Castor Oil-based Waterborne Polyurethane Research Articles

Robust self-healing capacity and high mechanical properties of castor oil-based waterborne polyurethane based on “kill two birds with one stone” strategy

Achieving ideal combination of high self-healing efficiency and good mechanical properties is of significance for the breakthrough in the application of self-healing materials. Herein, the functionalized castor oil-based waterborne polyurethane (DA-CWPU) was constructed based on “killing two birds with one stone” molecular design strategy with the addition of self-healing monomer D-A adduct. Firstly, D-A adduct containing flexible D-A bonds and rigid ring structure was prepared by D-A reaction with furfuryl alcohol (FA) and bismaleimide (BMI) as raw materials, which could not only effectively enhanced the self-healing ability of the material, but also ensured the strong mechanical properties. Then, DA-CWPU emulsion with favourable self-healing and mechanical properties was synthesized by the polymerization of castor oil (CO), isophorone diisocyanate (IPDI) and D-A adduct. The DA-CWPU film has preferable self-healing efficiency (93 % at 100 °C for 50 min), unique shape memory effect (rehabilitate after heating at 100 °C for 45 s), good toughness (485 MJ/m3), strong tensile strength (5.96 MPa) and sufficient elongation (115 %). At the same time, the self-healing DA-CWPU film can be recycled through solution casting. The sustainable castor oil-based waterborne polyurethane can be used as finishing agents for leather products, which realizes repeatedly self-healing in case of surface damage, greatly increasing the service life of the material and mechanical properties, providing a new approach for the development of mechanically robust self-healing materials.

Ecological risk assessment of castor oil based waterborne polyurethane: Mechanism of anionic/cationic state selective toxicity to Eisenia fetida

Cationic and anionic castor oil-based waterborne polyurethanes (C-WPU/A and C-WPU/C) have great potential for development in agriculture. However, it is still unclear whether these polyurethanes are harmful or toxic to soil fauna. Based on multilevel toxicity endpoints and transcriptomics, we investigated the effects of C-WPU/A and C-WPU/C on earthworms (Eisenia fetida). The acute toxicity results showed that C-WPU/A was highly toxic to the earthworms, whereas C-WPU/C was nearly nontoxic. C-WPU/A significantly affected the body weight, burrowing ability and cocoon production rate of earthworms compared to C-WPU/C. After exposure to C-WPU/A, the results showed accumulation of reactive oxygen species (ROS), abnormal peroxidase activity, and increased malondialdehyde levels. Additionally, more serious histopathological damage was observed in earthworms, such as epidermal damage, vacuolization, longitudinal muscle disorganization, and shedding of intestinal epidermal cells. At the cellular level, C-WPU/A induced more severe lysosomal damage, DNA damage and apoptosis than C-WPU/A. C-WPU/A made more differentially expressed genes and considerably more enriched pathways at the transcriptional level than C-WPU/C. These pathways are largely involved in cell membrane signaling, detoxification, and apoptosis. These results provide an important reference for elucidating the selective toxicity mechanisms of C-WPU/A and C-WPU/C in earthworms.

Effect of adding curcumin on the characterization of castor oil-based waterborne polyurethane coating

BackgroundThis study investigates the use of curcumin as a hydroxyl chain extender in polyurethane (PU) films, which not only absorbs ultraviolet (UV) light but also acts as a polymeric dye. It evaluates the lightfastness of these films and assesses their potential for wood coating applications. MethodsCurcumin-based waterborne PU (CPU) resins were prepared by the prepolymerization method using EDA (Ethylenediamine)/curcumin molar ratios of 9/1, 8/2, 7/3, 6/4, and 5/5. The CPU film was analyzed for its transparency, thermal stability, mechanical strength, and water absorption characteristics. In particular, the wood coating performance and lightfastness of the CPU resin were investigated. Significant findingsThe results indicate that higher curcumin content results in an increased proportion of hard segments and hydrogen bonds within the CPU film. Notably, when the EDA/curcumin molar ratio is set to 8/2, the CPU resin exhibits the highest molecular weight, particle size, and cross-linking density, thereby enhancing its tensile strength, Young's modulus, and storage modulus. The results demonstrate the CPU film's ability to absorb UV light, thereby increasing its resistance to light exposure and causing significant color changes in lightfastness tests. CPU resin holds promise for applications as a lightfast yellow coating and a light-sensitive color change indicator.

Synthesis and Application of Silane-Modified Castor Oil-Based Waterborne Polyurethane as a Fluorine-Free and Durable Water Repellent

Synthesis and Application of Silane-Modified Castor Oil-Based Waterborne Polyurethane as a Fluorine-Free and Durable Water Repellent

A Novel Polyfunctional Polyurethane Acrylate Derived from Castor Oil-Based Polyols for Waterborne UV-Curable Coating Application.

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared into castor oil-based waterborne polyurethane acrylate emulsion, and finally, a series of coating materials were prepared under UV curing. The results showed that with the increase in MACOG content, the glass transition temperature of the sample was increased from 20.3 °C to 46.6 °C, and the water contact angle of its surface was increased from 73.85 °C to 90.57 °C. In addition, the thermal decomposition temperature, mechanical strength, and water resistance of the samples were also greatly improved. This study not only provides a new idea for the preparation of waterborne polyurethane coatings with excellent comprehensive properties but also expands the application of biomass material castor oil in the field of coating.

Realization of customizable performance castor oil-based waterborne polyurethane antiseptic coatings via arbutin

The utilization of green and sustainable bio-based resources gets more important owing to the increasing shortage of petrochemical resources. Arbutin (AT) was considered to belong to a class of renewable polyhydroxy compounds due to its unique molecular structure. Hence, a molecular structure design strategy was employed to incorporate AT and castor oil into the backbone of anionic waterborne polyurethan (WPU). The effect of the AT content on the characteristics of WPU dispersion and casting film was thoroughly investigated. The result showed that the WPU films had excellent transparency, mechanical (the tensile strength was 28.4 MPa, the toughness was 34.3 MJ/m3), and thermodynamic properties, surpassing most current vegetable oil-based WPU systems. Notably, the WPU-AT20 film could pull target 18722 times its own weight, which could be ascribed to the cooperative effects of abundant rigid rings, H-bonds, and a higher physical crosslink density in systems. The Tg values of the WPU films were adjusted to range from 13.47 °C to 63.40 °C. The maximum value of Tg was, in particular, outstanding at present reported systems. Intriguingly, the WPU films still exhibited prominent anti-corrosion performance towards Q235# iron after severe weather conditions of outdoor storage for 4 months. The objective of this research was to offer simple and feasible strategies for preparing eco-friendly WPU coatings with excellent anti-corrosion performance.

Novel multifunctional highly crosslinked bio-based waterborne polyurethane networks modified via long fatty hydrophobic side chains

The mechanical properties and water resistance of castor oil-based waterborne polyurethane are mutually limited due to the presence of a hydrophilic chain extender. Herein, Arbutin (AT) was used as a crosslinking agent, and benzimidazole (CR-455) was utilized as an ultraviolet absorber, sustainable long fatty hydrophobic chain extenders, sorbitan monooleate (SP), glycerol laurate (GML), glycerin monostearate (GMS), and trimethylolpropane monooleate (TPM), were introduced into castor oil-based waterborne polyurethane (CWPU) backbones through molecular structure design respectively. Subsequently, the amount of SP was changed to prepare a series of waterborne polyurethane dispersions, and their emulsion and film properties were thoroughly investigated. The finding showed that the incorporation of long fatty hydrophobic chain extenders led to an increase in crosslinking density, thereby endowing CWPU films with good mechanical properties, water resistance, and anti-corrosion efficacy. Moreover, the bio-based content in the CWPU film had reached an impressive 90.9 %. The addition of SP content resulted in a gradual improvement in the mechanical properties, water resistance, and corrosion resistance of CWPU-SP films. When the SP content was 40 %, due to the high strength of hydrogen bonds and the density of crosslinking in systems, the tensile strength, toughness, water absorption rate, and corrosion protection efficiency of the CWPU-SP40 film reached 18.1 MPa, 20 MJ/m3,7.7 %, and 98.47 %, respectively. Particularly, the prepared transparent CWPU films exhibited complete UV shielding. This work would pave the way for the application of bio-based waterborne polyurethanes in high-performance coatings, such as anti-corrosion and sunscreen.

Antibacterial castor oil-based waterborne polyurethane/gelatin films for packaging of strawberries

Gelatin films for food packaging have gained popularity due to their affordability, strong renewability, and high biodegradability. However, pure gelatin film has poor stretch ability, moisture-sensitive, and no antibacterial properties, which limits its use in food industry. In this work, we effectively grafted quaternary ammonium groups onto a novel castor oil-based waterborne polyurethane (CWU). Gelatin was mixed with carious concentrations of CWU to create composite films. The mechanical properties, thermal stability, water permeability and oxygen permeability of these composite films improved dramatically with the increase of CWU concentration. The composite films demonstrated good inhibitory effect on Escherichia coli and Staphylococcus aureus due to the antibacterial capabilities of quaternary ammonium compound. The shelf life of the strawberry packaged in the composite film is extended to more than 6 days. Therefore, the new CWU mixed with gelatin could serve as an alternative food packaging material.

Castor oil-based waterborne polyurethane/tunicate cellulose nanocrystals nanocomposites for wearable strain sensors

In this study, tunicate cellulose nanocrystals (TCNCs) were introduced into castor oil-based waterborne polyurethane (WPU) to prepare bio-based nanocomposites through a simple solution blending method. The effect of TCNCs content on the particle size and stability of the composite dispersions, as well as the thermophysical and mechanical properties of the composite films were studied and discussed. The unique structure and properties of TCNCs, such as high crystallinity, large aspect ratio and high modulus, not only greatly improved the storage stability of WPU, but also showed significant reinforcing/toughening effects and excellent compatibility to WPU. By drip-coating silver nanowires (AgNWs) on the surface of the composite films, the flexible strain sensors were fabricated, which showed excellent sensitivity in monitoring human movement.

Curcumin-based waterborne polyurethane-gelatin composite bioactive films for effective UV shielding and inhibition of oil oxidation

Introducing natural products to obtain ultraviolet (UV) shielding materials for inhibiting the photo-oxidation of oily foods is environmentally friendly food technology. Instead of traditional physical mixing, curcumin was introduced into castor oil-based waterborne polyurethane as a chain extender and compounded with gelatin for bioactive composite films. With the increase of curcumin-based waterborne polyurethane (CWP), the film with 10 wt% CWP achieved nearly complete ultraviolet shielding. The swelling index and water solubility were reduced by 800% and 12.93%, respectively. The tensile strength and elongation at break increased by 183% and 114%, respectively. In addition, CWP enhanced the antioxidant activity of curcumin in water system by 52.10% and reduced the oxidation degree of soybean oil by 62.03–87.84%. This work provides a new idea for compounding natural active small molecules with polymers. • Curcumin was introduced into the waterborne polyurethane as a chain extender. • CWP was compounded with gelatin to obtain antioxidant packaging film WGA. • A small amount of CWP can achieve high transparency and complete UV shielding. • Water resistance,mechanical properties and antioxidant activity were optimized. • WGA film could effectively inhibit the photo-oxidation process of soybean oil.

Improving the property of castor oil-based waterborne polyurethane by polyhydroxy sapium sebiferum oil as crosslinking agent

In this paper, the sapium sebiferum oil-based polyols (SOP) were prepared by thiol-ene photo-click reaction with mercaptoethanol and inedible sapium sebiferum oil with high iodine value. The molecular structure and hydroxyl values of the SOPs were determined. Then, modified castor oil based waterborne polyurethane was prepared by using SOP, castor oil and isocyanate as raw materials. The particle size and the chemical structure of the emulsions were characterized. Anti-graffiti properties, water contact angle, mechanical properties and thermal properties of the films were tested. When the mass ratio of the SOP to castor oil increased, the water contact angle of the modified film increased by nearly 20°, and it showed good anti-graffiti performance, which can be erased by dry bumf without leaving trace after being written by marker. In addition, the temperature of 50% weight loss of modified film increased by 12 °C and the tensile strength and elongation at break can be improved 2.2 and 2.8 times than before, respectively, which may be related to the addition of crosslinking in the polyurethane by polyhydroxy SOP.

Flexible decorative wood veneer with high strength, wearability and moisture penetrability enabled by infiltrating castor oil-based waterborne polyurethanes

In this study, a simple vacuum impregnation process was proposed to infiltrate castor oil-based waterborne polyurethane (PUDs) into three types of rift cut wood veneers for developing flexible decorative wood veneers (FDWVs). The effect of PUDs with different emulsifier , hydroxyl/isocyanate molar ratio , and solid content on the flexibility, mechanical properties, micromorphology, wearability, water resistance, and thermomechanical properties of the FDWVs from cationic PUDs were investigated systematically. It is found that the cationic waterborne PUDs demonstrated easier impregnation and better improvement in flexibility than anionic waterborne PUDs. FDWVs impregnated with cationic PUDs has better flexibility and strength. The flexibility of FDWVs improved about 16–24 time, the flexible basswood veneers (FBW) can be rolled with 0.5 mm diameter steel bars without cracking, which was much better than the market requirements for the decorative wood veneers. In addition, the incorporation of cationic PUDs improved the tensile strength of FDWVs by 4–6 time in transverse and by 2–3 time in longitudinal direction . The resulting FDWVs demonstrated excellent water resistance and good breathability characteristics for surface decorative materials, which allow wood-based panels to adjust indoor humidity through moisture absorption and desorption. In brief, environmentally friendly flexible decorative wood veneers with enhanced flexibility and strength, good water resistance, excellent wearability, and good breathability were produced through a simple and energy-efficient method without hot-pressing and pretreatment processes, which provides a novel process for preparing FDWVs and enriches the variety of decorative materials. • A green flexible decorative natural wood veneer (FDWVs) was firstly prepared. • The flexibility of FDWVs improved by 16–24 time with a fracture diameter of 0.5 mm. • The tensile strength of FDWVs increased by 4–6 time in transverse direction. • The FDWVs demonstrated excellent water resistance, breathability, and wearability.

Preparation of degradable castor oil-based waterborne polyurethane with tannic acid as crosslinking agent and its application on leather surface coating

In recent years, the types and quantities of polyurethane products have increased day by day. However, traditional petroleum-based water-based polyurethanes not only have the problem of difficult waste disposal, but also accelerate the depletion of petroleum materials. Herein, an eco-friendly polymer was successfully prepared by introducing tannic acid (TA) into castor oil-based waterborne polyurethane (WPU). The effects of the incorporation of TA, a bio-based material, on the particle size of the resulting polyurethane (PU) dispersion, and the thermal performance, mechanical properties, and hydrophobicity of PU membranes were systematically investigated. Finally, ATR-FTIR and SEM of cured films after degradation were measured to characterize the degradation ability of the membranes. It was found that the tensile strength of the samples is improved from 12.67 to 19.57 MPa with the TA content increasing from 0 to 1.5%, nevertheless their elongation at break declines from 306.51 to 237.12%. A noteworthy increase in the glass transition temperature (Tg) was exhibited by using DSC and DMA for the resulting PU films with increasing the TA content. Besides, the improvement in the water absorption of the blend films decreases from 14.5 to 10.2% according to the advantage of TA increasing the degree of cross-linking of the system. After 120 days of degradation, it can be seen that the urethane bond and the aliphatic ester bond played a vital role in the degradation process through the infrared of the degraded films. At the same time, the introduction of TA improves the degradation performance of WPU films. What is more, the application of WPU dispersions containing tannins on the leather surface shows excellent comprehensive performance, which means that WPU dispersions have potential applications as leather finishing agents. This work takes advantage of two kinds of bio-based materials, the mass of bio-based materials accounts for 57% of the total mass, which not only shortens the utilization of petroleum resources, but also effectively resolved the problem that poor quality of castor oil-based WPU and traditional waste is difficult to degrade, improving the commercial value of castor oil-based PU.

Nanocelluloses Reinforced Bio-Waterborne Polyurethane.

The aim of this work was to evaluate the influence of two kinds of bio- nano-reinforcements, cellulose nanocrystals (CNCs) and bacterial cellulose (BC), on the properties of castor oil-based waterborne polyurethane (WBPU) films. CNCs were obtained by the acidolysis of microcrystalline cellulose, while BC was produced from Komagataeibacter medellinensis. A WBPU/BC composite was prepared by the impregnation of a wet BC membrane and further drying, while the WBPU/CNC composite was obtained by casting. The nanoreinforcement was adequately dispersed in the polymer using any of the preparation methods, obtaining optically transparent compounds. Thermal gravimetric analysis, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, dynamical mechanical analysis, differential scanning calorimetry, contact angle, and water absorption tests were carried out to analyze the chemical, physical, and thermal properties, as well as the morphology of nanocelluloses and composites. The incorporation of nanoreinforcements into the formulation increased the storage modulus above the glass transition temperature of the polymer. The thermal stability of the BC-reinforced composites was slightly higher than that of the CNC composites. In addition, BC allowed maintaining the structural integrity of the composites films, when they were immersed in water. The results were related to the relatively high thermal stability and the particular three-dimensional interconnected reticular morphology of BC.

Long-lasting repellent activities of eco-friendly polyurethane system for controlled citral against melon fly

Using plant essential oil instead of chemical pesticides to control melon fly (Bactrocera cucurbitae (Coquillett)) is still a great challenge in agricultural practices, which must effectively slow down the volatility rate of plant essential oil. In this study, citral as a natural plant essential oil was blended with environmentally friendly castor oil based waterborne polyurethane (PU). The interaction, chemical resistance, adhesion property and sustained release behavior of the composites with different citral content were clarified, and the efficacies against the melon fly under field conditions were explored. The results indicated that the composites prepared exhibited excellent adhesion behavior on bitter gourds (Momordica charantia L.) even under rainfall washing, meanwhile the chemical resistance of composites could be tailored via controlling citral content. Low citral content composite films could be washed off by alcohol without worrying about the safety of that on crops. The composite prepared exhibited long-lasting repellent behavior against melon fly. The composite can be prepared via a simple technology and low cost, which has great value for plant essential oil applied in agriculture and can provide a new approach for melon fly control.

Semi-interpenetrating polymer networks prepared from castor oil-based waterborne polyurethanes and carboxymethyl chitosan

A series of vegetable oil-based waterborne polyurethane composites were prepared through construction of novel semi-interpenetrating polymers network using carboxymethyl chitosan (CA) as the secondary polymer phase. The effects of CA contents on storage stability, and particle size distribution of the composite dispersions and thermal stability, mechanical properties and surface wettability of composite films were investigated and discussed. The results showed that the composite dispersions displayed excellent storage stability and the biomass contents of resulting films were high up to 80 %. A significant increase in crosslinking density and glass transition temperature of the composite films were observed as the CA contents increased, which was attributed to the increasing hard segment of films and strong hydrogen bonding interaction between polyurethanes and CA. This work provided a simple method to tailor the performance of environmentally friendly vegetable oil-based waterborne polyurethane, which could find application in the field of coatings, adhesives, ink and so on.

Synthesis of Castor Oil‐Based Waterborne Polyurethane with Improved Properties via Adjusting PBA/CO Soft Segment Ratio

AbstractIn this study, dimethylol propionic acid (DMPA) and ethoxylated polymer diol (N120) are incorporated as composite hydrophilic groups to synthesize a series of castor oil‐based waterborne polyurethane (CWPU) nano‐emulsions. The properties of the nano‐emulsions with different ratio of polybutylene adipate (PBA) and castor oil (CO) soft segments as well as their film are investigated systematically. Fourier infrared spectroscopy (FTIR) confirms that CO was successfully introduced into the waterborne polyurethane (WPU) structure. The result indicates that the maximum contact angle of the film is 75.51° with a 7/3 molar ratio of PBA/CO. Thermal Gravimetric Analyzer (TGA) and Dynamic thermomechanical analysis (DMA) tests show that the thermal stability of the films has gradually improved with the increase of castor oil content. The content of castor oil in CWPU also affects the mechanical properties of the film. The tensile strength of the film reaches 23.2 MPa, and the elongation at break is 1460.7 %, when the molar ratio of PBA/CO is 9/1. Atomic force microscopy (AFM) is used to express the surface morphology of CWPU films. The films surface become rougher due to the introduction of CO. This work combines castor oil and water‐based systems to provide a relatively simple preparation method to synthesize CWPU nano‐emulsions, which can be used in environmental protection coatings and adhesives, and has broader application prospects.

Eco-Friendly Castor Oil-Based Delivery System with Sustained Pesticide Release and Enhanced Retention

The deposition of pesticides and their retention on plant surfaces are critical challenges for modern precision agriculture, which directly affect phytosanitary treatment, bioavailability, efficacy, and the loss of pesticides. Herein, a novel and eco-friendly waterborne polyurethane delivery system was developed to enhance the spray deposition and pesticide retention on plant surfaces. More specifically, biobased cationic and anionic waterborne polyurethane dispersions were synthesized from castor oil. Both cationic and anionic polyurethane dispersions exhibited remarkable microstructural, amphiphilic, and nanoparticle morphologies with a core-shell structure that served to encapsulate a biopesticide (azadirachtin) in their hydrophobic cores (WPU-ACT). The results indicated that the cationic WPU-ACT carriers exhibited a better sustained release behavior and a better protective effect from light and heat for azadirachtin. In addition, the simultaneous spray of anionic and cationic WPU-ACT significantly enhanced the spray deposition and prolonged the retention of pesticides due to the reduced surface tension and surface precipitation induced by the electrostatic interaction when two droplets with opposite charges come into contact with each other. A field efficacy assessment also indicated that the simultaneous spray of anionic and cationic WPU-ACT could control the infestation of brown planthopper in rice crops. Castor oil-based waterborne polyurethanes in this study work as an efficient pesticide delivery system by exhibiting enhanced deposition, rainfastness, retention ability, protection, and sustained release behavior, holding great promise for spraying pesticide formulations in modern and environmentally friendly agricultural applications.

Development of azobenzene-functionalized eco-friendly waterborne polyurethane with halochromic property

An eco-friendly halochromic smart polymer was fabricated via covalently introducing azobenzene moieties into castor oil-based waterborne polyurethane. Infrared spectrum and thermogravimetric analysis have confirmed the successful incorporation of azobenzene moieties into polyurethane chains. The halochromic polymer undergoes color change from yellow to amaranth due to the structure shifting from azo form to hydrazine form at pH < 5, showing a visually detectable color difference with the naked eyes. It is also found that the color is reversible by neutralizing treatment and the switching process can be repeated more than 10 times. This eco-friendly halochromic polymer is expected to prepare wearable and visual pH sensor as environment, health and food monitors.

High bio-content castor oil based waterborne polyurethane/sodium lignosulfonate composites for environmental friendly UV absorption application

In this work, a series of castor oil-based waterborne polyurethane composites were prepared with different amounts of sodium lignosulfonate as functional filler. The effect of the sodium lignosulfonate contents on the particle size and storage stability of the polyurethane composite dispersions was studied and discussed. In addition, the thermo-mechanical, thermal stability, mechanical properties and UV absorption of the resulting polyurethane films were characterized. The composite dispersion exhibits excellent storage stability and the bio-content of the resulting composite films is high up to 70%. In addition, it was found that the tensile strength and storage modulus increased with increasing the sodium lignosulfonate contents due to enhancement effect from the rigid benzene ring structure of sodium lignosulfonate and good compatibility between polyurethane matrix and the filler. The introduction of sodium lignosulfonate into WPU matrix rendered the excellent UV absorption of the composites due to the conjugated structures of lignin macromolecular. This work provides a new simple method to prepare environmental friendly bio-based waterborne polyurethane composites, which could find widely application in the field of UV absorption coatings and sunscreen cream.