Anionic Polyurethane Dispersions Research Articles

Preparation of efficient and eco‐friendly solid polymer electrolyte based on anionic polyurethane dispersion, polyethylene oxide, and halloysite nanotube

AbstractWith the ever‐increasing need for energy storage devices with high energy density, lithium (Li) metal anodes have been revisited. Due to the high reactivity of Li metal and the safety issues associated with liquid electrolytes, solid polymer electrolytes (SPEs) have gain attention. Polyethylene oxide (PEO) with the highest ionic conductivity (σ) among the polymers faces serious problems. The inability to meet the practical limit of σ due to its high crystallinity, and its low thermomechanical stability above its melting temperature, have limited its large‐scale application. In this research, anionic polyurethane dispersion (PUD) based on poly (ε‐caprolactone) (PCL) was synthesized and different PUD:PEO compositions was prepared using water as a solvent. Halloysite nanotube (HNT) was also used to improve the ionic conductivity by providing a new pathway for conducting lithium ions in the composition. The results corroborated that the presence of PUD stabilized the storage modulus of the host polymer above Tm of PEO. The ionic nature of the selected PUDs resulted in a transference number of 0.59 and the presence of HNT increased this value to 0.72. The presence of HNTs also led to a significant increase in σ by about three times compared to the control sample.

Synthesis of epoxy resin-based aqueous polyurethane and application to polyester-cotton fabric finishing

In this work, epoxy resin (EP)-based aqueous polyurethane (PU) anionic PU dispersion was synthesized by the prepolymer and self-emulsification method. The PU prepolymer was first synthesized to serve as seeds. Then, trimethylolpropane and A-type EP (E-51) were introduced into it, followed by neutralization and emulsification reactions, and, finally, it formed a crosslinking network structural waterborne PU emulsion. The effect of epoxy contents on the particle size, rheological properties, storage stability, thermal stability, mechanical properties, and hydrophilicity of the resulting PU films was systematically investigated. The results showed that the PU dispersions displayed excellent storage stability and crosslinking density, and the glass transition temperature of the composite films was increased. The properties of self-made epoxy-modified polyurethane emulsion and polyester-cotton fabric before and after finishing were tested. The wrinkle resistance, hydrophobicity, and strength of the finished polyester/cotton fabric are improved, and it exhibits better color fastness to washing and rubbing.

Citric acid/glycerol ester, a backup of 2, 2-bis(hydroxymethyl)propionic acid and biobased synthesis of anionic polyurethane dispersion

Nowadays biobased anionic polyurethane dispersions (PUDs) have been widely used in automotive, paints, coatings etc., but the strategies for achieving optimum properties are still highly challenging. Contrary to current knowledge, here glycerol ester of citric acid (GECA) was used as an internal biobased emulsifier for preparing high performance anionic PUD. Density functional theory (DFT) calculations revealed that GECA has comparable reactivity to the conventional bis(hydroxymethyl)propionic acid. GECA was prepared by an esterification reaction between citric acid and glycerol. The PUD was obtained by reacting GECA with isophorone diisocyanate in the presence of poly(ε-caprolactone) diol and monoglyceride of castor oil using a prepolymerization process. Films obtained from this PUD exhibited outstanding elongation at break (1469–1833%), good tensile strength (6.39–10.58 MPa), high toughness (65.47–95.71 MJm−3), adhesive strength (W-W) (13.06–43.29 kPa), thermal stability (330–385 °C), transparency (59–83%) and chemical as well as UV-resistance. PUD films also showed biodegradation under the exposure of Pseudomonas aeruginosa and Bacillus subtilis bacterial strains. Thus, the synthesized PUD is not only an eco-friendly material, but it has also high potential for industrial applications.

Synthesis and characterization of transparent 1-package PUD based on castor oil and polyethylene glycol

In this study, a series of 1-package anionic polyurethane dispersions (PUDs) based on isophorone diisocyanate (IPDI), polyethylene glycol (PEG), and castor oil (CO) were prepared. The fourier transform infrared spectroscopy (FTIR) was conducted to ensure that the reaction was completed. The thermal analyses like dynamic mechanical thermal analysis (DMTA) indicated that the rise in NCO/OH ratio increased the glass transition temperature. Physico-mechanical properties such as tensile strength and hardness increased by increasing the NCO/OH ratio, but elongation at break decreased. Besides, the dispersion at pH = 8.4, pH = 9.1, and pH = 9.8 had the average particle size of 961, 681, and 494 nm and zeta potential of -0.549, -2.75, and -3.72 respectively. This work provides a new way to synthesize environmentally-friendly transparent 1-package PUDs with essential properties like higher tensile strength and unlimited pot life for various applications such as coating, leather, wood products, and so on in comparison to 2-package ones.

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.

Modified bitumen emulsion by anionic polyurethane dispersion nanocomposites

Different materials and compounds were used for improving mechanical and rheological properties of bitumen. Replacing the traditional bitumen by emulsion bitumen is increasing due to reduced environmental pollution. In recent years, emulsion bitumen modification has been considered to obtain higher efficiency bitumen with water-dispersible polymers. For this purpose, this study intends to investigate the modification of emulsion bitumen using water-dispersible anion polyurethane nanoclay nanocomposite. Since the polymer elasticity property plays an important role in bitumen modification and its properties, anionic polyurethane with different elastic properties was prepared by changing its structure, and its effects on modifying bitumen emulsion were investigated. Preliminary tests of bitumen properties and rheological behaviour analysis were performed on the prepared samples. The results of the tests showed that the penetration-modified bitumen decreased and softening point increased. As the structure of modifier changes, the rheological behaviour of bitumen is improved and changes from viscous to elastic one.

Aqueous anionic polyurethane dispersions from castor oil

In this study, dimethylol propionic acid (DMPA) and dimethylol butanoic acid (DMBA) were employed to synthesize the castor oil-based waterborne polyurethane dispersions (PUDs). The effects of these two emulsifier and their contents on the properties of the PUDs as well as their films were investigated systematically. The results show that as the emulsifiers contents increase, the particle size and zeta potential of the PUDs decrease while the tensile strength of the resulting PU films increase but thermal stability, water and chemical resistance decrease. The PUDs from DMBA exhibit smaller particle size than those from DMPA and the films from the former show higher tensile strength, higher elongation at break but lower thermal stability, lower water resistance. This work provides a new way to synthesize environmental friendly bio-based waterborne polyurethanes whose properties can be tuned according to their application, such as coating, ink, leather, styling products and so on.

Aqueous Polyurethane Dispersions - Sodium Alginate Based Blends and Hydrogels

The film forming binary polyurethane-alginate blends and based hydrogels, containing different alginate content, were prepared by blending of anionic polyurethane dispersions (APD) and aqueous sodium alginate (SA) solution. Binary blends of APD and SA were cast in film form from mixed aqueous polymer solutions by solvent evaporation. Post-treatment of as-cast films with CaCl2 leaded tot he hydrogels formation. The thermal stability, thermal transition, water-swelling, mechanical properties and gas permeance for O2 and CO2 of two kinds of films were examined according to alginate content. Irrespective of composition, blend samples gave a single glass transition temperature (Tg), indicating the formation of thermodynamically miscible phase. The shift of Tg in hydrogels to the higher temperatures indicated the possible simultaneous occurrence of a chelate complexation of SA with Ca+2 cations, cross-links between polyurethane chains, having carboxylate anions, with Ca2+ cations, and interactions between SA and anionic polyurethane, resulting in the formation of an semi-interpenetrating network structure. The relationships between the films structure, their physicochemical properties and alginate content have been discussed.

Migration behavior of anionic polyurethane dispersion during infiltration and redistribution in sand

The migration behavior of anionic polyurethane (APU) dispersion (APUD) was investigated by using a newly established method, which is based weight measurement.

Waterborne polyurethane based starch containing materials: Preparation, properties and study of degradability

Abstract New starch-containing aqueous anionic polyurethane dispersions (APU/St) were prepared by the introduction of an aqueous starch solution into an anionic oligourethane solution and by the combination of the chain extension and dispersion stages. A fundamental difference between the APU/St dispersions and mechanical mixtures of anionic polyurethane dispersions and starch (APU + St), which manifests itself in a high aggregate stability and ability to form solid films, has been proved. APU/St based films display higher tensile strength in comparison with St and are characterized by increased values of elongation at break, degree of hydrophilicity, and significantly enhanced ability to undergo an acid/alkaline hydrolysis compared with the APU matrix. The adhesion of microorganisms Bacillus subtilis to the APU/St surface, which is the first step and determining factor of biodegradation, exceeds those of the APU matrix. The introduction of St into the APU structure resulted in the formation of amorphous polymer–polymer microdomains, i.e. an integrated system formed due to the presence of both the covalent and the hydrogen bonds between its ingredients. This predetermines the degradation of the APU/St systems as a whole, unlike the mixed APU + St films.

Phase morphology of hydrolysable polyurethanes derived from aqueous dispersions

Biodegradable polyurethanes are an interesting alternative to many applications that involve plastics since they can minimize environmental problems caused by the low rates of natural degradation of synthetic polymers. In addition, since waterborne polyurethanes are based on aqueous dispersions, they restrict the use of organic solvents during processing and application of the polymer, thus contributing furthermore to reduce environmental damage. In this work, aqueous anionic polyurethane dispersions (PUD) with tailorable susceptibility for hydrolysis were synthesized by progressively replacing polypropylene glycol (PPG) with a biodegradable polycaprolactone diol (PCL) as soft segments. The hard segments were formed by extending isophorone diisocyanate (IPDI) with hydrazine (HZ). Dimethylol propionic acid (DMPA) was used as ionic center and triethyl amine (TEA) as neutralizer. The degree of phase separation was evaluated mainly by infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS). The results indicated that phase separation between hard and soft segments of poly(ester–urethane) is more significant than that of poly(ether–urethane). Data obtained from SAXS experiments indicated that phase separation within soft domains can also be present in samples containing both polyester and polyether soft segments. Hydrolytic degradation of the polymers in buffer solution of pH 7.4 and alkaline solution was performed as an initial test. The results showed that the fraction of polyester soft segments in the polyurethanes can be used to tailor the susceptibility of the materials to hydrolytic attack. Polyurethanes having higher contents of polyester were more promptly hydrolytically degraded than polyurethanes containing only polyether segments.

Surface modification with waterborne fluorinated anionic polyurethane dispersions

AbstractWaterborne fluorinated anionic polyurethane dispersions (FAPUDs) were synthesized from tris(6‐isocyanatohexyl) isocyanurate, N‐ethyl‐N‐2‐hydroxyethyl‐perfluorooctanesulfonamide, poly(oxytetramethylene glycol) (PTMG), dimethylolpropionic acid (DMPA), hexamethylene diisocyanate, 1,4‐butanediol, and two different neutralizing agents (triethylamine and sodium carbonate). Waterborne polyurethane dispersions (PUDs) were synthesized from isophorone diisocyanate, PTMG, DMPA, and ethylenediamine as chain extenders. The particle size of the FAPUDs, based on the fluorine content and degree of neutralization (DN), was measured with dynamic light scattering. So that the surface modification and morphology variations of the PUDs through the addition of the FAPUDs could be observed, the surface energy and thermal properties of the blending films [fluorine PUD mixtures (FPMs)] were measured with contact‐angle analysis and differential scanning calorimetry. The particle size of the FAPUDs increased as the fluorine content in the FAPUDs increased and decreased as the DN increased. The surface energy of the FPM films made from the blending of the FAPUD T series (neutralization with triethylamine) gradually decreased above the critical fluorine concentration (0.02797 wt %). However, for the blending of the FAPUD 25Na series (neutralization with sodium carbonate), the surface energy increased above the critical fluorine concentration (0.02797 wt %) because of the increase in Na salts. The FAPUDs showed the native thermal behavior of the fluorine. However, the thermal properties of the blending films were like those of pure PUDs. This showed that the morphology of the PUDs was rarely unchanged when the FAPUDs were added. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3322–3330, 2002

UV curable polyurethane-based microspheres

Radiation curable polyurethane-based microspheres were prepared by modifying conventional procedures for preparing anionic polyurethane dispersions. Vinyl groups were introduced to the side chains and the ends of the polyurethane main chains. Photoinitiators and multifunctional acrylate oligomers were incorporated into each microsphere. The curing behavior of the films obtained from these microspheres under UV were studied. The MEK resistance of UV cured films without multifunctional acrylate oligomers was raised when the content of vinyl groups is above a certain threshold value. The effect of the incorporation of multifunctional acrylates oligomers on MEK resistance was observed. This effect was remarkable at low UV irradiation intensity. The curing behavior of the films was followed by real time FT-IR spectroscopy. The accelerating effect of the incorporation of multifunctional acrylates became striking particularly at the early stage of curing process. Multifunctional acrylates were found to be effective in raising the extent of the conversion of the double bonds. The curing behavior under UV irradiation was compared with that under EB irradiation.

Investigation of the particle surface of anionic polyurethane dispersions with COO−‐groups

AbstractPolyurethanes, containing both terminal and nonterminal COOH ‐ groups, were synthesized from poly(propylene oxide), 1,2,4‐benzenetricarboxylic acid anhydride and 1,6‐hexamethylene diisocyanate. Aqueous dispersions were prepared from the acetonic solutions after partial neutralization.The concentration of carboxylic groups present before the formation of the dispersion was determined quantitatively by potentiometric titration with methanolic KOH in nonaqueous solution.The determination of the titratable COOH‐ and COO−‐groups after dispersion formation was carried out by conductometric or potentiometric titration with NaOH or HCl. It was found, that all COOH‐ and COO−‐groups present in the system could be detected in the dispersion. This indicates that neither ion‐pairs nor COOH‐groups are locked inside of the latex particles.In addition to latex particles water‐soluble electrolytes with a relatively high ion concentration are formed during synthesis. Thereby, the formation of imbedded ion‐pairs is reduced or even prevented.