Pure Waterborne Polyurethane Research Articles

Degradable cellulose acetate-based waterborne polyurethane sand-fixing agents for sand control in desert regions

In hot and arid desert regions, degradable chemical sand-fixing agents are efficient in dealing with problems caused by wind-blown sand movement without damaging the environment. This study aimed to develop a set of biodegradable sand-stabilizing substances, cellulose acetate (CA)-based waterborne polyurethane (WPU), utilizing CA as a partial hydroxyl provision through an acetone-based technique. The findings demonstrate that all the CA/WPU sand-fixing agents had unique, evenly spherical particles and were fully capable of degradation. The CA/WPU-2 sand-fixing agent contained 20 % polypropylene glycol (PPG) of CA. It showed strong viscosity, thermal stability, and water resistance. Furthermore, seed germination will be hindered by the CA/WPU-2 sand-fixing agent due to its superior sand-fixing capability compared to pure WPU. Consequently, it is suitable for application in arid regions where plant survival is difficult. CA/WPU-6 contained 120%PPG of CA. it showed outstanding O2 permeability and hydrophilicity due to its significant use of cellulose acetate. In addition, it demonstrated higher wind-blown sand resistance compared to popular commercial sand-fixation production. Furthermore, it sustained a consolidation strength lower than the highest penetration capability for herbaceous plant seeds. Therefore, CA/WPU-6 is a suitable option for establishing vegetation in dry situations. The results of this study address the demand for sustainable production and cost reduction, offering significant potential for industrial applications.

Performance and Morphology of Waterborne Polyurethane Asphalt in the Vicinity of Phase Inversion.

Waterborne polyurethane asphalt emulsion (WPUA) is an environmentally friendly bituminous material, whose performance is highly dependent on the phase structure of the continuous phase. In this paper, WPUAs in the vicinity of phase inversion were prepared using waterborne polyurethane (WPU) and asphalt emulsion. The chemical structures, thermal stability, dynamic mechanical properties, phase-separated morphology and mechanical performance of WPUAs were studied. Fourier-transform infrared (FTIR) spectra revealed that there are no -NCO bonds in either the pure WPU or WPUAs. Moreover, the preparation of WPUA is a physical process. The addition of WPU weakens the thermal stability of asphalt emulsion. WPU improves the storage modulus of asphalt emulsion at lower and higher temperatures. The glass transition temperatures of the WPUA films are higher than that of the pure WPU film. When the WPU concentration increases from 30 wt% to 40 wt%, phase inversion occurs; that is, the continuous phase shifts from asphalt to WPU. The WPUA films have lower tensile strength and toughness than the pure WPU film. However, the elongations at break of the WPUA films are higher than that of the pure WPU film. Both the tensile strength and toughness of the WPUA films increase with the WPU concentration. Due to the occurrence of phase inversion, the elongation at break, tensile strength and toughness of the WPUA film containing 30 wt% WPU are increased by 29%, 250% and 369%, respectively, compared to the film with 40 wt% WPU.

The impact of DOPO‐derived phosphoramides containing triazine moieties on the flame retardancy and smoke suppression properties of waterborne polyurethane

AbstractWaterborne polyurethane (WPU), which is a novel and environmentally friendly variety of polyurethane, replaces organic solvents with water. It has been extensively utilized in diverse fields encompassing coatings, textile finishing, building decoration, adhesives, plastic chemistry, and others. However, WPU is inherently flammable and releases a significant amount of smoke production during the combustion process. This research presents an original fire‐resistant Waterborne Polyurethane (WPU) with a newly‐integrated flame‐retardant component comprising a triazine phosphoramidate segment derived from 9,10‐dihydro‐9‐oxo‐10‐phosphaphenanthrene‐10‐oxide (DOPO) within its primary structure. In comparison to pure WPU, the limiting oxygen index (LOI) of flame‐retardant WPU (FRWPU) increased from 19.6% to 29.2%. In UL‐94 testing, the FRWPU film achieved a V‐0 rating with only 6% retarding component. Additionally, in cone calorimetry tests, Total Heat Release (THR), peak Heat Release Rate (pHRR), Total Smoke Production (TSP), Smoke Production Rate (SPR), and peak Carbon Monoxide Production Rate (pCOP) are decreased by 27.7%, 16.2%, 64.6%, 61.3%, and 77.8%, respectively. The greater degree of graphitization observed in the residual carbon substantially impeded heat exchange and the emission of smoke during combustion. Flame‐retardant intermediate segments greatly improved the FRWPUs' ability to suppress smoke and remain flame‐retardant. The creation and formulation of aqueous polyurethanes that are flame‐retardant can benefit greatly from the insights and references offered by this research.

Sustainable waterborne polyurethane/lignin nanoparticles composites: Durability meets degradability

Optimizing the durability and degradability of polymers is essential for prolonging their useful life and minimizing their environmental footprint post-use, contributing to a sustainable world; however, durability in many cases conflicts with degradability. In this context, we developed lignin-based waterborne polyurethane (WPU) composites that bypass this dichotomy. Lignin nanoparticles (LNP), derived from enzymatic hydrolysis lignin (EHL), were synthesized using the anti-solvent method and incorporated into WPU emulsions through solution blending. The introduction of 5 wt% LNP notably improved the tensile strength of WPU composites, increasing it from 21.5 MPa to 29.7 MPa, a surge of up to 38 %. Moreover, 5 wt% of LNP significantly enhanced the durability of WPU by reducing creep strain (under a stress of 1 MPa for 3000 s) from 606 % to 70 % with an 88 % decrease, and by increasing molecular weight retention rate from 11 % to 87 % after 15 days of UV exposure. Concurrently, LNP notably accelerated the alkaline degradability of WPU/LNP composites, with weight loss rate increasing from 38 % to 92 % (a 142 % increase) and molecular weight loss from 17 % to 44 % (a 159 % increase), compared to pure WPU. The strategy employed in this study leverages the inherent properties of LNP to offer a promising approach to enhancing polymer sustainability, presenting an effective solution to the significant end-of-life challenge.

A new strategy to improve the anticorrosion performance of waterborne polyurethane coating on AA7075

In this study, Ce3+ functionalised halloysite nanotubes (HNTs) were prepared, and their impact on the anticorrosion properties of waterborne polyurethane (WPU) coating on 7075 aluminium alloy (AA7075) was investigated. HNTs were grafted by 3-aminopropyltriethoxysilane (APTES) to enhance Ce3+ loading, which was confirmed by X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectrum. The release behaviour of Ce3+ from HNTs was tested by inductively coupled plasma optical emission spectrometry (ICP-OES), and the inhibition effect of Ce3+-loaded HNTs for AA7075 was tested by polarization plots. The anticorrosion property of WPU doped with Ce3+-loaded HNTs was investigated by electrochemical impedance spectroscopy (EIS) and pull-off adhesion test. The results showed that APTES modification improved the Ce3+ loading amount on HNTs, and Ce3+ acts as an effective cathodic inhibitor for AA7075. After soaking for 40 days, the |Z|0.01Hz of Ce-HNTs/WPU was two orders of magnitude higher than that of pure WPU, while wet put-off adhesion was higher than pure WPU.

Synthesis of phytic acid doped trimer aniline/graphene oxide waterborne coatings for cooperatively enhanced corrosion protection in 3.5 % NaCl solution

As an important derivative of graphene, graphene oxide(GO) is widely applied in multiple fields due to the abundant active sites and large specific surface area. In this paper, phytic acid(PA) had been chosen to modify the simple aniline trimer(AT) integrate with GO for acquiring a significant improvement of marine corrosion protection. Moreover, waterborne polyurethane(WPU) was used as a coating substrate to prepare a novel kind of functional coating on metal with nontoxicity. An enhanced electrical performance had been discovered through the combination of PA-AT and GO, which could be attribute to the unique 2-dimensional structure and π-π* interactions between GO and PA-AT. Then, the results of electrochemical measurements performed in 3.5 wt% NaCl solution showed an excellent corrosion protection when the ratio of GO to PA-AT stood at 1:3. Meanwhile, the most significant protective effect was observed with a dosage of 0.8 g of GO/PA-AT compared with the pure WPU. Similarly, the hardness, adhesion and impact resistance, and contact angle of GO/PA-AT coating also obtained a significant improvement based on the performance measurement. As a result, GO/PA-AT composite could provide an efficient protective performance against electrolyte diffusive corrosion in this paper.

A simple surface engineering to develop the potential of carbon nitride nanosheets in high-performance polymer nanocomposites conducted by first-principles calculations

The incompatible interface between carbon nitride (CN) nanosheets and polymer resin is a huge challenge to develop high-performance polymer/CN nanocomposites. Recently, the complicated surface functionalization methods reported severely hinder the commercial production and practical application of polymer/CN nanocomposites. Herein, conducted by the first-principles calculations, a simple surface engineering is put forward to change the surface characteristic of CN nanosheets by rapidly introducing oxygen atoms with a chemical oxidation method. Presented by the first-principles calculations, it is found that the introduction of oxygen atoms can enhance the adsorption energy between oxygen-doping carbon nitride nanosheets (OCN) and waterborne polyurethane (WPU) resin. As a result, a stronger interfacial interaction and better dispersion state are presented in WPU/OCN nanocomposites, thus laying the foundation for the properties enhancement. Further, effective suppression effects for thermal pyrolysis and fire hazards of WPU resin are demonstrated by OCN nanosheets. As presented by cone calorimeter results, the peak values of heat release rate and total heat release in WPU/OCN-2 are decreased to 806 kW/m2 and 43.3 MJ/m2, significantly less than those of pure WPU (1028 kW/m2 and 55.9 MJ/m2). Meanwhile, more char residue, lower signal intensity of pyrolysis gas, and a prolonged time for signal peak also confirm that the addition of 2.0 wt% OCN nanosheets can hinder the thermal degradation behavior of WPU resin. In addition, the introduction of oxygen atoms promotes the formation of hydrogen bond interactions between OCN nanosheets and WPU matrix, thus enhancing interfacial compatibility and overcoming the re-stack problem. As a result, break strength and elongation at break of WPU/OCN-2 are up to 621% and 24.4 MPa, respectively. The combination of first-principles calculations and surface engineering opens a new approach for designing and developing high-performance polymer nanocomposites.

Fabrication of organic/inorganic hybrid waterborne polyurethane coating based on CeNPs @mTi3C2Tx composites for anti-corrosion applications

Ti3C2Tx has been studied as a nano-filler in anti-corrosion coatings, but its poor dispersion, interfacial interaction in coatings and poor long-term anti-corrosion performance limit its application. A series of organic/inorganic hybrid waterborne polyurethane anti-corrosion coatings were designed and prepared based on the barrier effect of MXene and the passivation mechanism of CeNPs, providing a green, environmentally friendly, and long-term efficient organic/inorganic hybrid anti-corrosion method. FT-IR, zeta potential, XPS and EDX analysis showed that the nano ceria was successfully loaded in mTi3C2Tx. SEM testing showed that the synthesized CeNPs @MXene filler had good dispersion and compatibility in polyurethane. According to the results, CeNPs, mTi3C2Tx, and CeNPs @mTi3C2Tx could enhance the anti-corrosion efficiency of waterborne polyurethane and prolong the anti-corrosion time. At the same time, WPU/CeNPs @ mTi3C2Tx exhibited an order of magnitude higher low-frequency impedance modulus than pure waterborne polyurethane and shown superior corrosion resistance over WPU/mCeNPs and WPU/mTi3C2Tx. The best anti-corrosion performance was achieved when the content of CeNPs @mTi3C2Tx was 1.5 wt%. The |Z|0.01Hz value was still close to 108 Ω·cm2 after 120 days of immersion.

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.

Photoactive coating based on waterborne polyurethane and carbon quantum dots as a prevention strategy for bacterial resistance

This study aims to develop photoactive coatings based on carbon quantum dots (CQDs) and waterborne polyurethane (WPU), capable of preventing the formation of bacterial biofilms. CQDs synthesized by microwave-assisted pyrolysis showed spherical morphology with an average size of 10.6 ± 3.1 nm, containing chemical groups with oxygen and nitrogen on the peripheral surface and photoluminescence at 460 nm and quantum yield of 63.2 % under excitation at 360 nm. Subsequently, CQDs were incorporated during WPU polymerization to form nanocomposites. The WPU/CQDs nanocomposites showed superior mechanical, rheological, and thermal properties concerning the pure WPU, due to the interaction of the nanoparticles with the polymeric matrix. The nanocomposites exhibited transparency and high photoluminescence, confirming the efficiency of the polymeric matrix in protecting the nanoparticles against photoluminescence extinction in the solid state. In addition, the WPU nanocomposite generates reactive oxygen species (ROS) after irradiation with blue light. The materials did not show cytotoxicity for BALB/3T3 murine fibroblasts after 24 h incubation. After illumination, the nanocomposite showed photodynamic activity against Pseudomonas aeruginosa (Gram-negative), thus validating its potential as a photoactive coating with sterilizing properties.

Preparation and corrosion resistance of KTNT–waterborne polyurethane coatings

In this study, titanate nanotubes (TNTs) were prepared through the hydrothermal method and then modified with γ-aminopropyltriethoxysilane (KH550) to obtain KTNTs with good dispersion properties. A KTNT–waterborne polyurethane (WPU) composite coating was prepared by blending KTNTs with WPU. Fourier transform infrared spectroscopy was used to characterize TNT compositions before and after modification. Thermogravimetric analysis and electrochemical impedance spectroscopy were used to test the thermal stability and corrosion resistance of the composite coating. The results showed that KH550 was successfully connected to the TNT surface. This improved the thermal stability and corrosion resistance of the KTNT–WPU coatings. The fastest thermal decomposition rate for the 0.5% KTNT composite coating was 2%/min lower than that of the pure WPU coating. At the same time, the impedance of the composite coating could reach 7.58 × 107 Ω cm2, the corrosion current density was 3.20 × 10−9 A/cm2 and the corrosion inhibition rate reached 99.87%. The composite coating had an effective corrosion protection time of 120 h, and the protective effect of the coating weakened when the immersion time exceeded 360 h.

Nanocellulose-reinforced polyurethane as flexible coating for cork floor

Cork materials have the property of elastic deformation under pressure due to their unique closed, porous, cell structure with thin cell wall; and they accordingly need a surface coating that matches their deformation during there being used as floor materials. However, traditional wood coatings are hard, brittle, and mostly suitable for stiff wood surfaces, which are difficult to be directly adapted to the requirements of flexible cork. Although waterborne polyurethane (WPU) has the advantage of property tailorability, its fully applicable to cork materials are still a challenge. Herein, this study utilized a simple physical blending of waterborne polyurethane and nanocellulose with high aspect ratio, to develop a high-strength coating that matches the elastic deformation requirements of cork materials. When both two kinds of nanocellulose, poplar wood nanocellulose (WCNF) with an aspect ratio of 800 and bacterial nanocellulose (BCNF) with an aspect ratio of 2000, was individually added into the WPU emulsion at 0.5 wt%, the tensile strength and elastic modulus of the nanocellulose-modified polyurethane coating increased by 48.58 % and 118.88 %, 54.50 % and 120.48 %, respectively, compared to those of the pure WPU coating (14.09 MPa and 312.74 MPa). It is notable that both the nanocellulose-modified coatings showed no signs of damage on the cork surface even they underwent continuous bending over 2000 cycles, which indicates their excellent flexural fatigue resistance. Interestingly, such nanocellulose-modified coatings maintain comparable transparency, gloss, adhesion, solvent resistance and even present slightly improved hardness and wear resistance than their pure WPU coatings. Overall, the two nanocelluloses are comparative to the modification of the coatings, both of which could match the elastic deformation requirements of cork materials. Therefore, the nanocellulose physically blended polyurethane technology provides a simple and effective solution for the design and property tailoring of flexible coatings for cork floor.

Synthesis of Carboxyl Cellulose Nanocrystals/Copper Nanohybrids to Endow Waterborne Polyurethane Film with Improved Mechanical and Antibacterial Properties

The multifunctional nanohybrid fillers have attracted widespread attention in the field of polymer nanocomposites. In this study, carboxyl cellulose nanocrystals/copper nanoparticles (TCNC/Cu NP) nanohybrids were prepared by in situ growth of copper ions on the modified carboxyl CNC, and further doped into waterborne polyurethane (WPU) via solution blending. TEM, FTIR, XRD, and UV–vis analysis were used to characterize the morphology, composition, crystallization and structure of the as-prepared nanohybrid. TCNC/Cu NP nanohybrids exhibited good dispersion and interface compatibility in WPU matrix. The nanocomposite film obtained significantly enhanced mechanical, thermal stability and scratch resistance properties, which was attributed to a hydrogen bond network structure formed in the WPU matrix. Additionally, colony count method was performed to test antibacterial properties of various films. Compared to the pure WPU film, all of nanocomposite films showed better antibacterial properties against Escherichia coli and Staphylococcus aureus. The antibacterial ratio of the WPU nanocomposite film with the addition of TCNC/Cu NP (1:1) reach 99%. Furthermore, the results of a copper ion sustained release experiment showed that the nanocomposite film had a long-term release effect, which was ascribed to the strong bonding between TCNC/Cu NP nanohybrids and WPU matrix. Thus, Cu NP was firmly embedded in the hydrogen bonding network structure formed. This work gives a new approach to prepare the antibacterial WPU film with well mechanical properties.

Low-loading oxidized multi-walled carbon nanotube grafted waterborne polyurethane composites with ultrahigh mechanical properties improvement

The uniform dispersion of oxidized multi-wall carbon nanotubes (OCNT) in waterborne polyurethane (WPU) matrix was achieved by in-situ polymerization, endowing the OCNT/WPU composite film with enhanced tensile strength, thermal stability, and excellent elongation at break. The structure of multi-wall carbon nanotubes (CNT) and OCNT was characterized by TEM, XRD, XPS, and the structure and morphology of composites were characterized by particle size analysis, SEM and FT-IR. Compared with pure WPU and OCNT/WPU composite, the breaking strength and the thermal degradation temperatures of 20 % weight loss of the OCNT/WPU composite were increased by 175 % and 353 °C, respectively. The oxygen-containing functional groups effectively improved the surface active of OCNT, making it easier for OCNT to react with polyurethane prepolymers. After addition of only 1 % OCNT, the tensile strength approaches 77 MPa while the elongation at break remains at 277 %. In addition to having outstanding chemical and mechanical properties, OCNT have a better dispersibility rate than multiwalled carbon nanotubes, which means that they will have a broader application range. • By in situ polymerization, oxidized carbon nanotubes are grafted into polyurethane systems. • Oxidized carbon nanotubes offer better performance than pristine carbon nanotubes. • Adding 1 % oxidized carbon nanotubes to waterborne polyurethane improved mechanical properties by 175 %.

Preparation, properties, and mechanism of anionic and cationic cellulose nanocrystals/waterborne polyurethane composite films

Three kinds of cellulose nanocrystals (CNCs) were added into waterborne polyurethane (WPU) and nanocomposite films that were prepared by solution casting. The influence of different ionic function groups on microstructure and properties of composite films was investigated. Compared with sulfated CNCs (SCNCs) and TEMPO oxidized CNCs (TOCNCs), FE-SEM images showed that cationized CNCs (CaCNCs) had better dispersion in composite films. The thermal decomposition of these composite films was delayed by 15 °C compared with pure WPU film. The tensile strength and fracture work of CaCNC/WPU composite film increased by 11.9% and 8.4%, respectively. The light transmittance of CaCNC/WPU composite film was highest among the 3 composite films, but its oxygen permeability was the lowest. In sum, the composite film with CaCNCs had optimal strength, toughness, light transmittance, and oxygen barrier properties, which is consistent with good compatibility of the two components and densest structure observed in SEM. There may be an ionic attraction and hydrogen bonds of CaCNCs and WPU in the composite film. The composite films are expected to have applications in food packaging, furniture coatings, and biomedical fields.

Synthesis of P, N and Si-containing waterborne polyurethane with excellent flame retardant, alkali resistance and flexibility via one-step synthetic approach

To endow pristine waterborne polyurethane with excellent flame retardation without reducing the mechanical properties, a flame retardant waterborne polyurethane with phosphorus, nitrogen and silicon units (P-N-Si-WPU) with excellent alkaline resistance was successfully synthesized by one-step synthetic approach, which it is conducive to realizing industrialization and avoiding many unnecessary side-reactions. In contrast to pure waterborne polyurethane, the limiting oxygen index value of P-N-Si-WPU is demonstrated to be increased from 18 % to 27.5 %. The peak heat release rate of P-N-Si-WPU is decreased from 648 W/g to 262.4 W/g. All results demonstrate that the possible flame retardant mechanism of P-N-Si-WPU is gas phase flame retardant and condensed phase flame retardant. During the decomposition of P-N-Si-WPU, a thermally stable char layer consisting P (=O)-O-Si- structure is formed to endow the P-N-Si-WPU with better thermal insulation ability in the combustion process. At the same time, due to the flexibility of Si-O-Si bond, the flame retardant and mechanical properties of the film can be balanced in the process of synthesis of waterborne polyurethane, which provides a strategy for the preparation of outstanding flame retardant waterborne polyurethane.

Properties and Fabrication of Waterborne Polyurethane Superhydrophobic Conductive Composites with Coupling Agent-Modified Fillers.

The addition of abundant fillers to obtain conductive and superhydrophobic waterborne polyurethane (WPU) composites generally results in increased interfaces in the composites, leading to reduced adhesion and poor corrosion resistance. Fillers such as Polytetrafluoroethylene (PTFE) and multi-walled carbon nanotubes (MWCNTs) were first treated by a coupling agent to reduce the contents of the fillers. Thus, in this work, WPU superhydrophobic conductive composites were prepared using electrostatic spraying (EsS). The polar groups (-OH and -COOH, etc.) on the WPU, PTFE, and MWCNTs were reacted with the coupling agent, making the WPU, PTFE, and MWCNTs become crosslinked together. Thus, the uniformity of the coating was improved and its curing interfaces were reduced, causing enhanced corrosion resistance. The dehydration reaction that occurred between the silane coupling agent and the polar surface of Fe formed -NH2 groups, increasing the adhesion of the coating to the steel substrate and then solving the problems of low adhesion, easy delamination, and exfoliation. With the increased content of the modified fillers, the conductivity and hydrophobic property of the composite were amplified, and its corrosion resistance and adhesion were first strengthened and then declined. The composite with the WPU, PTFE, MWCNTs, and KH-550 at a mass ratio of 7:1.5:0.1:0.032 held excellent properties; its volume resistivity and WCA were 1.5 × 104 Ω·cm and 155°, respectively. Compared with the pure WPU coating, its adhesive and anticorrosive properties were both better. This provides a foundation for the fabrication and application of anticorrosive and conductive waterborne composites.

Electrochemical deposition assisted the construction of titanium carbide@polyaniline hybrid in waterborne polyurethane conductive network for improved electromagnetic interference shielding and flame retardancy

To solve the increasing serious electromagnetic radiation pollution and limitations of metal-based electromagnetic shielding materials in flexible devices, the polyaniline (PANI) is deposited on the surface of two-dimensional Ti3C2 to obtain the Ti3C2@PANI hybrid for constructing waterborne polyurethane (WPU) composite. Meanwhile, to address the flame risk of WPU composite, the two-dimensional black phosphorous (BP) is incorporated as a flame retardant to prepare isolated flame-retardant black phosphorous-waterborne polyurethane/Ti3C2@polyaniline(Q-FBP-WPU/Ti3C2@PANI) composite with isolated structure. Due to the existence of conductive fillers and the isolated structure, the Q-FBP-WPU/Ti3C2@PANI composite exhibited the highest electrical conductivity (2.23 S/m) and the electromagnetic shielding effectiveness (EMI SE) of 27.3 dB in the frequency range of 8.2–12.4 GHz (X-band) and retains higher than 20 dB after hundreds of stretching and bending, which completely satisfies the commercial demands. Compared with the composite with a disordered structure, the thermal conductivity of Q-FBP-WPU/Ti3C2@PANI is increased by 93.3%. The cone test results show that the peak heat release rate, total heat release, total smoke production and total CO production of Q-FBP-WPU/Ti3C2@PANI is decreased by 46.2%, 16.3%, 21.2% and 15.5% than that of pure WPU, certifying the fire safety of WPU are greatly improved. This work supports a novel and applicable idea for constructing functional electromagnetic shielding materials.

Enhanced mechanical property, chemical resistance and abrasion durability of waterborne polyurethane based coating by incorporating highly dispersed polyacrylic acid modified graphene oxide

The incorporation of graphene oxide (GO) into waterborne polyurethane (WPU) coating shows great potential in enhancing the performance of WPU coating. But homogeneous dispersion of GO in polymer matrix is still a challenge for the application of GO. In this paper, the polyacrylic acid modified graphene oxide (PAA-nGO) with high dispersion stability in a wide range of pH (4–11) was prepared via two step amidation reaction. Significantly, PAA-nGO can be uniformly dispersed in WPU as bifunctional additive to prepare WPU/PAA-nGO coatings with enhanced mechanical property, chemical resistance and abrasion durability. The as-prepared WPU/PAA-nGO coating exhibited improved tensile strength (18.12 MPa) and tear strength (38.07 kN/m), which were 56.1% and 51.5% higher than those of pure WPU coating, respectively. Interestingly, WPU/PAA-nGO coating showed improved chemical resistance. Notably, abrasion durability of WPU/PAA-nGO coating was significantly enhanced, and the mass loss rate was decreased by 77.1%. Overall, this work provided a potential strategy for improving the mechanical property, chemical resistance and abrasion durability of WPU based coatings by introducing PAA-nGO with well dispersion and high stable in a wide pH range.

Highly effective anti-corrosion composite coatings enhanced by non-covalent functionalized boron nitride nanosheets via a facile latex approach

Boron nitride nanosheets (BNNSs)/polymer composite coatings with highly effective corrosion resistance have promising applications in metal surface protection. However, BNNSs tend to aggregate in waterborne polymer matrix, which degrades anticorrosion. Herein, a facile and effective method was developed to fabricate a stable latex containing non-covalently modified BNNSs through in situ polymerization of styrene in emulsion system, and waterborne polyurethane (WPU) composite coatings were sequentially constructed for the purpose of corrosion protection via latex blending. The developed composite coating (BNNSs@PS/WPU) exhibited a significantly improved impedance by 4 orders of magnitude after 28 days of immersion compared with pure WPU coating. Such outstanding anti-corrosion properties can be ascribed to the comprehensive action of BNNSs@PS composite latex, of which the PS microspheres can not only effectively prevent BNNSs from coalesce, but also act synergically with BNNSs that effectively retard the permeation of corrosive medium to the metal surface.