UVC irradiation holds the potential for the large-scale production of matte coatings for wooden products.

Mechanical Stretch α-Cyclodextrin Pseudopolyrotaxane Elastomer with Reversible Phosphorescence Behavior.

Polyethylene glycol chains in two terminals of the naphthalene functional group are threaded into α-cyclodextrin cavities to form the pseudopolyrotaxane (NPR), which not only effectively induces the phosphorescence of the naphthalene functional group by the cyclodextrin macrocycle confinement, but also provides interfacial hydrogen bonding assembly function between polyhydroxy groups of cyclodextrin and waterborne polyurethane (WPU) chains to construct elastomers. The introduction of NPR endows the elastomer with enhanced mechanical properties and excellent room temperature phosphorescent(RTP) emission (phosphorescence remains in water, acid, alkali, and organic solvents, even at 160 °C high temperatures). Especially, the reversible mechanically responsive room temperature phosphorescence behavior (phosphorescence intensity increased three times under 200% strain) can be observed in the mechanical stretch and recover process, owing to strain-induced microstructural changes further inhibiting the non-radiative transition and the vibration of NPR. Therefore, changing the phosphorescence behavior of supramolecular elastomers through mechanical stretching provides a new approach for supramolecular luminescent materials.

A strong insulating, compressible Nd2O3@CNFs WPU foam for robust electromagnetic wave absorption

The portable fabrication of multifunctional, lightweight, and ultra-wide absorption bandwidth electromagnetic wave absorbing materials remains a significant challenge. In this study, both component modulation and architecture design were simultaneously employed to construct a layered porous electromagnetic wave absorbing foam (EMAF) with Nd2O3@CNFs as the backbone and waterborne polyurethane (WPU) and starch as the cross-linking agents. Due to the rich heterogeneous interfaces brought by multiple components and the electromagnetic coupling structure of Nd2O3@CNFs, EMAF-4 exhibits an ultra-wide effect absorption bandwidth (EAB) of 9GHz and a minimum Reflect Loss (RL) of -52.33dB. Furthermore, the layer structure of the foam enables the sample to rebound quickly when subjected to stress. The porous architecture effectively blocks heat conduction and radiation, resulting in an ultra-low thermal conductivity (0.036W/(m·K)), which enables the material to realize dual microwave-infrared stealth at the same time. This work provides new ideas and broaden the applications for multifunctional microwave absorbing materials.

UV-curable organic silicone grafting modified waterborne polyurethane acrylate: Preparation and properties

The organosilicon grafting copolymerization waterborne polyurethane acrylate composite coating (WPUA@KH570) with high surface properties was prepared by the UV curing method from mixing silicone monomer surface-modified ZnO (Si@ZnO) as photoinitiator to waterborne polyurethane acrylate (WPUA) emulsion. The effects of the polyurethane isocyanate index (R), the addition amount of hydrophilic chain elongator DMBA (wDMBA), the ratio of PU/PA on the stability of the synthesized WPUA emulsion were explored. The properties of the WPUA@KH570 composite coatings with different contents of organosilicon surface-modified ZnO were characterized by the particle size distribution meter, FTIR, XRD, SEM, UV–Vis–NIR spectrophotometer, contact angle (CA) and water absorption rate (WAR). The results showed that when R = 1.4, wDMBA = 0.04 and PU/PA = 0.6, the WPUA emulsion had an excellent stability. When the content of organosilicon modified ZnO reached 1.5 wt%, the CA increased to 90.6°, the WAR decreased to 15.4 %, and the absorbance reached 0.5. The WPUA@KH570 composite coating could be changed from hydrophilic to hydrophobic, which can step further promoted the surface properties, water resistance and UV absorption.

Solid polymer nanocomposite electrolytes based on poly(ε‐caprolactone)‐based waterborne polyurethane–polyethylene oxide and fluorine‐doped carbon quantum dot‐MXene

AbstractThe need for higher energy storage capability has encouraged researchers to move toward lithium‐metal batteries (LMBs). Due to the safety issue associated with liquid electrolytes, solid polymer electrolytes (SPEs) the main focus on polyethylene oxide (PEO) were at the center of the research. However, high crystallization, fast decomposition, and low thermomechanical stability has limited its application. Low lithium‐ion transference number () is another issue leading to polarization of the SPEs and consequently, triggering dendrite nucleation and growth. Here, we developed a series of SPEs based on PEO‐waterborne polyurethane (WPU) and nanoparticles of fluorine‐doped carbon quantum dot (fCQD) and MXene. The host polymer matrix was a blend of poly(ε‐caprolactone) (PCL)‐based WPU and PEO. The use of WPU and the nanoparticles increased the thermomechanical stability and suppressed PEO crystallinity through disrupting the spherulites growth and reducing the thermal stability of the crystallites. Using the WPU led to significant increase in () compared with previous reports. The prepared SPEs showed high‐electrochemical stability and ionic conductivity at and based on the results of cycling performance, a discharge capacity of 120.58 mAh/g and coulombic efficiency of 99.1% was achieved after 200 cycles.

Preparation and corrosion resistance of polyaniline and waterborne polyurethane composite coating film

AbstractPolyaniline (PANI) particles were synthesized using aniline (AN), dodecyl benzene sulfonic acid (DBSA), and ammonium persulfate (APS). The particles were analyzed using scanning electron microscope (SEM), X‐ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). A PANI/waterborne polyurethane composite material (PANI‐WPU) was obtained by combining it with polyethylene glycol (PEG600), diphenylmethane diisocyanate (MDI), dimethylol propionic acid (DMPA), N‐methyl pyrrolidone (NMP), and dibutyltin lauric acid (DBTDL). The structure was characterized by the FTIR spectrum. The mechanical characteristics of the coating film were evaluated with respect to the PANI content, as well as its water absorption, glossiness, electrochemical corrosion resistance, and acid and alkali resistance. The PANI/waterborne polyurethane film has a maximum tensile strength of 23 MPa, an elongation of 1012%, a pencil hardness of 5H, a flexibility of 2 mm, an impact resistance of 50 cm, the water absorption of 14.66%, and the glossiness of 99.9 at 60°. When the PANI content is 0.7%, the mechanical characteristics, glossiness, and anti‐corrosion performance of the composite film improve. The corrosion inhibition efficiency of the aqueous polyurethane coating film with PANI can reach 99.74%, as shown by the examination of electrochemical polarization curves and impedance spectra. The tinplate is coated with a 0.7% PANI‐WPU composite material and edge sealing. This coating provides excellent protection against acid and alkali resistance, as demonstrated by its ability to withstand immersion in 10% H2SO4 and 10% NaOH solution for 90 days without any paint peeling off.

Preparation and characterization of a novel high barrier mulching film with tunicate cellulose nanocrystals/sodium alginate/alkali lignin

In this study, the base film (CSL) was prepared by blending tunicate cellulose nanocrystals (TCNCs) extracted from tunicate shells, with sodium alginate (SA) and alkali lignin (AL). Then, the mulching film (CSL-WK) was prepared using water-borne polyurethane (WPU) as binder to install low-energy Kaolin on the surface of CSL film. The influences of composition with different concentrations on mechanical properties were studied. The tensile strength and elongation at break of CSL-WK film could reach 86.58 MPa and 50.49 %, respectively. The mulching films were characterized by degradability test, SEM, FTIR, and TGA. TCNCs had good compatibility with SA and AL, and a rough structure was formed on the surface of the film to improve the hydrophobicity. The barrier properties, including ultraviolet resistance, water contact angle, water vapor permeability, water retention, and flame retardancy, were tested. The results showed that CSL-WK films could block 97 % of ultraviolet light, reduce about 25 % of soil water loss, and self-extinguish within 7 s of open flame ignition. Note that the secondary spraying method significantly improved the barrier property of films. This study lays a foundation for the preparation of ecologically friendly, biodegradable, and high barrier mulching film, and expands the application of marine resources.

Bio-based adsorption foam composed of MOF and polyethyleneimine-modified cellulose for selective anionic dye removal

With the increase of sustainable development goal, the bio-based adsorption materials with high and selective dye removal are important for water treatment in the dyeing industry. In this paper, a bio-based adsorption foam composed of metal-organic frameworks (MOF) and polyethyleneimine (PEI)-modified cellulose was prepared by a three-step process, i.e., PEI modification of cellulose fibers (PC), MOF decoration of PEI-modified cellulose (MIL-53@PC), and in-situ foaming with polyurethane. PEI modification provides cellulose fiber with more active sites for both dye adsorption and MOF bonding. We found that MIL-53 crystals were tightly bonded on the surface of PC through hydrogen bonding. Because of the abundant adsorption sites (e.g., amines, iron oxide group), the MIL-53@PC demonstrated high adsorption capacity and selectivity for anionic dye (e.g., 936.5 mg/g for methyl orange) through electrostatic interaction and hydrogen bonding. Finally, MIL-53@PC particles were blended with a waterborne polyurethane prepolymer to prepare a three-dimensional hydrophilic foam (MIL-53@PC/PUF), which not only maintained high adsorption capacity and selectivity of MIL-53@PC and also improved its recyclability and reusability. The MIL-53@PC/PUF offers a promising solution for dye wastewater treatment.

Preparation of Ceramic Fiber Threads with Enhanced Abrasion Resistance Performance.

Ceramic fiber thread is one of the key components in flexible external thermal insulation blankets, and it has been applied in various fields as a flexible ceramic fibrous material with excellent deformability and high-temperature resistance. However, ceramic fiber threads are often subjected to reciprocating friction motion at specific bending angles, making them highly susceptible to abrade and fracture. Enhancing the abrasion resistance performance of ceramic fiber threads under bending conditions is the future trend and remains a significant challenge. Hence, we design and construct a novel polyurethane-modified coating on the ceramic fiber threads to improve their abrasion resistance performance. The effects of the types and concentrations of modifiers on the microstructure, abrasion resistance property, and tensile property of ceramic fiber threads are systematically investigated. The ceramic fiber threads, after modification with hexamethylene diisocyanate waterborne polyurethane (HDI-WPU) with a concentration of 3%, exhibit excellent abrasion resistance properties. The number of friction cycles at fracture of the modified ceramic fiber thread is more than three times, and the tensile strength is more than one and a half times, that of the original ceramic fiber thread, demonstrating the great potential of the HDI-WPU modifier for enhancing the abrasion resistance performance of ceramic fiber threads.

Particle elastic modulus analysis of waterborne polyurethane nanoparticles by ultrasound scattering method

Abstract When water is dropped gradually to an acetone solution of concentrated polyurethane containing ionic functional groups, a phase inversion occurs and nanoparticles of waterborne polyurethane (WPU) are formed. Evaporation of water from such aqueous particle suspensions yields polyurethane sheets, but the properties of these sheets are different from those obtained by evaporation of solvent from WPU acetone solutions. In this study, ultrasonic spectroscopy analysis combined with an ultrasonic scattering theory was performed on the microparticle suspensions to evaluate the elastic modulus of the individual particles. The nanoparticles obtained by phase inversion are stabilized by ionic substituents, and the bulk modulus of the particles at 30 wt% was shown to be different from that of bulk sample obtained by drying acetone, in spite of the fact that they are the same polymer material. Even after 95% concentration beyond the maximum packing concentration, the film properties were observed to be particle size dependent, suggesting that the nanostructure plays an important role in film properties.

Double crosslinked networks waterborne polyurethane with self-healing, recyclable and antibacterial functions based on dynamic bonds and used for temperature/light sensor

Waterborne polyurethanes with excellent mechanical properties, self-healing under mild controlled conditions and multiple functions are a potential alternative for preparing sensor materials with a wide application prospect. Herein, we introduced dynamic ditelluride bonds and trimethylolpropane into waterborne polyurethane main chains to achieve dynamic polymer chains while maintaining the stability of crosslink networks; subsequently, zinc ions were added to form ionic bonds with carboxyl groups between molecular chains to prepare self-healing waterborne polyurethanes (DTe-WPU-Zn-x) with double crosslinked networks containing double dynamic bonds. The prepared waterborne polyurethane film exhibited excellent mechanical properties (36.08 MPa), satisfactory elongation (665.83 %), and rapid self-healing efficiency (self-healing efficiency with 84.42 % after 90 min of visible-light irradiation). Benefiting from the excellent self-healing efficiency of DTe-WPU-Zn-3, the film fragments can be recycled under ethanol and pressure with lighting for 2 h, and its tensile stress can recover more than 80 % of its original properties after three recycling processes, which is rarely reported for double crosslinked polymers. Furthermore, owing to the combination of telluric radicals and metal ions, the film also has excellent antibacterial properties, with 99.6 % and 96.2 % against E. coli and S. aureus, respectively. Importantly, depending on the stable double crosslinked networks, the prepared sensor has long-term stability and can sensitively monitor changes in human body temperature, and the sensor also has a sensitive light response due to the photodynamic response of ditelluride bonds on polymer chains. In addition, the sensor still has better strain, temperature, and light response after recycling treatment. This research provides a facile method to fabricate environmentally friendly water-dispersible polymers with excellent properties and multiple functions, which have potential applications in the field of smart devices and human–computer interaction.

Stratification of polyisocyanate in two-component waterborne polyurethane films

The coatings industry continually seeks advancements in waterborne two-component polyurethane (2 K WBPU) systems, given their potential for environmentally friendly applications and superior film properties. This study explores the mechanistic aspects of film formation in 2 K WBPU coatings formulated with an acrylic polyol and a polyisocyanate (PIC) derived from a trimer of hexamethylene diisocyanate (HDI-trimer). To enhance water dispersibility—a key parameter in industrial applications—the HDI-trimer is modified with a short polyethylene glycol, producing a hydrophilically modified PIC (hmPIC). While prior studies identified hmPIC as an effective reactive plasticizer for the polyol, the common practice of adding unmodified HDI-trimer (uPIC) to hmPIC for moisture sensitivity reduction necessitates a deeper understanding of film properties. Using fluorescence resonance energy transfer (FRET) and confocal fluorescence microscopy, we investigated the effects of blending uPIC with hmPIC on coalescence, phase separation, and film stratification in 2 K WBPU systems. Notably, environmental factors like relative humidity were found to influence film stratification significantly. This finding has critical implications for coating performance, such as durability and water resistance. A novel method was also introduced to monitor water permeation within stratified films, offering a valuable tool for optimizing film properties in real-world applications. This study underscores the importance of strategic component interactions in polymer coatings, suggesting that controlled film stratification can significantly enhance film performance in industrial settings.

Synergistic of UV resistant water-borne polyurethane sizing with metal chelation to enhance the interfacial properties of CF/PA6 composites

Currently, the challenge of achieving robust adhesion between carbon fibers and resins remains a focal point for exploring composites. This study introduces a waterborne polyurethane sizing agent employing natural biomass derived sodium alginate as the foundational material. The infusion of 4,4-dihydroxybenzophenone as a chain ext ender imparts the sizing agent with ultraviolet (UV) absorption capabilities. Additionally, chelation between Ca2+ and sodium alginate was harnessed to amplify the interfacial adhesion between the fibers and sizing agent, thereby fostering a more tenacious connection for the two entities and fortifying the fiber-resin interface. The ramifications of varying sizing agent concentrations on composite materials were methodically explored. Comparative analysis conducted against untreated CF composites discloses noteworthy enhancements in the interlaminar shear strength (ILSS) by 46 %, bending strength by 67 %, and interface shear strength (IFSS) by 57 % for CF-1.5 wt%/PA6 composites. Notably, even after enduring a week of xenon lamp aging, the mechanical integrity preserved at approximately 98 %. This inventive methodology presents a fresh avenue for bolstering the characteristics of CF composites.

UV-curable acrylic end-capped amphoteric waterborne polyurethane coatings

Waterborne polyurethane dispersions (WPUs) are environmentally friendly coatings since they present low amount of volatile organic compound amounts (VOCs). In the majority of the WPUs the dispersions are balanced with anionic groups and accordingly their stability at low pH is limited. In order to this drawback to be solved, in this work a tertiary amine containing chain extender (triethanolamine, TEOA) was introduced together with a conventional internal emulsifier (carboxylic acid) in acrylic end-capped polyurethane dispersions giving rise to amphoteric UV curable WPUs. After adding a radical photo-initiator and film formation, the coatings were cured under UV irradiation. The properties of amphoteric and anionic dispersions were compared. The best properties were obtained for the samples containing a 1/1 amine/acid molar ratio. Thus, while the anionic dispersions coagulated at low pH values, the 1/1 amphoteric dispersion showed high stability to pH changes. After curing this sample with UV irradiation, the gel content of the film was higher and the water vapour transmission rate was lower than that of the anionic polyurethane because of the strong acid/base interaction. The results showed that the amphoteric WPUs are promising for various applications, offering stability over a wider pH range than traditional formulations.

Transparent biodegradable composite plastic packaging film from TEMPO-oxidized cellulose nanofibers

In this research, we develop a method to create biodegradable food packaging films. Initially, TEMPO-oxidized cellulose nanofiber (TOCNF) undergoes sonication to produce well-dispersed single-strain nanofibers. These nanofibers are then blended with waterborne polyurethane (WPU) to enhance their extensibility. To further enhance compatibility between these two components, a non-ionic surfactant, Tween 80, is introduced into the TOCNF/WPU mixture to improve the dispersion of the WPU within the blend. The addition of Tween 80 significantly increases the transparency of the resulting film (Transmittance: 89.4 %, Haze: 2.2 %). Furthermore, the incorporation of the surfactant effectively reduces the formation of wrinkles and cracks during the film drying process, preventing adverse impacts on the film's barrier properties. The thin film further undergoes esterification crosslinking with citric acid to remove its hydrophilic groups for better water vapor barrier properties. The resulting bio-based packaging film exhibits remarkable transparency, strong biodegradability, and superior gas-barrier properties (water vapor and oxygen) compared to commonly used food packaging.

Pickering emulsion approach: A novel strategy to fabricate waterborne polyurethane with enhanced abradability and water-resistance comparable to that of solvent-based coating

The urgent requirement of replacement for solvent polyurethane (PU) makes waterborne polyurethane (WPU) coating more attractive and popular in many industrial areas. However, the simultaneous realization of good dispersion stability and high performance of the cured films especially water resistance remains challenging. Herein, we propose a novel and facile Pickering emulsion approach to fabricate WPU with enhanced abradability and water-resistance comparable to that of solvent-based PU coating. In this approach, the hydrophobic polyurethane synthesized by poly-addition reaction in ethyl acetate is directly dispersed into water with SiO2 nanoparticles as Pickering stabilizer followed by subsequent evaporation of the remaining solvent to obtain Pickering waterborne polyurethane dispersion (PWPU dispersion). The ability of SiO2 to stabilize emulsion can be modulated by hydrophobic modification with propyltriethoxysilane (PTS). SiO2 nanoparticles with an optimal PTS-grafting rate of 2.8 wt% enables the PWPU dispersion with excellent long-term, chemical, thermal, and freeze-thaw stability. The highly-transparent composite films with honeycomb structures are readily formed by casting PWPU dispersion at room temperature. The thermal and mechanical properties of PWPU films are comparable to or superior to solvent-borne polyurethane (SPU) and self-emulsifying waterborne polyurethane (SWPU) films. Moreover, the water absorption of the PWPU-5 film is approximately 20 times lower than that of SWPU, demonstrating the excellent water-resistance. We further validated the coating performance of PWPU for leather finishing. The hydrophobicity, abrasion resistance and water vapor permeability of PWPU-coated leather are superior to those of SPU and SWPU-coated leather.

Mechanical properties and microstructure of waterborne polyurethane-modified cement composites as concrete repair mortar

With the increase in service life, the durability of a large number of concrete structures deteriorates year by year under the influence of the external environment, requiring urgent repair and reinforcement. Ordinary cement concrete materials have disadvantages such as high brittleness, low tensile strength, poor bonding ability, and insufficient durability, making it difficult to meet the repair needs of high-quality building structures. Therefore, self-synthesized anion WPU was used to study its effect on the mechanical properties of cement-based repair mortar. The research found that waterborne polyurethane (WPU)-modified cementitious composite repair materials exhibit better bonding strength with old concrete substrates compared to traditional cement-based materials. Additionally, the incorporation of WPU significantly reduces the brittleness of the repair material, ensuring enhanced efficiency in the repair process. However, according to the hydration heat test results, the addition of WPU delays the hydration process of the composite repair materials. In addition, the addition of WPU enhances the flexibility and bonding ability of the materials, with flexural strength and tensile strength at the age of 28 days reaching 13 MPa and 6 MPa, respectively. Through stress‒strain curve analysis, it was found that the maximum strain amplification of WPU cement mortar can reach 134 %. Combined with SEM testing, it was observed that cured WPU films were present in specimens aged 28 days with P/C ratios of 10 % and 15 %. WPU and cement hydration products permeate each other, forming a three-dimensional polymer network structure, improving the pore structure, and fully exerting the flexibility of WPU. This also validates the experimental results of increased ultimate tensile strain. WPU cement-based composite repair materials have higher bonding strength at a high P/C ratio (15 %), and WPU alone, used as an interface agent for pretreating the interface of old concrete, can improve the interface bonding strength, up to twice that of the group without the surface agent.