Polyurethane Emulsion Research Articles

Facile Fabrication of Eco-Friendly Waterproof Breathable Nanofibrous Membranes with Asymmetric Wettability via Electrospray of Waterborne Polyurethane Emulsion

Facile Fabrication of Eco-Friendly Waterproof Breathable Nanofibrous Membranes with Asymmetric Wettability via Electrospray of Waterborne Polyurethane Emulsion

Synthesis and characterization of waterborne polyurethane‐based marine antifouling coating modified via glycerol laurate

AbstractMarine biofouling is a major international challenge since it is responsible for several environmental problems and economic losses. Developing a novel antifouling coating with good water resistance, adhesion, and controlled degradation performance is crucial to solving the problem. Herein, a series of waterborne polyurethane emulsions were synthesized using the prepolymerization chain expansion and self‐emulsification method, with varying contents of glycerol laurate (GL) as the post‐chain extender. The findings demonstrated a notable enhancement in the controllable degradation performance, adhesion, marine antifouling properties, and water resistance with an increase in the concentration of GL. In particular, the film exhibited the most optimal overall properties when the introduction amount of GL was 2 wt%. The absorption rate of the artificial seawater (ASW) reached a state of equilibrium when GWPU2 was immersed in ASW for 60 days, with a final value of approximately 18.5%. The release rates of the GWPU2 antifouling coatings were observed to be the lowest at approximately 120 days, with a rate of approximately 37.59 μg/cm2/day. The long‐term antifouling capability of the GWPU resins was demonstrated in marine field tests, wherein they exhibited sustained antifouling activity for a period exceeding 9 months. In particular, GWPU2 exhibited noteworthy antifouling performance.

Preparation and Characterization of Fluorinated Acrylate and Epoxy Co-Modified Waterborne Polyurethane.

Conventional waterborne polyurethane (WPU) has poor water resistance and poor overall performance, which limits its application in outdoor coatings. A solution to this problem is urgently needed. The introduction of fluorine-containing groups can effectively improve the water resistance of WPU. In this study, a new fluorinated chain extender (HFBMA-HPA) synthesized by free radical copolymerization and epoxy resin (E-44) were used to co-modify WPU, and five waterborne fluorinated polyurethane (WFPU) emulsions with different fluorine contents were prepared by the self-emulsification method. The effects of HFBMA-HPA content on the emulsion particle properties, coating surface properties, mechanical properties, water resistance, thermal stability, and corrosion resistance were investigated. The results showed that the WFPU coating had excellent thermal stability, corrosion resistance, and mechanical properties. As the content of HFBMA-HPA increased from 0 wt% to 14 wt%, the water resistance of the WFPU coating gradually increased, the water contact angle (WCA) increased from 73° to 98°, the water absorption decreased from 7.847% to 3.062%, and the surface energy decreased from 32.8 mN/m to 22.6 mN/m. The coatings also showed impressive performances in the adhesion and flexibility tests in extreme conditions. This study provides a waterborne fluorinated polyurethane material with excellent comprehensive performance that has potential application value in the field of outdoor waterproof and anticorrosion coatings.

Study on the effect of film-forming agent composition on moisture and heat resistance of basalt fiber composites

Abstract Resistance to hygrothermal aging is the key to the popularization and application of basalt fiber composites in the field of electrical equipment, so it is crucial to develop fiber surface-modified coatings suitable for basalt fibers with excellent hygrothermal resistance. In this study, the performance changes of basalt fiber composite samples treated with four types of surface coatings under artificially accelerated hygrothermal aging test were comparatively analyzed, and the mechanism of different components in the surface coatings was further analyzed. The results showed that the use of epoxy resin emulsion co-mingled with acrylic emulsion as the film-forming agent could significantly improve the mechanical properties of the samples. The use of epoxy resin emulsion co-blended with polyurethane emulsion as the film-forming agent improved the insulating properties and moisture and heat resistance of the samples. Further, the use of 5:1:1 epoxy emulsion, acrylic emulsion, and polyurethane emulsion co-blended as the film-forming agent component can ensure the insulation and hygrothermal resistance of the samples while taking into account the mechanical properties. After 120 hours of wet-heat aging, the breakdown field strength was increased by 22%, leakage current and dielectric loss angle was increased by 10%, and the mechanical properties were also significantly improved compared with the sample with epoxy emulsion as the main film-forming agent. In summary, through the compounding of the film-forming agent emulsion components, the optimization of the moisture and heat resistance of basalt fiber composites can be achieved, and the use of the mass percentage of 5:1:1 for the three types of emulsions blended to prepare the fiber surface coatings is more suitable for the treatment of basalt fibers to prepare the electrician’s equipment.

Durability enhancement of cement-based repair mortars through waterborne polyurethane modification: Experimental characterization and molecular dynamics simulations

With the rapid development of society and economy, more and more concrete structures are facing severe damage and deterioration, requiring repair. However, traditional cement repair materials generally suffer from brittleness, poor durability, and other deficiencies, failing to meet the demands for durable repair materials. In this study, we designed and synthesized an anionic waterborne polyurethane (WPU) emulsion for cement-based materials, characterized its performance, and applied it to modify cement mortars, evaluating the durability of the WPU-modified cement composite repair materials. The experimental results showed that the cured WPU exhibited good radiation resistance, tensile properties, and alkali resistance, and the WPU emulsion demonstrated good compatibility with cement mortars. The WPU-modified cement mortars exhibited improved resistance to drying shrinkage, thermal expansion, freeze-thaw cycles, and water penetration, with increasing WPU content further enhancing the durability of mortar. Simultaneously, the organic-inorganic phase distribution and microstructure of the WPU-modified cement-based composites were investigated. WPU can interact with the cement paste, forming an interpenetrating network structure and increasing the material's density. Finally, molecular dynamics simulations were employed to study the adsorption behavior of WPU on calcium silicate hydrate (CSH) and the transport of water molecules in WPU-modified CSH nanopores. The study found that WPU spontaneously adsorbed onto the CSH surface through hydrogen bonding and weakened the transport efficiency of water molecules in CSH nanopores. Overall, the WPU modification enhanced the density and durability of the cement repair mortars, and the MD method provided molecular-scale insights into the improved water penetration resistance. This study hopes to aid in the design and practical application of polymer-modified cement-based repair materials.

Synthesis and properties of waterborne polyurethane acrylate emulsions with high bio‐based content

AbstractThe bio‐based hydrophilic monoglycerol succinate was synthesized and reacted with bio‐based raw materials including polyols, pentamethylene diisocyanate, 1,4‐butanediol, to prepare the waterborne polyurethane acrylate (Bio‐WPUA) emulsions with high bio‐based content. The effect of bio‐based polyol categories including poly(trimethylene ether glycol), poly(tetrahydrofuran), and castor oil on the properties of Bio‐WPUA and its films were studied. The structure, thermal stability, crystallinity, contact angle, and mechanical properties of Bio‐WPUA film were characterized with fourier infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X‐ray diffraction, contact angle analyzer, and mechanical tensile testing. It was found that Bio‐WPUA film containing poly(trimethylene ether glycol) as the soft‐segmented display good tensile stress, thermal stability, and water resistance with 1.38% of the water absorption rate, while Bio‐WPUA containing castor oil polyol as the soft‐segmented had good tensile strain and low‐temperature film‐forming properties with excellent film properties. The bio‐carbon content of Bio‐WPUA was high up to 40% according to ASTM D6866‐22, and possesses good physical mechanical and chemical resistance performance. The results provide theoretical guidance for the synthesis of polyurethane emulsions with bio‐based materials instead of petroleum‐based materials.

Waterborne polyurethane containing fluorosilicone coating: to endow leather with enduring hydrophobicity and mechanical properties

Natural leather-based materials possess a combination of air permeability, wear resistance, and plasticity. However, conventional leather products have inherent limitations that make them unsuitable for unconventional applications. Therefore, it is necessary to develop new capabilities in order to overcome these limitations. In this study, we explored the conversion of regular leather into a high-strength product with hydrophobic properties through surface engineering. To achieve this, we synthesized polysiloxane-modified fluorinated waterborne polyurethane emulsions as functional coatings using emulsion polymerization. The structure and properties of the treated leathers were characterized using techniques such as Fourier transform infrared, thermogravimetry, X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The results demonstrated that the synthesized polysiloxane-modified fluorinated waterborne polyurethane successfully penetrated and combined with the fibers of the leather, resulting in excellent hydrophobicity. The water contact angle increased to 124.3°. Furthermore, the tensile strength and tear strength of unfinished leather are 875 N and 114 N, respectively. The application of waterborne polyurethane-derived functional additives as coatings resulted in a significant increase in tensile and tear strength of the leather by 60 N and 16 N, respectively. In addition, the softness of the leather increased from 7.6 mm to 10.09 mm. Overall, the use of this functional waterborne polyurethane coating will contribute to the diversification of leather applications.

Synthesis and characterization of non-ionic flame-retardant waterborne polyurethane.

Waterborne polyurethane (WPU) offers many advantages and is widely used in coatings, leathers, adhesives, biomaterials, and other consumer products. However, WPU is highly flammable. Many reactive flame retardants have been developed, but their char formation efficiency is still unsatisfactory, and the melt dripping during combustion has not been effectively suppressed. In this paper, a novel phosphorus-containing flame retardant with dihydroxy groups, (6-((4-hydroxyphenyl)((4-hydroxyphenyl)amino)methyl) dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (PHAD), was successfully synthesized and incorporated into WPU molecular chain as a chain extender, thereby synthesizing a series of non-ionic flame-retardant waterborne polyurethane (NFRWPU) emulsions. The chemical structure of NFRWPU was successfully characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance. With the help of a thermogravimetric analyzer, scanning electron microscope and other instruments, some key performance parameters of NFRWPU in applications were investigated, including: physical, mechanical, and thermal stability and flammability. Some important experimental results include: both the particle size and viscosity of the emulsion increase gradually with increasing PHAD content, and when the PHAD content reaches 12%, the average particle size of emulsion increases to 106.6 nm with a viscosity of 89 mPa s; with the addition of PHAD, the tensile strength of NFRWPU initially increased and then decreased, while the elongation at break showed a continuous downward trend. The maximum tensile strength reached 22.63 MPa, and the minimum elongation at break dropped to 1060%; the addition of PHAD improved the thermal stability and flame retardancy of the film, with the highest limiting oxygen index value reaching 25.6% and the maximum carbon residue increasing to 6.5%. All these results indicate that NFRWPU is a promising flame retardant WPU considering the comprehensive performance.

Self-adhesive, stretchable waterborne polyurethane-based flexible film as wearable conformal strain sensor for motion and health monitoring

Wearable tensile strain sensors are of great importance in both motion monitoring and next-generation, personalized health diagnostics. The accuracy, reliability and stability of the signals obtained from these sensors are significantly dependent on the conformal contact between the flexible sensor and the skin surface. In this study, we have developed a flexible double-layer film as a wearable tensile strain sensor by a simple solution-blending method and a layer-by-layer spraying method. D-sorbitol was incorporated into a waterborne polyurethane (WPU) emulsion to enhance film adhesion, achieving a strength of 7.91 N/m, and to disrupt hydrogen bonds between the WPU chains. This disruption facilitates more straightforward conformational changes of the chains under stress, thereby substantially enhancing the mechanical flexibility of the film. The sensing layer was subsequently constructed by spraying silver microparticles, exhibiting extremely high sensitivity (gauge factor = 103.01) over a 19.3% strain range. This sensor can effectively monitor joint motions and subtle muscle movements as tensile strain sensors.

Synthesis of a Reactive Cationic/Nonionic Waterborne Polyurethane Dye Fixative and Its Application Performance on Viscose Fiber Fabrics.

A series of cationic waterborne polyurethane (CWPU) emulsions was synthesized with isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) as hard segments; polyol (N210) and polyethylene glycol (PEG-2000) as soft segments; N-methyldiethanolamine (MDEA) as a hydrophilic chain extender; and trimethylolpropane (TMP) as a crosslinker. Then, the effects of the R-value, MDEA content, and TMP content on the properties of the CWPU emulsion, film, and fabric treatment were investigated. The results indicated that when the R-value was 3.0, the MEDA content accounted for 4.0% of the solid and the TMP content accounted for 1.0% of the solid. CWPU has excellent storage stability. Applying it to the fixing treatment of the viscose fiber fabrics can effectively improve the color fastness to rubbing, elasticity, surface smoothness, and anti-static properties.

Waterborne polyurethane sizing agent with excellent water resistance and thermal stability for improving the interfacial performance of carbon fibers/epoxy resin composites

In order to improve the water-resistance and thermal stability of waterborne polyurethane (WPU), a series of silane and maleimide co-modified waterborne polyurethane emulsions (WPU-M-S) were prepared. Because of the high bond energy of the Si-O bond in silane and the rigid ring in 4-HPM, the WPU-M-S sizing agent achieved better thermal stability. Meanwhile, the excellent hydrophobicity of silane enhances its water resistance. Then, the electrochemical anodic oxidation (EAO) treatment was used to activate the surface of the carbon fibers to introduce carboxyl and hydroxyl groups. Next, WPU-M-S was attached to the carbon fiber by the sizing process. For compound modified carbon fibers, the water contact angle increased, and the single filament tensile strength was also improved. The WPU-M-S sizing agent can react with both the active groups on the fiber surface and the amino groups in the epoxy resin system, thereby achieving a significant improvement in the composite interfacial bonding performance. The interlaminar shear strength (ILSS) of the sizing carbon fibers reinforced epoxy resin composite was promoted to 59.80 MPa, with an increase of 41.61% compared with unsized carbon fiber.

Synthesis and characterization of waterborne polyurethane-based ink binder modified via a silane coupling agent

The development of high-performance waterborne polyurethane ink binder presents challenges due to the lack of outstanding water resistance, adhesion, and heat resistance in traditional waterborne polyurethane. Herein, series of waterborne polyurethane emulsions were synthesized using the pre-polymerization chain expansion and self-emulsification method, with varying contents of 3-aminopropyl triethoxysilane as the modified post-chain extender. The effect of varying the concentration of 3-aminopropyl triethoxysilane on the characteristics of waterborne polyurethane dispersions and films was investigated. The results indicated that there was a significant improvement in adhesion, thermal stability, and water resistance with an increase in the concentration of 3-aminopropyl triethoxysilane. Specifically, When the introduction amount was 3 wt%, the resulting film exhibited the best overall properties, including a tensile strength of 48.4 MPa, water absorption of 4.3 wt%, shear strength and adhesion of 3.9 MPa and 3.86 MPa respectively, as well as a T-peel strength of 14.9 N/mm. This work provided meaningful guidance for developing a novel waterborne polyurethane-based ink binder with strong adhesion, high mechanical properties, and excellent water resistance.

Aqueous Cationic Fluorinated Polyurethane for Application in Novel UV-Curable Cathodic Electrodeposition Coatings.

Aqueous polyurethane is an environmentally friendly, low-cost, high-performance resin with good abrasion resistance and strong adhesion. Cationic aqueous polyurethane is limited in cathodic electrophoretic coatings due to its complicated preparation process and its poor stability and single performance after emulsification and dispersion. The introduction of perfluoropolyether alcohol (PFPE-OH) and light curing technology can effectively improve the stability of aqueous polyurethane emulsions, and thus enhance the functionality of coating films. In this paper, a new UV-curable fluorinated polyurethane-based cathodic electrophoretic coating was prepared using cationic polyurethane as a precursor, introducing PFPE-OH capping, and grafting hydroxyethyl methacrylate (HEMA). The results showed that the presence of perfluoropolyether alcohol in the structure affected the variation of the moisture content of the paint film after flash evaporation. Based on the emulsion particle size and morphology tests, it can be assumed that the fluorinated cationic polyurethane emulsion is a core-shell structure with hydrophobic ends encapsulated in the polymer and hydrophilic ends on the outer surface. After abrasion testing and baking, the fluorine atoms of the coating were found to increase from 8.89% to 27.34%. The static contact angle of the coating to water was 104.6 ± 3°, and the water droplets rolled off without traces, indicating that the coating is hydrophobic. The coating has excellent thermal stability and tensile properties. The coating also passed the tests of impact resistance, flexibility, adhesion, and resistance to chemical corrosion in extreme environments. This study provides a new idea for the construction of a new and efficient cathodic electrophoretic coating system, and also provides more areas for the promotion of cationic polyurethane to practical applications.

Facile and scalable fabrication process of electroluminescent filament with high luminescent efficiency

Electroluminescent (EL) filament has received much more attention on the application of smart and displayable textiles. In this work, the co-axial wet-spinning method was utilized to prepare a core/sheath filament with a copper wire as core electrode and thermal polyurethane (TPU) contained EL material of ZnS:Cu as sheath. The outside was wire-winded helically and then was coated with silver coating via magnetron sputtering, which was used as the other electrode. About 10 nm thickness silver coating was afforded after 90 s sputtering, which ensured Ag coating continuity. Finally, the filament was immersed into a waterborne polyurethane (WPU) emulsion to endow a transparent protective layer. When the ratio of Zn:S/TPU was 1:1, the as-obtained EL filament exhibited the highest luminescent efficiency. This strategy made almost all EL materials excited, which provided a promising and facilely scalable method to fabricate EL filament with high utilization rate of EL materials and luminescent efficiency.

Synthesis and Characterization of Self-matting Waterborne Polyurethane Emulsion Modified by Silane Coupling Agent

Silane coupling agent has low surface energy, and its side chain contains organic groups that are easy to participate in the reaction. In the process of film formation, Si is easy to aggregate to the surface, which has the advantages of water and oil resistance, good permeability, low glass transition temperature and good thermal stability. Therefore, in this paper, four silane coupling agents such as KH540, KH550, KH560 and AEAPTMS were used to hydrophobically modify waterborne polyurethane (WPU). A series of self-matting waterborne polyurethane solutions were prepared with HTPB and PTMG as soft segments and IPDI as hard segment. The siloxane introduced in the WPU structure was hydrolyzed to form a Si-O-Si hydrophobic structure, which increased the crosslinking degree of the system and improved the water resistance of the system. It was also beneficial to increase the particle size and improved the extinction performance of WPU. Through comprehensive analysis, we found that the most suitable silane coupling agent for modifing self-matting WPU was AEAPTMS. After modification, the gloss of WPU leather coating can be reduced to 0.4 GU, and the surface energy can be reduced to 19.72 mJ/m2. It greatly improved the extinction performance and water and solvent resistance of WPU, and has a wide application prospect in the field of WPU leather finishing agent.

Two-step method to realize continuous multi-wall carbon nanotube grafted on the fibers to improve the interface of carbon fibers/epoxy resin composites based on the Diels-Alder reaction

A new simple and continuous method was developed for chemically grafting multi-wall carbon nanotubes (MWCNTs) onto the surface of carbon fibers (CF) to improve the interlaminar properties of composites. In this method, maleimide-grafted waterborne polyurethane emulsion and furan functionalized MWCNTs were prepared. Then, based on the Diels-Alder reaction under mild reaction conditions (60 °C), CF/MWCNTs multi-scale reinforcements (MSCF) were successfully prepared through a two-step method of MWPU sizing and MWCNTs ultrasonic grafting, which overcame the complex process flow, greatly shortened the preparation time and avoided damage to fibers. The successful grafting of MWCNTs was proved by the results of SEM and HRTEM. After grafting MWCNTs, the interface between the matrix and fibers was enhanced. The interlaminar shear strength (ILSS) and flexural strength of MSCF/epoxy reinforced composites were promoted to 64.54 MPa and 981.95 MPa, which was prominently increased by 52.84% and 32.32%, respectively. In addition, this process could match the current production of carbon fibers for commercialization, but further research was expected to control the grafting amount of MWCNTs and their impact on performance.

Self-healing polyurethanes with ultra-high-strength via nano-scaled aqueous dispersion of lignosulfonates

How to overcome the dilemma between self-healing capacity and the mechanical strength for polyurethane materials is an intriguing but challenging topic. Taking advantage of the nano-scaled dispersion of the lignosulfonates in tailored waterborne polyurethane (WPU) emulsion, herein an aqueous dispersion strategy was proposed. Different from the previously reported methods, it is simple, efficient and environmentally friendly. The prepared self-healing polyurethane exhibited an ultra- high tensile strength of 51.4 MPa (higher than previously reported results) combined with a elongation at break of 670% when merely 6 wt% of lignosulfonate was introduced into the WPU system. Upon undergoing three cycles of thermal processing, a tensile strength higher than 30 MPa was still remained. Atomic Force Microscope (AFM) combined with Variable-Temperature Infrared Spectroscopy (V-FTIR) confirmed the existence of the nano-scaled lignosulfonate aggregates within the WPU matrix and the reinforcing mechanism was discussed from a viewpoint of the intermolecular interactions. V-FTIR further revealed the origin of the self-healing from the detected dissociation of the oxime-carbamate bonds with the increased temperature. This nano-scaled aqueous dispersion strategy demonstrates a high potential in designing polyurethane materials with balanced self-healing performance and mechanical properties.

Enhanced thermal insulation performance of polyethylene glycol-based polyurethane/W-doped VO2 composite phase change coating

Polyurethane (PU) is widely used in construction, fabric, leather and other fields due to its advantages of good heat resistance and high strength. However, there are few reports on the introduction of composite phase change materials into PU emulsion to synergistically improve its thermal insulation performance. In this paper, W-doped VO2 (W-VO2) particles were first prepared by hydrothermal method. Then, polyethylene glycol 1000 (PEG1000) was used as a soft segment to prepare polyethylene glycol-based polyurethane (PEG-PU) emulsion by prepolymerization dispersion method. Finally, W-VO2 was added to obtain PEG-PU/W-VO2 composite emulsion and film. Based on a series of results, the phase transition temperature of W-VO2 decreased from 67.7 °C to 52.2 °C. Furthermore, sunlight simulation experiments demonstrated that the thermal insulation performance of PEG-PU/W-VO2 composite film was significantly improved under the synergistic effect of PEG1000 and W-VO2. Specifically speaking, compared with PU film, the infrared isolation rate of PEG-PU/W-VO2 composite film increased by 59.3 %. Meanwhile, the infrared reflective and heat preservation performance increased by 20.5 °C and 15 °C, respectively. In conclusion, the development of this research is helpful for the development of thermal insulation coating, which is of great significance to meet the current needs of society.

Preparation of biodegradable recycled fiber composite film using lignin-based polyurethane emulsion as strength agent

Poor wet mechanical and barrier properties restrict cellulose-based materials from replacing petroleum-based plastics. Herein, an environmentally benign blocked lignin-based water-borne polyurethane emulsion which could be stored stably was prepared for the development of a hydrophobic, translucent, and biodegradable recycled fiber composite film through a blocked terminal isocyanate group. The tensile strength, Young's modulus, and toughness of the film were determined to be 48.15 MPa, 4.66 GPa, and 755.93 kJ m−3, respectively, which were 2.7, 3.9, and 4.3 times higher than of control. Besides, the composite film showed excellent water stability with improved water contact angle (114°) and wet strength (30.60 MPa) compared to the control. Furthermore, the composite film manifested excellent UV- blocking properties and it had good thermal stability. The developed functionally integrated composite film with exceptional physiochemical properties is expected to be applied as a green packaging and construction material.

Preparation and pH Detection Performance of Rosin-Based Fluorescent Polyurethane Microspheres.

Rosin-based fluorescent polyurethane emulsion (FPU) was prepared using isophorone diisocyanate, ester of acrylic rosin and glycidyl methacrylate, 1,5-dihydroxy naphthalene (1,5-DN), and 1,4-butanediol as the raw materials. Then, rosin-based fluorescent polyurethane microspheres (FPUMs) were successfully prepared by suspension polymerization method using FPU as the main material, azodiisobutyronitrile as the initiator, and gelatin as the dispersant. FPUMs were characterized by Fourier transform infrared spectra, thermogravimetric analysis, optical microscopy, scanning electron microscopy and fluorescence spectra, and the response performance of FPUMs to pH was studied. The results showed that FPUMs were successfully prepared. With the increase of the level of 1,5-DN, the particle size of FPUMs increased gradually, and the fluorescence intensity increased first and then decreased. When the level of 1,5-DN was 3 wt.%, the average particle size was 49.3μm, the particle distribution index (PDI) was 1.05, and the fluorescence intensity was the largest (3662 a.u.). The fluorescence intensity of FPUMs increased linearly with the decrease of pH, which can be used for pH detection in solution. Furthermore, the FPUMs exhibited good thermal stability, anti-interference and recoverability.