Synthesis and Characterization of Nonionic Waterborne Polyurethane and Application to Wool Fabric Finishing

A nonionic waterborne polyurethane(WPU) was synthesized by the self-emulsification method using polyether diol(N220),isophorone diisocyanate(IPDI),trimethylolpropane poly(ethylene glycol monomethyl ether)(N120),1,4-butanediol(BDO) and trimethylolpropane(TMP) as the main materials.The effects of the NCO/OH ratio on the emulsion and film properties of NWPU were explored.The experimental results show that the NWPU prepared at an NCO/OH ratio of 1.1 has good emulsion stability and easy film formation,and the resultant film was elastic,soft,and transparent.The sample was used for wool finishing and the application performance was evaluated.When the NWPU dosage reached 40 g·L^(-1),the fabric area felt shrinkage rate reduced from 8.97% to 4.75%,the pilling rating raised from grade 2-3 to grade 4,and the whiteness value only decreased by 3.87%.

Preparation and Tribological Properties of Onion-like Carbon/Waterborne Polyurethane Coatings

Rice husk powder was used as a carbon source in a high-temperature carbonization reaction for the production of rice husk ash(RHA).Under the catalysis of ferric nitrate,onion-like carbon(OLC)nanomaterial with a particle size of approximately 200 nm was successfully prepared and incorporated into waterborne polyurethane(WPU).The tribological properties of the coatings were determined using a controlled-atmosphere tribometer(WMT-2E)under dry-friction conditions.Following the friction test,the friction mechanism was investigated by characterizing the abrasive spot surfaces of the test samples using 3D laser microscopy and scanning electron microscopy/energy dispersive spectrometer.The final results demonstrated that the thermal stability of WPU composite coatings containing various concentrations of OLC nanoparticles was significantly enhanced,binding forces between coatings and steel sheets increased,and hardness improved compared to pure WPU coatings.Tribological tests revealed a notable enhancement in the anti-wear properties of WPU coatings due to the presence of OLC particles.Specifically,the wear rate of the 1.5%OLC/WPU coating was reduced by 45.3%.The coating’s anti-wear mechanism was attributed to the improvement in the mechanical properties of WPU due to OLC,as well as OLC’s participation in the formation of a transfer film under induced friction,which protected the matrix.

Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

Preparation of waterborne polyurethane/β-cyclodextrin composite nanosponge by ion condensation method and its application in removing of dyes from wastewater

Currently,polymer nanosponges have received extensive attention.However,developing new synthetic techniques for novel nanosponges remains a challenge.Furthermore,to date,composite nanosponge adsorbents based on waterborne polyurethane(WPU)andβ-cyclodextrin(β-CD)have not been reported.Herein,a novel green method,ion condensation method,was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater.Based on the principle of charge repulsion between nanoparticles to maintain emulsion stability,waterborne polyurethane/β-cyclodextrin composite nanosponges(WPU-x,y)were prepared by coagulating the emulsions synthesized from 2,2-dimethylolpropionic acid,polypropylene glycol and hexamethylene diisocyanate as raw materials in a mixture of hydrochloric acid and anhydrous ethanol.The structure and appearance of WPU-x,y were characterized by attenuated total reflectance Fourier transform infrared spectroscopy,thermal gravimetric analyzer,scanning electron microscope and mercury intrusion porosimetry.The adsorption capacity of WPU-x,y was tested by parameters such as cross-linking degree,β-CD dosage,contact time,initial dye concentration and p H value.The study found that WPU-4,4.62 had the best adsorption effect on methylene blue(MB),the maximum removal rate was 93.42%,and the maximum adsorption capacity was 136.03 mg·g^(-1).Moreover,the Sips isotherm and pseudo-second-order-model were suitable for MB adsorption.Therefore,this study provides some perspectives for the fabrication of nanosponge adsorbents.

Preparation and Characterization of Cellulose Nanofibril-Waterborne Polyurethane Composite Films

To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.

High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study,acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization.The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly(acrylic acid)(WPU-PAA)dispersion and the films were systematically investigated.The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid,leading to enhancement of the mechanical properties and water resistance of WPU-PAA films.Notably,with the increase in content of acrylic acid,the tensile strength,Young’s modulus,and toughness of the WPU-PAA-110 film increased by 3 times,and 8 times,and 2.4 times compared with WPU-PAA-80,respectively.The WPU-PAA-100 film showed the best water resistance,and the water absorption rate at 96 h was only 3.27%.This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Preparation and Characterization of Two-component Waterborne Polyurethane Comprised of Water-soluble Acrylic Resin and HDI Biuret

A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.

Preparation and characterization of a mixing soft-segment waterborne polyurethane polymer electrolyte

The mixing soft-segment WPU （waterborne polyurethane） polymer electrolytes were synthesized by using PEO （poly（ethylene oxide）） and PDMS （polydimethylsiloxane） as the soft segments. These polymer electrolytes exhibit good thermal and electrochemical stabilit）＇. The conductivity of the gel polymer electrolyte is 2.52 × 10^-3 S/cm at 25 ℃ with the LiTFSI/（DMC ＋ EC） content of 130%.

Preparation and Surface Properties of Silicon-Containing Waterborne Polyurethane Functionalized with Fluorine-Containing Acrylate and Micro-Nano Silica

In order to prepare hydrophobic waterborne polyurethane coatings with better performances, the silicon-containing waterborne polyurethane（SiWPU） with functional chain extender hydroxyethyl acrylate（HEA） was prepared first, and then a series of silicon＆fluorine-containing polyurethane/acrylate（FSiPUA） emulsions were obtained with flourine containing acrylic monomer by seed emulsion polymerization, introducing micro-nano SiO2 into FSiPUA emulsion to make the final hybrid emulsion. The properties of Si WPU, FSiPUA and SiO2/FSiPUA were investigated by fourier transform infrared spectra（FTIR）, transmission electron microscope（TEM）, Scanning Electron Microscope（SEM） and some other analytical methods. The results revealed that FSiPUA emulsion particles possessed composite core-shell structure and FSiPUA films with suitable ratio performed better than Si WPU films in hardness, water resistance and solvent resistance. The SiO2/FSiPUA films with micro-nano dual roughness structure showed a water contact angle of 136° with good resistance to acid and alkali.

Synthesis and characterization of mixing soft-segmented waterborne polyurethane polymer electrolyte with room temperature ionic liquid

Composite polymer electrolytes based on mixing soft-segment waterborne polyurethane （WPU） and 1-butyl-3-methylimidazolium bis[（trifluoromethyl）sulfonyl]imide （BMImTFSI） have been prepared and characterized. The addition of BMImTFSI results in an increase of the ionic conductivity. At high BMImTFSI concentration （BMImTFSI/WPU = 3 in weight ratio）, the ionic conductivity reaches 4.27 × 10^-3 S/cm at 30 ℃. These composite polymer electrolytes exhibit good thermal and electrochemical stability, which are high enough to be applied in lithium batteries.

Preparation and Characterization of Waterborne Polyurethane/Cellulose Nanocrystal Composite Membrane from Recycling Waste Paper

Cellulose plays a key role in abundant organic natural materials meeting the increasing demand for green and biocompatible products.The highly crystalline nanoscale component of cellulose nanocrystals has recently attracted great attention due to the versatile performance as filler or matrix in producing functional materials.In this work,we prepared the waterborne polyurethane via a prepolymer process,and obtained cellulose and cellulose nanocrystals from waste paper via a facile acid hydrolysis process.After that,the cellulose nanocrystals were assembled into film and mixed with polyurethane to prepare flexible polyurethane/cellulose nanocrystals composite membrane with different soaking time.The correlation between the bulk structure and applied properties including thermal resistance and mechanical property was investigated by using Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and folding test.The structure analysis indicates that cellulose nanocrystals prepared from used paper have a quality similar to that of commercial cellulose.Meanwhile,the cellulose nanocrystals have been mixed with polyurethane uniformly.Polyurethane can significantly benefit to the thermal resistance and mechanical property of the cellulose nanocrystals film.The polyurethane/cellulose nanocrystals composite membrane present good flexibility and may hold a significantly potential application as visual and flexible material.

Plant Oil-Based Waterborne Polyurethanes: A Brief Review

The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.

Synthesis of Waterborne Polyurethane Modified by Nano-SiO_2 Silicone and Properties of the WPU Coated RDX

A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.

Synthesis of Castor Oil-based Cationic Waterborne Polyurethane Emulsion and Its Application

Castor oil-based cationic waterborne polyurethane(CWPU)was synthesized by pre-polymer process using castor oil(CO),poly(adipic acid-1,4-succinate diol)(PBA),isophorone diisocyanate(IPDI),and N-methyldiethanolamine(MDEA).The influences of the content of CO and MDEA on comprehensive performance and finished fabric properties of cationic waterborne polyurethane was investigated,especially the antibacterial properties of finished fabric.The CWPU latex particle size and its distribution decrease as the content of CO increased from 0wt%to 16.8wt%,and increases afterwards.The CWPU films show much higher thermal stability than cationic waterborne polyurethane without CO.The surface of fabrics was characterized by scanning electron microscope(SEM).The finished fabric surface is much smoother.In addition,the finished fabric with CWPU emulsion has better antibacterial property against E.coli and S.aureus.When MDEA content is 8%,the antibacterial rates of the two kinds of bacteria are 77.3%and 82.2%,respectively.

Enhanced Water Resistance Performance of Castor Oil—Based Waterborne Polyurethane Modified by Methoxysilane Coupling Agents via Thiol-Ene Photo Click Reaction

Nowadays,waterborne polyurethanes(WPUs)prepared from renewable resources has attracted more and more attention.However,due to its structure,the prepared films easily swells in water and greatly affects the application range of WPUs.Therefore,solving the problem of water resistance is a way to improve the application range of WPUs.In this study,a series of WPU dispersions were prepared using castor oil as the bio-based polyol.Besides,the thiol-ene photo click reaction was carried out on the WPU films for silane modification.The effect of the silane modification on the chemical structures of the WPU dispersions and the properties of the WPU films was investigated and discussed.The results revealed that the WPU dispersions had a smaller particle size and potential,showing excellent stability.In addition,the modified WPU films showed highly water resistance which 72 h water absorption could be reduced to 1.94%and the contact angle was up to 99.34?.Moreover,the modified WPU films also exhibited excellent solvent resistance(in acid and salt solution)and thermal stability.This study can provide a new way to improve the water-resistance,hydrophobicity,and thermal stability of bio-based waterborne polyurethane for potential application in painting,adhesives and inks.

Synthesis and Characterizations of 1,4-butanediol( BDO )-Regulated Poly( ε-caprolactone)(PCL) Waterborne Polyurethane with Controlled Biodegradability for Medical Applications

Waterborne polyurethane （ WBPU ） with controlled biodegradability and biocompatibility was synthesized by using poly （ε-caprolactone） （ PCL ） as the polyglycol, isophorone diisocyanate （IPDI） as the isocyanate, 2 acid （DMPA） as the chain extender and 1, 4-butanediol （BDO） as the hard-segment regulating agent. We found that BDO content significantly influenced mechanical properties, degradable performances and cyto-biocompatibility of PCL-WBPUs. Increasing the BDO content in PCL-WBPU enhanced its tensile strength and decreases strain. Enzymolysis and hydrolysis properties were also regulated by BDO content, but with different meechanisms. Cyto- biocompatibility was evaluated with ATDC5 cells. The results show that the biodegradability of PCL-WBPU is significantly determined by BDO content, which exerts a serious influence on its polymer structure, leading to resultant degradable properties.

Robust Waterborne Polyurethane/Wool Keratin/Silk Sericin Freeze-Drying Composite Membrane for Heavy Metal Ions Adsorption

Wool keratin(WK)and silk sericin(SS)have the ability to interact with metal ions.In order to take advantage of this potential,a novel environmentally friendly waterborne polyurethane(WPU)/WK/SS membrane named as WPU&WK&SS membrane with crosslinked structure was constructed by freeze-drying via self-assembly style.Surface morphology and chemical structure characterization were investigated by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR).In addition,the adsorption experiments of Cu2+and Cr6+were performed to evaluate the adsorption of WPU&WK&SS membrane,including adsorption kinetics,adsorption isotherm models and various factors affecting adsorption.Further investigation indicates that the maximum adsorption capacity of Cu2+and Cr6+can reach 54.21 mg·g-1and 85.21 mg·g-1,respectively,which are higher than most of the reported adsorbents.Through adsorption kinetics and thermodynamic analysis,it is find that the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model are more suitable for the static adsorption of Cu2+and Cr6+by WPU&WK&SS membrane.

Structure and Mechanical Properties of Waterborne Polyurethane-based Composites Filled with Self-assembled Supramolecular Nanoplatelets

New composites of waterborne polyurethane （WPU） as a matrix were prepared by incorporating rigid supramolecular nanoplatelets （SNs） as filler, which were self-assembled by the selective inclusion of β-cyclodextrin （β-CD） onto poly（propylene oxide） （PPO） segment in the poly（ethylene oxide）- block-PPO-block-poly（ethylene oxide） （PEO-b-PPO-b-PEO）. It is worth noting that, when the loading level of SN is lower than 3wt%, the SNs with moderate PEO length result in the simultaneous increase in strength, elongation and Young＇s modulus in contrast with neat WPU. If there is no stretching free PEO chain, both strength and elongation decrease in spite of an increase in Young＇s modulus. However, too long PEO chains result in the decrease of mechanical performances while the relatively higher loading-level of SNs also inhibits the enhancement of strength and elongation.

Pyrolysis Study of Waterborne Polyurethane

The thermal degradation of synthetic waterborne polyurethane（PU） based on toluenediisocyanate（TDI） was investigated by pyrolysis-gas chromatography/mass spectrometry（Py-GC/MS） and thermogravimetry（TG）.The degradation profiles of cast films obtained from dispersions were evaluated.More than 20 characteristic volatile pyrolyzates reflecting the structure and pyrolysis mechanisms of the polymer have been identified by on-line MS.In helium atmosphere,the synthesized products of polyurethane were pyrolyzed at 350,450,550,650 and 750 ℃ respectively,and the thermal decomposition products were analyzed on line using GC/MS.The product analysis reveals that the pyrolyzates distribution of the polyurethane depends strongly on the pyrolysis temperature.Based on the Py-GC/MS data,the thermal degradation mechanism of the polyurethane is discussed.

Bio-Inspired Gelatin-Based Adhesive Modified with Waterborne Polyurethane on Click Chemistry

As a non-toxic,highly reactive biomass material,gelatin is wildly used as the component of biomass-based adhesive.However,like most aqueous adhesives,gelatin-based adhesives suffer from long solidifying time or high solidifying temperature due to the low volatility of water,which highly limits the application potential of gelatinbased adhesives.Inspired by the fast adhesion of marine organisms through the formation of chemical crosslinks,herein,a kind of low temperature curable eco-friendly gelatin-based adhesive with good adhesive properties and fast curing at low temperature is developed by introducing clicking chemical Diels-Alder(DA)reaction between blocked waterborne polyurethane(MWPU)and gelatin.The furfuryl glycidyl ether(FGE)and 4-Maleimidophenol(4-HPM)for the DA reaction are grafted on gelatin,and the end-capping of MWPU,respectively.With the addition of MWPU and FGE,the cross-linking degree of gelatin increased,and the adhesion properties of the adhesive were improved.The shear strength and T-peel strength of the modified adhesive reached 0.95 MPa and 1.42 N/mm,respectively,after the curing time of 8 min at 40℃,which can meet the application requirements as adhesive for bio-medical use.