Cationic Waterborne Polyurethanes Research Articles

Synergetic improvement of flame retardancy and heat resistance of cationic waterborne polyurethanes by introducing a DOPO-containing flame retardant

The cationic waterborne polyurethanes (CWPU) exhibit excellent affinity towards various materials possessing negative surface charges owing to its positive charge. However, its limited heat resistance and flame retardancy greatly restrict its practical application. In this work, we synthesized a flame retardant, 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-hydroxyethoxyphenylene (DOPO-HQ-HE), and incorporated it into the skeleton of cationic waterborne polyurethanes to prepare flame-retardant cationic waterborne polyurethanes (CWPU-DHHxs). The obtained CWPU-DHHxs showed excellent flame retardancy, in which the LOI value of CWPU-DHH12 reached over 26.9 vol% and passed UL-94 V-0 rating. The findings showed that CWPU-DHHxs exhibited remarkable efficacy in both the vapor and condensed phase during combustion. Moreover, the incorporation of DOPO-HQ-HE led to a significant improvement in heat resistance performance by facilitating enhanced microphase separation. Meanwhile, the major comprehensive performance of CWPU-DHHxs, including emulsion storage stability, thermal stability, mechanical performance, and transparency were effectively preserved.

Correction: Stable emulsion of cationic waterborne polyurethanes with cellulose nanocrystals for enhanced nanocomposite performance

Correction: Stable emulsion of cationic waterborne polyurethanes with cellulose nanocrystals for enhanced nanocomposite performance

Stable emulsion of cationic waterborne polyurethanes with cellulose nanocrystals for enhanced nanocomposite performance

Stable emulsion of cationic waterborne polyurethanes with cellulose nanocrystals for enhanced nanocomposite performance

Preparation and characterization of cationic waterborne polyurethanes containing a star-branched polydimethylsiloxane

Preparation and characterization of cationic waterborne polyurethanes containing a star-branched polydimethylsiloxane

Robust Catechol Containing Cationic Waterborne Polyurethanes with Antibacterial, UV Protective, and Adhesive Properties

AbstractFunctional cationic waterborne polyurethanes (CWPUs) with environmental friendliness and excellent mechanical properties are widely desired in the materials industry. However, traditional modification methods such as molecular structure adjustment, crosslinking modification, and physical filling for polyurethane are overly complex and do not typically improve mechanical properties to the point of satisfying the stringent requirements for modern industrial materials. In this study, phenolic acid 3,4‐dihydroxybenzoic acid with a catechol structure is applied to neutralize the tertiary ammonium structure on the side chain of polyurethane for the facile preparation of CWPU materials. The effects of this neutralizer on the microstructure, mechanical properties, and functional performance of CWPU samples (e.g., antibacterial, ultraviolet protection, coating properties) are systematically investigated. The results indicate that the catechol structures of the neutralizer provide abundant hydrogen bonding reaction sites, which greatly improves the mechanical properties of the CWPU films with the maximum strength of 43 MPa and simultaneously 1241% elongation at break. Furthermore, catechol structure and cationic attribute endow the CWPUs with excellent adhesion to various substrates, strong ultraviolet protection performance, and antibacterial ability. The proposed approach can be used to prepare robust CWPUs with strong functional performance as highly effective, environmental‐friendly materials over a large scale.

Biodegradable cationic waterborne polyurethanes from poly(caprolactone)diol and trimethylol propane monooleate

AbstractBiodegradable cationic waterborne polyurethanes (WPUs) were successfully prepared using poly(caprolactone) diol as the soft segment. To improve the mechanical performance, adhesive strength and water resistance of the WPU films, different amounts of trimethylol propane monooleate (TMPM) containing biodegradable long‐branched aliphatic chains were incorporated in the PU structure. The T‐peel strength of WPU‐3 reached 42.8 N/25 mm, which was about 324% higher than that of WPU (10.1 N/25 mm) without TMPM. On the other hand, the elongation at break of WPU‐5 was 811%. On enhancing the TMPM content from 0 to 7.8 wt %, the surface tension decreased from 53.6 to 41.5 mN/m and the water contact angle of the WPU films increased from 52.4 to 81.0°, whereas the water absorption was observed to decrease from 15.6% to 9.6%. The fracture mechanism of the WPU films transformed from the brittle failure to the ductile fracture. The experiment results showed the cationic WPU modified by TMPM displayed excellent film‐forming property flexibility and adhesion, the surface tension of WPU dispersion and crystallinity of the resulting film were significantly reduced. For the first time, a biodegradable cationic WPU has been prepared by modification with TMPM, which can be employed for constructing the eco‐friendly biodegradable cationic WPUs.

A Healable and Mechanically Enhanced Composite with Segregated Conductive Network Structure for High-Efficient Electromagnetic Interference Shielding

HighlightsThe cationic waterborne polyurethanes microspheres with Diels-Alder bonds were synthesized for the first time.The electrostatic attraction not only endows the composite with segregated structure to gain high electromagnetic-interference shielding effectiveness, but also greatly enhances mechanical properties.Efficient healing property was realized under heating environment.It is still challenging for conductive polymer composite-based electromagnetic interference (EMI) shielding materials to achieve long-term stability while maintaining high EMI shielding effectiveness (EMI SE), especially undergoing external mechanical stimuli, such as scratches or large deformations. Herein, an electrostatic assembly strategy is adopted to design a healable and segregated carbon nanotube (CNT)/graphene oxide (GO)/polyurethane (PU) composite with excellent and reliable EMI SE, even bearing complex mechanical condition. The negatively charged CNT/GO hybrid is facilely adsorbed on the surface of positively charged PU microsphere to motivate formation of segregated conductive networks in CNT/GO/PU composite, establishing a high EMI SE of 52.7 dB at only 10 wt% CNT/GO loading. The Diels–Alder bonds in PU microsphere endow the CNT/GO/PU composite suffering three cutting/healing cycles with EMI SE retention up to 90%. Additionally, the electrostatic attraction between CNT/GO hybrid and PU microsphere helps to strong interfacial bonding in the composite, resulting in high tensile strength of 43.1 MPa and elongation at break of 626%. The healing efficiency of elongation at break achieves 95% when the composite endured three cutting/healing cycles. This work demonstrates a novel strategy for developing segregated EMI shielding composite with healable features and excellent mechanical performance and shows great potential in the durable and high precision electrical instruments.

Preparation and Properties of Biobased, Cationic, Waterborne Polyurethanes Dispersions from Castor Oil and Poly (Caprolactone) Diol

Biobased cationic waterborne polyurethanes (WPUs) were prepared using isophorone diisocyanate (IPDI), N-methyl diethanolamine (N-MDEA), polycaprolactone (PCL) diol, hydrochlotic acid (HCl), and 1,4-butanediol (BDO). To improve the mechanical performance and adhesive strength of the waterborne polyurethane films, different amounts of castor oil (CO) acting as a cross-linking agent were incorporated in the polyurethane structure. The structures of the waterborne polyurethanes were assessed by Fourier-transform infrared spectroscopy (FTIR). The combination of CO had a positive effect on the dispersion and stability properties of WPUs. WPUs containing higher content of CO demonstrated a remarkable enhancement in homogeneity among particles. The stable aqueous dispersion was obtained even when N-MDEA loading was as low as 3.2 wt%; a bonus of this low hydrophilic moiety was the excellent adhesive strength, whose T-peel strength could reach up to 36.8 N/25 mm, about 114% higher than that of WPU (17.2 N/25 mm) without any CO content. The elongation at break of CO7.40%-WPU was 391%. In addition, the fracture mechanism of the waterborne polyurethane films transformed from the brittle failure to the ductile fracture. The experiment results showed the CO-modified WPUs displayed excellent film-forming property, flexibility, and adhesion, which can be employed for constructing the eco-friendly, biodegradable, cationic, waterborne polyurethanes.

UV absorption, anticorrosion, and long-term antibacterial performance of vegetable oil based cationic waterborne polyurethanes enabled by amino acids

This study provides a simple method for tailoring the performance of the WPUs by employing amino acids as environmentally-friendly proton sources, which eliminates long-standing issues of WPUs, such as irritating odor, corrosiveness, and air pollution. • Novel WPU have been successfully prepared using amino acids as proton sources. • WPU ranging from flexible elastomers to tough plastics can be tailored by acids. • Tunability of hydrogen bonding confers UV protection and anti-bacterial to WPU. • Application of amino acid eliminates irritating odor, corrosiveness issues of WPU. Acids are traditionally used in the production of environmentally-friendly cationic waterborne polyurethane dispersions. However, the effect of their conjugate bases on the final properties of waterborne polyurethanes has been rarely explored. In this study, the effect of different acids in tailoring the performance of bio-based cationic waterborne polyurethanes has been reported. Polyurethane films ranging from flexible elastomers to tough plastics can be obtained, and their properties can be simply controlled by the selection of the acids. The tunability of the hydrogen bonding strength confers the resulting polyurethane films enhanced multi-function, such as UV absorption, anticorrosion properties, and long-term antibacterial performance. These results represent a significant advancement over traditional techniques, providing a simple strategy to tailor the performance of cationic waterborne polyurethanes, and offering environmentally-friendly amino acid substitutes for commonly used acids, such as acetic acid, HCl, or glycolic acid. The methodology described here eliminates long-standing issues of PUs, such as irritating odor, corrosiveness, and air pollution.

Enhanced Mechanical Properties and Functional Performances of Cationic Waterborne Polyurethanes Enabled by Different Natural Phenolic Acids

Tailoring the performance of waterborne polyurethanes through composition control and structural optimization to meet the highly diversified modern demands is still one of the primary challenges fa...

Synthesis and characterization of cathodic electrodeposition coatings based on octadecyl-modified cationic waterborne polyurethanes

Aimed at increasing the hydrophobicity of cathodic electrodeposition (CED) coatings based on cationic waterborne polyurethanes (WPUs), a series of cationic WPUs with hydrophobic octadecyl side chains were successfully synthesized by introducing 1-monostearoyl-rac-glycerol as a diol chain extender. ATR-FTIR spectra and SEM images showed the degree of phase separation between soft segments and hard segments of cationic WPUs clearly increased by incorporating octadecyl groups. The water contact angle and water absorption studies showed that the water-resistance property of modified CED coatings was obviously enhanced because of the incorporation of a low surface energy unit and the formation of a more sophisticated surface induced by hydrogen bonds. The International Standardization test of paints and varnishes revealed that the CED films possessed excellent hardness, adhesion, flexibility, and impact resistance. Optical transmittance tests showed that the sample films possessed excellent optical transmittance of about 90%, and meanwhile, the thermostability of the film was promoted.

Effects of molecular weight of hydroxyl telechelic natural rubber on novel cationic waterborne polyurethane: A new approach to water-based adhesives for leather applications

Renewable resource based cationic waterborne polyurethanes (cWPUs) have been prepared from hydroxyl telechelic natural rubber (HTNR) with a range of number average molecular weights (Mn) (2820, 1800, and 950 g mol−1), toluene-2,4-diisocyanate (TDI), N-methyl diethanolamine (NMDEA), and ethylene glycol (EG). The chemical structure of the cWPUs was confirmed by FT-IR and 1H NMR. Particle size and zeta potential of prepared cWPUs were also characterized by ZS nanosizer. By varying the levels of Mn of HTNR, the obtained cWPUs were stable with a milky blue appearance, forming yellowish films. The smallest particle sizes of 76.4 nm were achieved using Mn of HTNR of 2820 g mol−1 while zeta potential value ranges from 67 to 71 mV were observed with increasing Mn of HTNR. Lap shear testing of these WPUs indicates their potential in real cow leather adhesive applications, with the best adhesive result coming from cWPU based on an HTNR molecular weight of 1800 g mol−1. The results show the potential of natural rubber as a green adhesive material in suitable aqueous environments.

Synthesis of Cationic Waterborne Polyurethanes from Waste Frying Oil as Antibacterial Film Coatings

Cationic waterborne polyurethane (CWPU) was synthesized from waste frying oil and utilized as antibacterial film coatings. Waste oil-based monoglyceride was synthesized by the alcoholysis reaction of waste oil with glycerol, while CWPUs were prepared by esterification with methylenediphenyl 4,4′-diisocyanate (MDI) and bis(2-hydroxyethyl)dimethyl ammonium chloride (BHMAC) as an internal emulsifier. The effect of internal emulsifier contents on the chemical structures and properties of the obtained polyurethanes was studied. Bactericidal activity of the obtained polyurethanes toward Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was investigated using the time kill assay. CWPUs were successfully synthesized as confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT-IR). Effects of the internal emulsifier on particle size of CWPUs and mechanical properties of the resulting polyurethane films were investigated and measured by transmission electron microscopy (TEM). Particle size diameter of CWPUs ranged from 13.38 to 28.75 nm. The resulting polyurethane films were very pliable, with moderate adhesion and hardness. All films showed good resistance to water and diluted acid but poor resistance to dilute alkali. Obtained CWPUs provided excellent antibacterial activity, with efficiency increasing with increasing amount of BHMAC. Interestingly, antibacterial ability against S. aureus was more rapid than that against E. coli under similar conditions. Results offered an alternative utilization of waste frying oil as a sustainable raw material for the preparation of value-added polymers in the chemical industry.

Emulsion stability and water tolerance of cationic waterborne polyurethane with different soft segment ratios between trifunctional polyether and bifunctional polyester

A series of cationic waterborne polyurethanes (WPU) was prepared using isophorone diisocyanate (IPDI) as the hard segment and polyester diol (PE2348), polyether triol (ZC330) or their mixture as the soft segment. The effects of the content of PE2348 and ZC330, crosslinking density on the particle size and its distribution, stability of WPU emulsion and the thermosstability, mechanical properties of WPU membrane were investigated. The results indicated that the increase of PE2348 in the mixed soft segment contributes to inhibiting the hydration, and the average particle size of the emulsion decreased because of the same cause. However, the stickiness of the corresponding film was increased and the elasticity deteriorated too. Structure uniform and suitable hydrophilicity of soft segment contributed to the stability, and higher crosslinking degree will contribute to the water-impregnation resistance of cationic waterborne polyurethanes membrane. Moderate hydrophilicity of polyurethane molecules and uniform distribution of hydrophilic structure are beneficial to uniform dispersion of polyurethane and better emulsion stability. If the miscibility between soft segments and hard segments and between the different soft segments is better, water resistance of the membrane will be improved significantly.

Preparation and Application of Anionic and Cationic Waterborne Polyurethanes and Graphene-Cellulose Nanocrystal as an Antistatic Agent for Cashmere

The main purpose of this research work is to improve anti-static properties of Cashmere fabric by introducing application comprising anti-static agent by foaming which was made with cationic waterborne polyurethane and graphene-CNC. Cashmere fabric was cut into 10 pieces of sample cloth of 5 cm * 5 cm size, washed with acetone solution, and then dried in an oven at 60℃. Three forms of waterborne polyurethanes such as two forms of Cationic waterborne polyurethane (CWPU) and a form of Anionic waterborne polyurethane (AWPU) were synthesized. Cellulose nanocrystalline (CNC)/graphite powder solution with the ratio of 0.5/1, 1/1, 2/1 was prepared by ultrasonic probe stripping method, and the concentration of graphite powder was ensured to be 1 mg/ml. The fabric was treated with anionic and cationic WPUs foaming solution until the weight gain reached 2.5 - 3.5 wt%. After drying, the elastic cloth was foamed with graphene solution until the graphite content of the cloth was close to 10%, 20%, 40%, 60% respectively, and then dried for reserving. Characterization properties of pure graphite powder, pure CNC and graphene solution with different proportions of three components were tested by Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), Thermalgravitimetric analysis (TGA) and scanning electron microscopy (SEM). Take the original cloth, only WPU treated cloth and four clothes with different graphite content for the fabric performance test.

The study of cationic waterborne polyurethanes modified by two different forms of polydimethylsiloxane.

Two kinds of dimethylpolysiloxane, KF-6001 and X-22-176-DX, were used to modify polyurethane. The effects of KF-6001 and X-22-176-DX on the colloidal, physico-chemical and surface properties were studied for polydimethylsiloxane modified cationic waterborne polyurethanes (SiCWPUs). The chemical structures and the surface morphologies of the SiCWPUs are characterized via Fourier transform infrared spectrometry and scanning electron microscopy. The results showed that the addition of siloxane changes the structure and surface morphology of the polyurethane. The element distributions in the polymer films were tested via X-ray photoelectron spectroscopy, and the effect of the hydrophobicity of the surfaces of the polymer films of the cationic waterborne polyurethanes was demonstrated via water contact angle tests on the surfaces of the films. As the amount of siloxane added increases, the silicon content on the surfaces of the SiCPWU1 films increases from 0% to 17.92%, and the actual silicon content on the surfaces of the films was much larger than the theoretical value. Therefore, the hydrophobicity of the membrane surface increases sharply, and the contact angle increases from 63.0° to 105.3°. Dynamic mechanical analysis indicates that the introduction of polydimethylsiloxane into the cationic aqueous polyurethane chain increases microphase separation in the polymer films. Stress–strain data showed that the mechanical properties of SiCPWU1 films were better than those of SiCPWU2 films when the same amounts of PDMS were added.

Preparation and properties of hydroxyl‐terminated cationic waterborne polyurethanes for cathodic electrodeposition coatings

AbstractHydroxyl‐terminated cationic waterborne polyurethanes (HCWPUs) were synthesized using N‐methyldiethanolamine (N‐MDEA) as internal emulsifier and mixed with cross‐linker of nonionic waterborne blocked polyisocyanate (NWBI) to prepare cathodic electrodeposition (CED) coatings. The effects of N‐MDEA content, NCO/OH molar ratio, neutralization degree, and NWBI content on the performance of HCWPUs emulsion and relevant CED coatings were investigated. The results showed that 7.5 wt.% of N‐MDEA content, 0.9/1 of NCO/OH molar ratio, and 100% of neutralization degree were the optimal experimental parameter for synthesizing excellent performance HCWPUs. Incorporation of nonionic waterborne blocked isocyanate could significantly promote the hardness, adhesion, and solvent resistance of CED coatings without influencing the emulsion stability and coatings thermostability.

Bio-based cationic waterborne polyurethanes dispersions prepared from different vegetable oils

In this study, a series of bio-based polyols were prepared from olive, castor, corn, canola, rice bran, grape seed and linseed oil by thiol-ene photo-click reaction. The relationship between carbon-carbon double bonds in the backbone of vegetable oil fatty acid chains and the functionalities of the polyols was elucidated. The advantage and disadvantage between thiol-ene photo-click reaction and traditional methods for vegetable oil based polyols are summarized and compared. These bio-based polyols were used to prepare cationic waterborne polyurethane dispersions.With the increase of the vegetable oil based polyols’ hydroxyl values, the tensile strength, Young’s modulus, Tg, water contact angle of the waterborne polyurethane films increase from 1 to 11 MPa, 10 to 395 MPa, 23 to 50 °C and 38˚ to 46˚, respectively, but the elongation at break and thermal stability of them decrease. Thiol-ene photo-click reaction offers a bio-based platform to create a variety of waterborne polyurethanes that promises economic and environmental benefits.

Synthesis and characterization of novel natural rubber based cationic waterborne polyurethane—Effect of emulsifier and diol class chain extender

ABSTRACTNovel cationic waterborne polyurethanes (cWPU) were synthesized by step‐growth polymerization of hydroxyl telechelic natural rubber, molecular weight of 2800 g mol−1, toluene‐2,4‐diisocyanate, N‐methyl diethanolamine (NMDEA) as an emulsifier. The chemical structure of cWPU was confirmed by 1H‐nuclear magnetic resonance and Fourier transform infrared spectroscopy. The amounts of NMDEA and ethylene glycol under isocyanate (NCO) index of 100 on the properties of cWPU were studied. It was found that cWPU was stable under the concentration of NMDEA more than 1.50 mol and the particle sizes decreased with increasing of NMDEA content. Also, contact angle shows more hydrophilic materials by increasing of NMDEA. Extended cWPU was found in two ranges of nano size. Chain extender has strongly affected cWPU film formation, increasing of mechanical properties, and thermal properties. In addition, stress–strain curve and scanning electron microscopy image shows the change of behavior from soft elastic to ductile plastic by adding ethylene glycol. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45715.

Synthesis of stable cationic waterborne polyurethane with a high solid content: insight from simulation to experiment

We combined micro-simulation and macro-experiments to explore the structure–morphological–property relations of cationic waterborne polyurethanes with a high solid content.