Waterborne Polyurethane Nanocomposites Research Articles

Strong and Tough Lignin-Containing Waterborne Polyurethane Nanocomposites with Multiple Hydrogen Bonds as Photothermal Power Generation Coatings

Strong and Tough Lignin-Containing Waterborne Polyurethane Nanocomposites with Multiple Hydrogen Bonds as Photothermal Power Generation Coatings

Improving fire safety and mechanical properties of waterborne polyurethane by montmorillonite-passivated black phosphorus

A novel phospho-silicon co-flame retardant material composed of montmorillonite modified black phosphorus nanosheets (MMT-BP) is synthesized using a liquid phase intercalation method. MMT-BP nanosheets are utilized to improve the thermal stability, mechanical properties, and fire safety of waterborne polyurethane (WPU). After passivation, MMT-BP nanosheets exhibit high stability during degradation even when immersed in 25 °C water for three months. Compared to pure WPU, the tensile strength of the 0.4-MMT-BP/WPU composite is increased by 59.6%, and the elongation at break is maintained. The limiting oxygen index of the 0.4-MMT-BP/WPU composite is increased from 21.7% to 27.2%. Furthermore, the peak heat release rate, total heat release, and the peak value of smoke production rate of 0.4-MMT-BP/WPU are significantly reduced by 33.43%, 13.85% and 32.40%, respectively. The superior flame-retardancy observed in the WPU nanocomposites containing 0.4 wt% MMT-BP is attributed to the formation of an Si-O-P bond between BP and MMT during passivation and the enhanced catalytic carbonization of BP in the condensed phase. In this paper, an effective passivating method of black phosphorus is proposed and a highly efficient flame retardant based on black phosphorus is obtained.

Bis(2-hydroxyethyl) Terephthalate-Modified Ti3C2Tx/Graphene Nanohybrids as Three-Dimensional Functional Chain Extenders for Polyurethane Composite Films with Strain-Sensing and Conductive Properties.

Incorporation of functional nanofillers can unlock the potential of polymers as advanced materials. Herein, single-layered and three-dimensional reduced graphene oxide (rGO)/Ti3C2Tx (B-rGO@Ti3C2Tx) nanohybrids were constructed using bis(2-hydroxyethyl) terephthalate (BHET) as a coupling agent between rGO and Ti3C2Tx through covalent and hydrogen bonds. It is found that BHET can not only resist the weak oxidization of Ti3C2Tx to some degree but also prevent the self-stacking of Ti3C2Tx and rGO sheets. Then, B-rGO@Ti3C2Tx was used as a functional nanofiller and three-dimensional chain extender for preparing the waterborne polyurethane (WPU) nanocomposite through in situ polymerization. Compared with WPU nanocomposites with an equivalent amount of Ti3C2Tx/rGO@Ti3C2Tx, although containing an equivalent amount of BHET, WPU/B-rGO@Ti3C2Tx nanocomposites show significantly improved performance. For example, 5.66 wt % of B-rGO@Ti3C2Tx endows WPU with a high tensile strength of 36.0 MPa (improved by 380%), thermal conductivity of 0.697 W·m-1·K-1, electrical conductivity of 1.69 × 10-2 S/m (enhanced by 39 times), good strain-sensing behavior, electromagnetic interference (EMI)-shielding performance of 49.5 dB in the X-band, and excellent thermal stability. Therefore, the construction of rGO@Ti3C2Tx nanohybrids with the aid of chain extenders may unlock new possibilities of polyurethane as smart materials.

Mechanically robust and self‐healing waterborne polyurethane nanocomposites based on inorganic organic hybrid materials and reversible covalent interaction

AbstractEndowing waterborne polyurethane (WPU) materials with mechanically reinforced and self‐healing property is a pressing issue for expanding practical applications. In this article, we proposed a simple method to give WPU with self‐healing properties while improving the mechanical properties. First, furfuryl‐modified silica nanoparticles (furan@SiO2) with high functionality and excellent dispersibility were prepared by the sol–gel method. Furan@SiO2 was then introduced into the side‐hanging maleimide WPU to form a thermally reversible inorganic–organic network (WMSPUS‐x) based on the Diels‐Alder reaction. The morphologies and properties of furan@SiO2 and WMSPUS‐x emulsions were analyzed by TEM and DLS, demonstrating the excellent dispersion of furan@SiO2 and the storage stability of emulsions. The cross‐linking density of the nanocomposites was varied by the furan@SiO2 contents, and the effects of cross‐linking density on mechanical and self‐healing properties were systematically investigated. In addition, the thermal stability of WMSPUS‐x nanocomposites was significantly improved shown by TGA results. Finally, qualitative and quantitative studies of the self‐healing process were carried out to verify that WMSPUS‐x nanocomposites possess great self‐healing capacity. The outcomes indicate that WMSPUS‐x nanocomposites have great potential for application as a smart material.

Nanocomposites Based on Waterborne Polyurethane Matrix and Fe3O4 Nanoparticles: Synthesis and Characterization

Herein, the feasibility of producing waterborne polyurethane nanocomposites containing magnetic nanoparticles (MNPs) by casting method, to obtain films with potential magnetic properties, is shown. The characterization of the resulting nanocomposites is carried out using infrared spectroscopy, thermal analysis, colorimetry, tensile tests, microscopy and magnetic tests. The films become opaque and dark colored when MNP is incorporated. The mechanical behavior of the nanocomposites is that of tough plastics, with Young's modulus in the range of 106–143 MPa, increasing with the MNP concentration. Aggregation of the MNP takes place at concentrations above 1.5 wt%, as observed in scanning electron microscopy (SEM) images of the fracture surfaces. Magnetization saturation increases with the concentration of MNP. A small coercivity indicates the presence of a fraction of blocked particles whose size exceeds the critical size for superparamagnetism at the temperature of the measurements.

Waterborne polyurethane nanocomposite incorporated with phytic acid intercalated layered double hydroxides: A highly stable aqueous dispersion with desired corrosion protection capability

AbstractIn this research, waterborne polyurethane (WPU) nanocomposites incorporated with MgAl‐NO3LDH layered double hydroxide (LDH) and phytic acid intercalated LDH (PA‐LDH) nanostructures were prepared as novel environmental‐friendly corrosion protective coatings. Fourier‐transform infrared spectroscopy, X‐ray diffraction (XRD), thermogravimetric analysis, field emission scanning electron microscope (SEM), and high‐resolution transmission electron microscopy analysis confirmed the prosperous preparation of LDHs nanosheets. Moreover, structural, thermal, thermo‐mechanical, and morphological investigations of prepared WPU/LDHs films were also evaluated. The SEM images exhibited that the intercalation of LDH nanosheets with PA could drastically overcome the agglomeration problem of unmodified LDH within the polyurethane matrix. Based on XRD results, WPU/LDHs films showed a lower micro‐phase separation degree and crystallinity compared to pure WPU film. According to wettability analysis, WPU/PA‐LDH film demonstrated the highest hydrophobicity among samples due to its lowest phase‐separation degree, which causes the castor oil and poly(tetramethylene ether) glycol segments to migrate toward the surface of film from the bulk. Furthermore, the potentiodynamic polarization scanning and electrochemical impedance spectroscopy analysis revealed that the WPU/PA‐LDH sample containing 1.0 wt% of PA‐LDH has a superlative anti‐corrosion performance for SS 304 steel with an inhibition efficiency of 99.9%. This superior anti‐corrosive property benefited from the barrier property and chloride absorption capability of well‐dispersed PA‐LDH nanosheets, deposition of PA on the steel substrate, and improved hydrophobicity of the WPU/PA‐LDH coating.

Two-dimensional nanosheets functionalized water-borne polyurethane nanocomposites with improved mechanical and anti-corrosion properties

Waterborne polyurethanes (WPU) have been widely applied in adhesive, leather, paints, leathers, textiles, and coatings. Herein, the reinforcement of 2 D nanosheets, graphene (Gr), graphene oxide (GO) and hexagonal boron nitride (h-BN) on the water resistance, mechanical and anti-corrosion properties of WPU was studied via in situ polymerization method with the loading amount of 0.25 wt%. Fourier Transform infrared spectroscopy analysis revealed no obvious changes in the internal structure of WPU incorporated with these 2 D nanosheets. The scanning electron microscope demonstrates a relatively homogeneous dispersion of h-BN in the WPU matrix. It is clear from the results that the resistance to water, mechanical and anti-corrosion properties of WPU were prominently improved by the incorporation of these nanosheets, especially h-BN, which was ascribed to its homogenous dispersion in WPU matrix and interface adhesion between polymer and filler. In the presence of 0.25 wt% h-BN, the water-absorption rate of WPU decreased from 37.3% to 15.7%, and the tensile strength improved from 4.16 MPa to 19.56 MPa. In conclusion, h-BN might be considered as an ideal nano-filler for WPU as compared to Gr and GO.

Preparation and Properties of Graphene Oxide-Modified Anti-UV Waterborne Polyurethane Nanocomposites

In this present study, graphene oxide (GO) was used as a secondary chain extender and a functional modification assistant to fabricate a three-dimensional nanocomposite (GO-WPU) with waterborne polyurethane (WPU) through the prepolymer dispersion. The tensile strength and elastic modulus of GO-WPU with 0.2[Formula: see text]wt.% GO content, compared with those of pure WPU, increase by 170.38% and 50.9%, respectively. Even with a small amount of GO content added, the ultraviolet absorption rate significantly increased, whereas the ultraviolet transmittance decreased significantly. Other properties such as thermal stability and so on were also much enhanced. These results suggested that the functional nanocomposite GO-WPU prepared through the prepolymer dispersion will be an effective fabrication approach and have a wider scope of applications in functional coating materials and film materials.

Preparation of novel hydrophobic magnetic Fe3O4/waterborne polyurethane nanocomposites

ABSTRACTMagnetic Fe3O4/waterborne polyurethane nanocomposites were synthesized based on waterborne polyurethane (WPU) and amino‐functionalized Fe3O4 by in situ polymerization. The Fe3O4 nanoparticle was found to be uniformly distributed in Fe3O4/WPU nanocomposites with linear or crosslinked structure. In addition, the formation mechanism and magnetic conduction mechanism of stable inorganic–organic nanocomposites were discussed. The experimental results showed that the thermal stability, magnetic, and mechanical properties of magnetic Fe3O4/waterborne polyurethane nanocomposites were improved by amino functionalized Fe3O4. Furthermore, the defoaming property of the emulsion and the hydrophobic property of magnetic Fe3O4/waterborne polyurethane nanocomposites were improved by the 1‐hexadecanol‐terminated prepolymer. What more, polycaprolactone (PCL)‐based Fe3O4/WPU nanocomposites have excellent mechanical properties (The tensile strength is over 30 MPa, the elongation rate is above 300%.) and magnetic properties. Magnetic Fe3O4/waterborne polyurethane nanocomposites will be used in the field of hydrophobic and microwave absorbent materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48546.

Synthetic talc as catalyst and filler for waterborne polyurethane-based nanocomposite synthesis

In this work, synthetic talc was used as catalyst and filler aiming to obtain waterborne polyurethane (WPU) nanocomposites by in situ polymerization. Filler was used both in gel and in powder forms in order to compare its effects into the WPU matrix. The use of synthetic talc as filler is interesting due to the possibility of hydrogen bond formation between WPU chains/Si–O–Si and OH groups in synthetic talc edges promoting changes in physical, mechanical and thermal properties. Moreover, WPUs are environmentally friendly polymers replacing organic solvents by water as dispersion medium reducing pollutant emission in the atmosphere. Material structure analyzed by FTIR evidenced that it is possible to synthesize WPU using synthetic talc as catalyst and proved hydrogen bonding formation between synthetic talcs and WPU matrix. Synthetic talcs were well dispersed even with higher filler content, as supported by XRD, TEM, FESEM and AFM analyses. Thermal and mechanical performance was improved with synthetic talc fillers’ addition in order to obtain WPU nanocomposites. Also, Tg of WPU nanocomposites was affected by fillers’ addition as presented by DSC corroborating synthetic talc good dispersion as evidenced by XRD and TEM analyses. Synthetic talcs used as catalyst/filler resulted in nanocomposites with superior thermal and mechanical properties being a new path to utilize synthetic talcs to obtain multifunctional materials.

Waterborne polyurethane/graphene oxide-silica nanocomposites with improved mechanical and thermal properties for leather coatings using screen printing

Waterborne polyurethane (WPU) has been broadly used as adhesive and coating materials in many applications. In this work, the graphene oxide-silica (GOSI) nanocomposites, used as nanofillers in the WPU matrix, were produced by functionalizing graphene oxide with epoxy groups and nanosilica with amine groups using silane terminated coupling agents. The nanocomposite surface structures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The polymer nanocomposite films show the excellent improvement in the mechanical and thermal properties. In the fractured surface study of the composite films by SEM, it was observed that the agglomeration of GO appears while the GOSI is uniformly distributed in the WPU matrix. Furthermore, the WPU/GOSI have regained the maximum tensile strength properties after two weeks of hydrolysis. The GOSI nanocomposites have enhanced interfacial crosslinking with the WPU matrix which is the prime reason for such development in the mechanical properties. The screen printing method was illustrated to cast the thin and transparent layer WPU nanocomposites on the leather surfaces. The WPU/GOSI coatings exhibit outstanding tear resistance, surface adhesiveness, and abrasion resistance properties. This approach of using GOSI composites as nanofiller in the polymer matrix may pave a novel path for surface coating strategies.

Synthesis, thermal and anticorrosion performance of WPU nanocomposites with low carbon-black content by adding amine-modified multiwall carbon nanotube

A novel waterborne polyurethane (WPU) nanocomposite modified by composite fillers consists of amine-modified multiwall carbon nanotube (NH2-MCNT) and carbon black (CB) has been successfully prepared in this study. IR spectra of the nanocomposites indicated that there were interfacial interactions between the hard segments of PU chains and the filler particles. Thermal properties showed that added composite fillers raised the thermal stability of nanocomposites and glass transition temperature of hard segments (Tg-H), which was probably due to the uniformly dispersed filler particles, increased crosslink density of composites and the strong interfacial interactions between the fillers and WPU matrix evidenced by SEM and TEM microphotographs. Furthermore, the other properties of nanocomposite coatings were evaluated by contact angle measuring system and potentiodynamic polarization measurements. The results indicated that the fillers strengthened the hydrophobicity of the nanocomposites coatings and enhanced the resistance to corrosion.

Preparation of β-cyclodextrin reinforced waterborne polyurethane nanocomposites with excellent mechanical and self-healing property

Cyclodextrin is an eco-friendly material with extensive application range. In this work, polyethylene glycol (PEG) modified β-cyclodextrin (CD) was added to a self-healing waterborne polyurethane (SHWPU) through a simple solution blending method. The morphologies, chemical structures, emulsion stability, thermal behavior, mechanical and self-healing properties of the SHWPU/CD nanocomposites were investigated. The results indicated that CDs were well dispersed in the SHWPU matrix and the blended emulsions were stable. The thermal stability of the SHWPU was improved by the addition of CD. When the mass fraction of CD was lower than 5%, the mechanical and self-healing property of the nanocomposites were obviously improved, which indicates the CD modified SHWPU can find potential applications in durable coatings and adhesives in areas, such as textile, wood, aerospace and infrastructure.

Polydopamine functional reduced graphene oxide for enhanced mechanical and electrical properties of waterborne polyurethane nanocomposites

Waterborne polyurethane/polydopamine (PDA) functional reduced graphene oxide (WPU/PDRGO) nanocomposites were prepared by in situ emulsification method. The presence of a PDA layer and the partial reduction of GO by PDA were confirmed by FTIR, XRD, Raman spectra, and TGA. It was found that the interfacial PDA layers facilitated the dispersion of the PDRGO sheets in the WPU matrix and enhanced mechanical properties of the WPU matrix. The resulting WPU/PDRGO nanocomposite coatings show excellent electrical conductivity (9.9 × 10−6–1.1 × 10−4 S cm−1) corresponding to a PDRGO content of 1–16 wt%. The obtained waterborne polyurethane/graphene nanocomposite dispersions are promising for anticorrosion, antistatic, conductive, and electromagnetic interference shielding coatings.

Synthesis of aminosilane crosslinked cationomeric waterborne polyurethane nanocomposites and its physicochemical properties

A series of cottonseed oil based waterborne polyurethane–silica (CSOWPU–Si) hybrid materials were prepared via the chemically interaction between NCO groups of polyurethane prepolymer and the surface of 3-aminopropyl trimethoxysilane (APTMS). The biobased triglyceride oils were first epoxidized cottonseed oil followed by oxirane ring-opened with varying polyhydroxy (OH) fatty acid numbers. The attached modified APTMS thus performed the dual roles not only chain extender filler but including reinforcing agent in the resulting hybrid coatings. Fourier transform infrared spectra expose the crosslinking interaction between polyurethane and the appearance of silica nanoparticles in the polymer matrix. The 29Si solid-state NMR spectra sign the formation and the behavior of siloxane linkage in the CSOWPU–Si nanocomposites films. Dynamic mechanical analysis (DMA) studies show that the appearance of silica nanoparticles provides rigidity to CSOWPU–Si film, thereby enhancing the storage modulus. The effect of crosslinking density and thermophysical and mechanical properties of the polyurethane and the resulting hybrid materials films was evaluated by the differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and measurement of the mechanical properties. This work renders a new effective and promising route of utilizing biorenewable for the development of CSOWPU–Si hybrid materials with high performance coating applications.

Effect of octa(aminopropyl) polyhedral oligomeric silsesquioxane (OapPOSS) functionalized graphene oxide on the mechanical, thermal, and hydrophobic properties of waterborne polyurethane composites

ABSTRACTA novel graphene nanomaterial functionalized by octa(aminopropyl) polyhedral oligomeric silsesquioxane (OapPOSS) was synthesized and then confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM EDX), atomic force microscopy, and X‐ray diffraction. The obtained functionalized graphene (OapPOSS‐GO) was used to reinforce waterborne polyurethane (WPU) to obtain OapPOSS‐GO/WPU nanocomposites by in situ polymerization. The thermal, mechanical, and hydrophobic properties of nanocomposites as well as the dispersion behavior of OapPOSS‐GO in the polymer were investigated by TGA, a tensile testing machine, water contact angle tests, and field emission SEM, respectively. Compared with GO/WPU and OapPOSS/WPU composites, the strong interfacial interaction between OapPOSS‐GO and the WPU matrix facilitates a much better dispersion and load transfer from the WPU matrix to the OapPOSS‐GO. It was found that the tensile strength of the OapPOSS‐GO/WPU composite film with 0.20 wt % OapPOSS‐GO exhibited a 2.5‐fold increase in tensile strength, compared with neat WPU. Better thermal stability and hydrophobicity of nanocomposites were also achieved by the addition of OapPOSS‐GO. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44440.

Waterborne polyurethane nanocomposites based on vegetable oil and microfibrillated cellulose

ABSTRACTThis work analyzes the differences in the final properties of two waterborne polyurethanes (WBPU) prepared with two macrodiols of different chemical structure, but similar molecular weight, as well as the variations caused by incorporating low percentages of microfibrillated cellulose nanocrystals. One of the polyurethanes was based on a synthetic but biodegradable precursor (polycaprolactone diol, PCL) and a second one based on a bio‐based macrodiol derived from castor oil (CO1). The bio‐based material presented higher mechanical properties at room temperature than the synthetic one, with the Young's modulus (MPa) ranging from 2.23 ± 0.09 to 84.88 ± 0.96 for the PCL and bio‐based WBPUs, respectively. Additionally, the PCL‐based WBPU showed to be more sensitive to the incorporation of cellulose than the bio‐based WBPU, and it also suffered changes during time due to delayed crystallization. The behavior of the two systems were compared and related to the different structure of the macrodiols that led to different interfacial interactions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44207.

Bio-based waterborne polyurethane/carbon dot nanocomposite as a surface coating material

Abstract Waterborne surface coating materials with low volatile organic compounds (VOCs) are environmentally friendly and hence the most desired materials for the modern society. The present study reports in situ fabricated thermosetting hyperbranched waterborne polyurethane (WPU)/carbon dot (CD) nanocomposites as surface coating materials. CD was used as a nanoreinforcing agent (at 0.25, 0.5 and 1.0 weight percentages) in the nanocomposites. The structures of the waterborne polyurethane and its fabricated thermosetting nanocomposites were analyzed by using different spectroscopic and analytical tools like Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, UV–visible spectroscopy and X-ray diffractometry. The mechanical properties of the pristine thermosetting WPU were significantly improved after incorporation of CD (tensile strength from 4.5 to 8.5 MPa, elongation at break value from 96 to 136%, scratch hardness from 3 to 9 kg, impact strength from 70 to 100 cm). The thermal stability of WPU also enhanced from 250 to 280 °C after incorporation of CD in the matrix. Interestingly, the fabricated nanocomposites demonstrated an excitation wavelength and concentration dependent photoluminance behavior as well as exhibited good transparency. Thus, the fabricated WPU nanocomposites show great potential as low VOC containing environment friendly transparent surface coating material.

Synthesis and characterization of polyhedral oligomeric silsesquioxane-based waterborne polyurethane nanocomposites

A series of aqueous polyurethane nanocomposites were prepared using various amounts (0.3-4.6 wt%) of a diol functionalized polyhedral oligomeric silsesquioxane (POSS) by the prepolymer mixing method. N,N-bis(2-hydroxy ethyl-2-amino ethane sulfonic acid sodium salt (BES sodium salt) was used as the anionic internal emulsifier and ionic center. The molecular structure of the samples was characterized by ATR-FTIR spectroscopy. We investigated the effect of the POSS contents on the properties of the specimens by particle size and viscosity measurements, X-ray diffractometry, mechanical behavior assessment, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis and morphological studies. The results showed that with increasing the POSS contents, particle size, viscosity, tensile strength, modulus, Tg, and thermal stability of the synthesized samples were improved. Also, SEM and TEM images indicated that a homogeneous morphology was obtained in the 1.2 wt% POSS-based sample. AFM results showed that the surface roughness increased as the POSS amounts increased.

Hybrids of silver nanowires and silica nanoparticles as morphology controlled conductive filler applied in flexible conductive nanocomposites

Flexible conductive polymer nanocomposites based on silver nanowires (AgNWs) have been widely studied to develop the next generation of flexible electronics. However, AgNWs tend to aggregate in polymer matrix that usually results in high percolation threshold. In this study, nonconductive silica nanoparticles (nano-SiO2) were successfully co-assembled on AgNWs to form AgNWs/nano-SiO2 hybrids and waterborne polyurethane (WPU) conductive nanocomposites filled with the hybrids were prepared. The results show that the resistivity of WPU nanocomposites filled with AgNWs/nano-SiO2 hybrids decreased about 5000 times and the percolation threshold decreased from 10.6vol% to 3.6vol% due to AgNWs distribute more uniformly in WPU with the help of nano-SiO2. The further study to mechanism of interactions between AgNWs and nano-SiO2 suggest that the promotion of dispersion is attributed to hydrogen bonding and van der Waals force. The WPU nanocomposites embedded with AgNWs/nano-SiO2 hybrids present excellent mechanical adhesiveness, flexibility and thermal stability.