Polynorbornene/fluorosilica hybrids for hydrophobic and oleophobic coatings

Polynorbornene dicarboxylic anhydride (PNA)/fluorosilica hybrid coating materials with good hydrophobicity, oleophobicity, transparency, thermal stability, and hardness were synthesised using a sol–gel method. The surface structure, transparency, hydrophobicity, oleophobicity, and surface free energy of the coating could be controlled by adjusting the fluorosilane ratio. The maximum static water and oil contact angles of films were 112° and 87°, respectively. The PNA/fluorosilica hybrid films exhibited good transparency and colourlessness. The marks written using water and oil-based pens on the films could be erased with a tissue even after eight times. In addition, the hardness of the hybrid films was enhanced to 4H with increasing fluorosilane content.     

Improving hydrophobicity of polyurethane by PTFE incorporation

A simple and facile method was established of incorporating polytetrafluoroethylene (PTFE) on to polyurethane (PU) to improve hydrophobicity of PU by incorporating low levels of fluorine at a molecular level. Nanocomposites were made by preparing PU in the presence of PTFE using seeded miniemulsion polymerization method. The resulting PTFE/PU nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, differential scanning calorimetric, and thermo gravimetric analysis (TGA). FTIR and TEM indicated changes observed in their structure, size and morphology. The water contact angle of PTFE/PU nanocomposite films increased with increasing amount of PTFE and more on blending with silica nanoparticles but a slight decrease in thermal stabilities of SiO₂/PTFE/PU nanocomposites were noticed. The hydrophobicity imparted by PTFE to PU surface was found to be at its best for 1 : 2 PTFE/PU latex film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42779.     

Production of superhydrophobic polymer fibers with embedded particles using the electrospinning technique

Superhydrophobic materials are currently used for their water‐repelling, self‐cleaning and anti‐fouling properties but are also potentially attractive to prevent snow or ice accumulation on exposed structures. Using the electrospinning technique, polymer mats made of polystyrene and poly[tetrafluoroethylene‐co‐(vinylidene fluoride)‐co‐propylene] (PTVFP) were prepared. They were found to show highly hydrophobic properties, water contact angle (CA) between 130 and 150°, when a dual fiber–bead microstructure was observed. Superhydrophobicity, CA > 150°, was reached when PTVFP mats were electrospun from a polymer solution containing dispersed polytetrafluoroethylene (PTFE) nanoparticles. Using atomic force microscopy imaging, protruding nanosized asperities on fiber and bead surfaces were observed and this structure led to superhydrophobic properties. Materials prepared from a high‐viscosity PTVFP/ethyl acetate solution with PTFE particles, 200 nm diameter and 8% (w/w), showed an 11.2% improvement in hydrophobicity, CA = 161°, compared to the materials obtained from a particle‐free polymer solution (CA = 143°). Copyright © 2007 Society of Chemical Industry     

Study on preparation and anticorrosive performance of a new high hydrophobic anticorrosive coating

Water-based anticorrosive coatings have poor water resistance, which easily lead to coating deterioration and metal corrosion. In order to improve the anticorrosion performance of waterborne coating, herein, the polytetrafluoroethylene/dimethyl siloxane/epoxy resin (PTFE/PDMS/EP) hydrophobic anticorrosive coating was prepared by layer-by-layer construction. The spatial structure and microscopic morphology of the hydrophobic coating were analyzed by XRD, FTIR, and SEM. The hydrophobicity and corrosion resistance of the composite coating were analyzed by hydrophobicity test, electrochemical polarization curve, hydrophobicity and corrosion resistance test of the mixed layer, Tafel polarization curves, and AC impedance spectrum. The results showed that the water contact angle of PTFE/PDMS/EP coating reached 141° and the protection efficiency of PTFE/PDMS/EP coating was 98.62%. After soaking for 7 days, the corrosion process still stays at the initial stage, which was mainly due to the good sealing and barrier properties and high anticorrosion efficiency of PTFE/PDMS/EP coating. The coating has high corrosion protection efficiency and long service life, which is of great significance to metal corrosion protection in harsh marine environments.     

One‐step fabrication of fluoropolymer transparent films with superhydrophobicity by dry method

Fluoropolymer transparent thin films were deposited on different substrates by one‐step vacuum evaporation method, which exhibit superhydrophobic property with water contact angle (CA) greater than 150°. Polytetrafluoroethylene (PTFE) film with network structure shows high oleophobicity with oil CA of 138°, whereas polytetrafluoroethylene‐perfluoropropylvinylethers (PFA) film with particle structure is superoleophilicity with oil CA near 0°. It is believed that different conformation of  CF₂ groups at the surface lead to this different surface activity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高频天线罩防油污涂层应用研究

雨水或油污在天线罩上成膜会造成天线效率的降低。疏水疏油的易清洁涂层可有效降低雨水和油污在天线罩上的附着时间和附着力,可以起到自清洁的作用。本文选取了 3种不同种类的涂层体系,分别进行了疏水疏油性能评价、高频透波率测试和耐候性环境适应性验证。结果表明：所选的纳米涂层系统在疏水疏油、高频透波性和耐候性方面综合性能优异,适合在有疏水和防油污需求的天线罩上使用。     

Hydrophobic composite coatings with photocatalytic self-cleaning properties by micro/nanoparticles mixed with fluorocarbon resin

A newly developed hydrophobic composite coating was fabricated by incorporating modified TiO₂ nanoparticles and hydrophobic material polytetrafluoroethylene (PTFE) micropowders dispersed in fluorocarbon resin. Moreover, the surface characteristics and self-cleaning properties of the newly developed composite material were examined. The material was found to exhibit sufficient hydrophobicity with a water contact angle of 133°. The surface free energy of the composite coating was 4.11 mJ/m². Scanning electron microscopy results revealed a micro/nanocomposite structure composed of PTFE micropowders and TiO₂ nanoparticles, which was verified by X-ray photoelectron spectroscopy results. Through ultraviolet irradiation the modified TiO₂-PTFE/FEVE composite coating successfully removed oleic acid absorbed on its surface. These results showed that the functional composite coating had a sufficiently hydrophobic surface with an efficient self-cleaning effect.     

HTPB‐based polyurethaneurea membranes for recovery of aroma compounds from aqueous solution by pervaporation

Hydroxyterminated polybutadiene (HTPB)‐based polyurethaneurea (PU), HTPB‐PU, was synthesized by two‐step polymerization and was firstly used as membrane materials to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the number–average molecular weight (M_n) of HTPB, EA in feed, operating temperature, and membrane thickness on the PV performance of HTPB‐PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high EA flux. The DSC result showed two transition temperatures in the HTPB‐PU membrane and contact angle measurements revealed the difference of hydrophobicity of the membrane at both sides, which were induced by glass plate and air, respectively, due to movement of the soft hydrophobic polybutadiene (PB) segments in HTPB‐PU chains. Furthermore, the PV performance of the HTPB‐PU membrane with the hydrophobic surface facing the feed was much better than that with the hydrophilic surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 552–559, 2007     

Synthesis and characterization of a novel polyurethane curing agent modified by a diazafluorene derivative

In this study, we synthesized a novel polyurethane (PU) curing agent (CA) modified by the diazafluorene derivative, 9,9′‐di(4‐hydroxyphenyl)‐9‐1H‐4,5‐diazafluorene, at different hydroxyl ratios. The results of ¹H‐NMR and Fourier transform infrared spectroscopy proved the structure of the fluorine derivative and the modification of CAs. Differential scanning calorimetry and dynamic mechanical analysis showed that the glass‐transition temperature of the PU increased with the addition of the diazafluorene derivative, and the PU cured in the novel CA had more stable and better damping properties under moderate‐temperature conditions (30–80 °C) than the PU cured in the N75 CA. Tan δ was maintained in a relatively lower range shift in the moderate‐temperature range. The average adhesion values of the PU coating cured in the novel CA increased. The scanning electron microscopy morphologies of the PU film and the average adhesion of the coatings showed that the PU cured in the novel CA had good mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46591.     

Aerosol-deposited Al2O3/PTFE hydrophobic coatings with adjustable transparency

With the wide range of requirements for architectural glass, such as transparency, opacity, and hydrophobicity, there is a need to address the issues in the complexity of convention methods. Thus, considering functionality and applicability in various architectural windows, hydrophobic alumina/polytetrafluoroethylene (Al₂O₃/PTFE) composite layers with transparency or opacity were transferred to commercial architectural glass using a facile aerosol deposition (AD) process. We successfully fabricated hydrophobic coating layers with high transmittance (only a 0.03% difference from sheet glass) by optimizing the PTFE content in Al₂O₃ using solution-based synthesized powders to enable a uniform surface topology. The opaque hydrophobic Al₂O₃/PTFE coating layers exhibit a transmittance of approximately 0% with excellent hydrophobicity of 130°. Remarkably, this opaque film was successfully employed onto a large deposition area, curved substrate, and micro-patterned regions. It is believed that our AD-prepared composite layers have great potential for architectural glass in terms of economic feasibility and versatility.     

Blood compatibility and physicochemical assessment of novel nanocomposite comprising polyurethane and dietary carotino oil for cardiac tissue engineering applications

Cardiovascular diseases (CVD) were estimated to claim 17 million lives each year. Among these, coronary heart disease almost accounts 50% deaths associated with CVD, which causes the blockage of the coronary arteries that supplies blood to the heart. Nowadays, the cardiac tissue engineering have become a promising solution to overcome the drawbacks associated with current therapies. Further, the scaffold used in cardiac tissue engineering must possess thromboresistant and anticoagulant nature to serve as a plausible candidate for cardiovascular applications. In this present investigation, a novel nanocomposite based on polyurethane (PU) and carotino oil was fabricated using electrospinning. Scanning electron microscopy images indicated that the nanocomposites have smaller fiber diameter (702 ± 130 nm) compared to the pristine PU (969 ± 217 nm). The Fourier transform infrared spectroscopy analysis confirmed the interaction between the carotino oil and PU by the formation of hydrogen bond and shifting of CH peak. The contact angle of electrospun PU/carotino oil was found to be 119°, which was increased compared to pristine PU (86°) indicating the hydrophobic nature of developed nanocomposites. Moreover, the surface roughness and thermal stability were found to be enhanced due to the presence of carotino oil in the PU matrix indicated in atomic force microscopy and thermogravimetric analysis. The enhanced surface roughness of nanocomposites resulted in delayed activation of the blood clot as revealed in activated partial thromboplastin time and prothrombin time assay. Moreover, the hemolytic index of fabricated nanocomposites was found to very low of about 1.33% compared to pristine PU (2.73%), suggesting non‐hemolytic nature and also better blood compatibility. So, the developed PU/carotino nanocomposites having desirable characteristics like better physicochemical and blood compatibility may render appropriate potentials for raw materials of cardiac tissue engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45691.     

Preparation,characterization, and influence of polyurea coatings on their layered composite materials based on flexible rebonded polyurethane

Preparation and characterization of a series of polyurea (PU) coatings and their influences on layered composite materials based on rebonded polyurethane (PUr) for floor application are described in terms of the raw materials, formulation, and application performance. While PU coatings show almost the same FTIR peaks, thermogravimetric analyses results reveal that thermal stabilities of the PU coatings are slightly enhanced with the use of trifunctional polyamine compound and one step degradation takes place beyond 300°C. All PU coatings have very dense, smooth, and bubble-free surfaces whereas the cross-sectional SEM images exhibit pores of different sizes. Contact angle values of all PU coatings are bigger than 90° indicating that the surfaces are hydrophobic. Using propylene carbonate in the preparation of methylene diphenyl diisocyanate (MDI) prepolymer and the chain extender in the PU coating formulation impacts the mechanical and electrical properties of the PU coatings as well as layered PU/PUr composite materials. In conclusion, not only the controllable physicochemical and mechanical properties of layered PUr/PU composites but also the usage potential of recycled PU scraps in these layered composites are very promising for better floor applications.     

Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO₂) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO₂ was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO₂ and modified SiO₂ were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO₂ and modified SiO₂ on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO₂ and modified SiO₂ was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO₂‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature (T_g) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry     

Improving hydrophobicity on polyurethane-based synthetic leather through plasma polymerization for easy care effect

This study reports on the deposition of a hydrophobic coating on polyurethane (PU)-based synthetic leather through a plasma polymerization method and investigates the hydrophobic behavior of the plasma-coated substrate. The silicon compound of hexamethyldisiloxane (HMDSO), inactive gas argon (Ar), and toluene were used to impart surface hydrophobicity to a PU-based substrate. Surface hydrophobicity was analyzed by water contact angle measurements. Surface hydrophobicity was increased by deposition of compositions of 100% HMDSO, 3:1 HMDSO/toluene, and 1:1 HMDSO/toluene. Optimum conditions of 40 W, 30 s plasma treatment resulted in essentially the same initial contact angle results of approximately 100° for all three treatment compositions. The initial water contact angle for untreated material was about 73°. A water droplet took 1800 s to spread out on the plasma-treated sample after it had been placed on the sample surface. An increase in plasma power also led to a decrease in contact angle, which may be attributed to oxidization of HMDSO during plasma deposition. XPS analysis showed that plasma polymerization of HMDSO/toluene compositions led to a significant increase in atomic percentage of Si compound responsible for the hydrophobic surface. The easy clean results for the treated and untreated PU-based synthetic leather samples clearly showed that the remaining stain on the plasma-polymerized sample was less than that of untreated sample. The plasma-formed coating was both hydrophobic and formed a physical barrier against water and stain.     

紫铜为基材用化学复合镀法制备Ni-P-聚四氟乙烯疏水性膜

采用化学复合镀的方法,以紫铜为基材,制备复合材料Ni-P-聚四氟乙烯(PTFE)疏水性膜;控制镀液的组成和条件,可获得具有良好疏水性的复合材料Ni-P-PTFE膜,其与蒸馏水接触角为128.6°;原子力显微镜扫描图像表明,表面微粒分布均匀,表面由许多微小的结构覆盖;XPS光电子能谱分析结果表明镀层组成Ni,P,PTFE质量分数约为52.68%。     

Scalable non-solvent-induced phase separation fabrication of poly(vinylidene fluoride) porous fiber with intrinsic flame-retardation and hydrophobic properties

Advanced fibrous materials with intrinsic functional properties have been recognized as research hotspots in the field of functional fibers. Poly(vinylidene fluoride) with intrinsic flame-retardation and hydrophobic properties is the desirable fundamental material for functional fibers. In this paper, a novel poly(vinylidene fluoride) (PVDF) porous fiber endowed with flame retardation and hydrophobicity was fabricated through a continuous scalable wet spinning route. Based on non-solvent-induced phase separation theory, distilled water was employed as green non-solvent (coagulant solution) to solidify the nascent PVDF fiber. The morphology and structure of the resultant fibers were characterized by SEM, FTIR, XRD, BET, TG-DTG and DSC. The obtained fibers possessed similar diameter around 18 μm and numerous interlaced pore structure owing to phase separation. Two crystalline phases, α-PVDF and β-PVDF, of PVDF fibers were confirmed based on FTIR and XRD. The combustion performance and hydrophobic properties of PVDF porous fibers were evaluated by limiting oxygen index (LOI), cone calorimetry and contact angle, respectively. The results indicated that LOI of the PVDF fiber could reach 24.2, implying a remarkable flame retardation. Besides, the low density (0.86 g/cm³) and high contact angle (105°) of PVDF porous fibers endow durable floating and good hydrophobic properties. Therefore, PVDF porous fibers with remarkable intrinsic flame retardation and hydrophobicity can be recommended as a reasonable candidate for thermal-protective garment for life jackets.     

One-step preparation of asymmetric ceramic membranes based on sea urchin-like mullite whisker skeletons and their oil-water separation properties

In this work, novel sandwich-type asymmetric ceramic microfiltration membranes with a sea urchin-like mullite whisker skeleton were prepared one step. Their structural properties and oil-water separation performance were investigated. The results show that after sintering at 1400 °C, the prepared membrane possesses good hydrophilic, underwater oleophobic, and anti-fouling properties. During the continuous separation of a 300 mg/L oil-in-water emulsion, a maximum stable flux of 267 L·m⁻²·h⁻¹ was achieved without membrane cleaning. After chemical cleaning and simple physical cleaning, the membranes recovered to a steady flux of 397 L·m⁻²·h⁻¹ and 305 L·m⁻²·h⁻¹, respectively, and maintained a 95% oil rejection. The good underwater oleophobicity and selective permeability brought about by the flat-lying whiskers on the top surface, coupled with the efficient water channels between the sea urchin-like structures inside the membrane, are considered to be the main reasons for its improved separation characteristics over conventional low-cost ceramic membranes.     

Polyurethanes from 4,4′‐diphenylmethane diisocyanate and poly(ethylene glycol)s. II. Crystallographic data,heats of melting and crystallization,thermal stability,crystallinity and density

Wide‐angle X‐ray scattering analysis, heats of melting, crystallization and re‐melting, thermogravimetric analysis and density measurements have been used to study the crystallographic data and degree of crystallinity of linear polyurethanes (PUs) prepared by the polymerization of 4,4′‐diphenylmethane diisocyanate (MDI) with poly(ethylene glycol)s (PEGs) of various number‐average molecular weights (M_ns) (106, 200, 400, 1000, 2000 and 4000 g mol^?1) in equivalent molar ratios. The crystallinities of polyurethanes PU1000 to PU4000 are shown to be due to the polyoxyethylene segments of the PEGs, while PU400 and PU200 appeared to be amorphous. However, PU106, similarly prepared from diethylene glycol (PEG106), is highly crystalline with a different crystal structure. Thermogravimetric analysis of PU106, PU400 and PU1000 exhibited high thermal stabilities up to 260 °C for these materials under the conditions of measurement (10 °C min^?1). The heat of melting for the 100 % crystalline structure of PU106 has been indirectly obtained. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of microencapsulated ammonium polyphosphate and its synergistic flame‐retarded polyurethane rigid foams with expandable graphite

A facile and effective method for the preparation of microencapsulated ammonium polyphosphate (MAPP) by in situ surface polymerization was introduced. The ‘polyurethane‐like’ shell structure on the surface of MAPP was characterized by using Fourier transform infrared spectroscopy. The hydrophobicity and thermal behavior of MAPP were studied by using water contact angle tests and thermogravimetric analysis. The foam density and mechanical properties of polyurethane (PU) rigid foams were investigated. The flame retardancy of PU rigid foams formulated with MAPP was evaluated by using limiting oxygen index and cone calorimetry. The results show that MAPP can greatly increase the flame retardancy of PU materials. Also, there is a synergistic effect between MAPP and expandable graphite in flame retarding PU rigid foams. Moreover, the water resistance property of PU/MAPP composites is better than that of PU/ammonium polyphosphate. The morphology and chemical structure of PU/MAPP rigid foams after burning were systematically investigated. © 2013 Society of Chemical Industry     

Tribological properties of PTFE‐filled thermoplastic polyimide at high load,velocity, and temperature

The effect of 20 wt% polytetrafluoroethylene (PTFE) fillers on the friction and wear properties of thermoplastic polyimides (TP) are investigated, under dry sliding in line contact against steel under 50 to 200 N, 0.3 to 1.2 m/s, and 60 to 260°C. Besides the lubricating mechanisms of PTFE based on mechanical shear, the thermal and tribophysical interactions in the sliding interface are considered in this research by using thermoanalytical measurements, Raman spectroscopy, and calculating the maximum polymer sliding temperature T*. The effect of hydrolysis of the TP bulk material, causing high friction at 100 to 140°C, is covered by PTFE. A transition at pv‐values 2.2 MPa m/s (T* = 120°C) is due to thermally controlled sliding of PTFE, while a transition at pv‐values 3.2 MPa m/s (T* = 180°C) remains controlled by degradation of the TP bulk material into monomer fractions. The reduced coefficient of friction in the presence of PTFE leads to smaller degradation and orientation of the molecular back‐bone and side‐chains within the TP structure. The formation of a homogeneously mixed transfer film is only observed at 180 to 260°C. The PTFE forms a fibrillar structure during wear at high sliding velocities, while they wear as separate particles at high normal loads. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers