Good Hydrophobic Properties Research Articles

Novel biobased epoxy resin thermosets derived from eugenol and vanillin

Novel renewable bisepoxide 2, 2′-diglycidyl ether-3, 3′-dimethoxy-5, 5′-diallydiphenylmethane (BEF-EP) and its hardener 3-methoxy-4-hydroxy-phenylbenzimidazole (VBZMI) were prepared from 1-allyl-3-methoxy-4-hydroxybenzene (eugenol) and 2-methoxy-4-formylphenol (vanillin), respectively. The chemical structures of two monomers were confirmed by their 1H NMR spectra. Estrogenic activity test revealed that biobased bisphenol monomer 2,2′-dihydroxy-3,3′-dimethoxy-5,5′-diallydiphenylmethane (BEF) as the precursor of BEF-EP showed an extremely lower estrogenic activity than commercial bisphenols (BPA and BPF). This biobased, safe and green epoxy (BEF-EP) and commercial epoxy diglycidyl ether of bisphenol F (BPF-EP) were then cured with conventional and renewable hardener (benzimidazole BZMI and 3-methoxy-4-hydroxy-phenylbenzimidazole VBZMI), respectively, for comparison. The results showed the biobased epoxy thermoset (BEF-EP/BZMI) possessed excellent thermal stability (Td5% = 372 °C), almost reaching the properties of commercial epoxy thermoset (BPF-EP/BZMI, Td5% = 385 °C). Furthermore, BEF-EP/BZMI showed good hydrophobic properties, which exhibited a higher contact angle (79.53°) than BPF-EP/BZMI (75.16°). In addition, for the comparison between VBZMI and BZMI, the epoxy resins using VBZMI as the curing agent displayed higher performance than the epoxy resins using BZMI as the curing agent. Especially, BEF-EP/VBZMI showed a higher thermal stability (Td5% = 395 °C), a higher glass transition temperature (Tg = 97 °C) and a higher contact angle (94.07) than BEF-EP/BZMI. The results could be attributed to the existence of hydroxyl groups in the side chain of VBZIMI, which enhanced the crosslinking density and then improved the rigid of epoxy material. Herein, we believe the novel biobased epoxy resin (BEF-EP) and hardener (VBZMI) has wide application as the alternative of conventional petroleum-based epoxy resin and hardener.

The reactive compatibilized effect of SMA for immiscible APA6/PS blends via in-Situ polymerization

Styrene maleic anhydride (SMA)-g-APA6 copolymer was firstly synthesized by free radical polymerization of styrene and followed by anionic polymerization of ε-caprolactam. The polyamide 6 (APA6)/polystyrene (PS) blends were successfully prepared via anion polymerization. Among in, SMA was acted as both compatibilizer and macromolecular activator. A series of APA6/PS blends with different SMA addition amounts were synthesized to study the effect of SMA on crystallinity, morphology, water resistance, thermal stability and mechanical properties using X-ray diffraction analysis, differential scanning calorimetry, scanning electron microscopy analysis, contact angle measurement, water absorption measurement, molau test, thermogravimetric analysis, stretching and impact test. Correlational analysis proved that the obtained SMA-g-APA6 copolymer has good dispersion with PS. In addition, APA6/PS blends possess good mechanical properties, thermostability and hydrophobic property.

The study of wettability in reduced graphene oxide film on copper substrate using electrostatic spray deposition technique

We report the preliminary study of wettability properties of reduced-graphene oxide (rGO) film prepared by electrostatic spray deposition technique. Wettability is an important property in surface material that can drive the direction of development for various applications. The experiments were performed using copper plate as substrate and graphene oxide (GO) solution of 4 mg/ml as coating material. We examined and investigated the effect of various high voltages to surface morphology and wettability of rGO. The voltages are varied at 1.0 and 1.5 kV and substrate temperature was fixed at 150°C. The rGO film was obtained through thermal treatment of GO film at 200°C for 1 hour. The surface morphology of rGO films were examined using optical microscope and scanning electron microscope. The wettability was examined using static contact angle method to determine water contact angle. The results show that the surface roughness and water contact angle of rGO film was affected by deposition voltage. The highest water contact angle of rGO film of 123.98° that indicated good hydrophobic properties was obtained for deposition condition on 1.5 kV.

Facile preparation of superhydrophobic silica nanoparticles by hydrothermal-assisted sol–gel process and effects of hydrothermal time on surface modification

Superhydrophobic silica nanoparticles were prepared by hydrothermal-assisted sol–gel process using a two-step synthesis route. Silica nanoparticles were obtained by hydrolysis and condensation of tetraethyl orthosilicate (TEOS). Hexadecyltrimethoxysilane (HDTMS) was added to allow the condensation reaction between HDTMS hydroxyl group and silica hydroxyl group, rendering silica particles hydrophobic. Silica nanoparticles had a HDTMS/TEOS molar ratio of 2:40 and exhibited good hydrophobic property with a high water contact angle of 156.1°. Water droplet rolled off the surface of silica powder owing to a low sliding angle of 3.6°. When hydrothermal time of TEOS decreased from 120 to 60 min, all silica powders gave rise to high water contact angles (≥154.8°) and low sliding angles (≤5.5°). However, silica powder became hydrophilic when HDTMS and TEOS were added to the precursor together. This facile preparation of superhydrophobic silica nanoparticles with short reaction time provided the advantages for potential application in industrial production.

Development of forcespun fiber-aligned scaffolds from gelatin-zein composites for potential use in tissue engineering and drug release

Abstract

Self‐Cleaning and Antibacterial Zeolitic Imidazolate Framework Coatings

AbstractSuperhydrophobic surface with self‐cleaning function like lotus leaf can inhibit bacterial adhesion to some extent; however, it cannot completely avoid bacterial contamination because it could not kill them. In this work, a facile modified sol–gel method to prepare self‐cleaning and antibacterial coating is proposed. Zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles with good hydrophobic and antibacterial properties are mixed with polyvinylidene fluoride (PVDF) colloidal particle suspension, then, the PVDF/ZIF‐8 nanocomposite is modified with 1H, 1H, 2H, 2H‐perfluorooctyltriethoxysilane (POTS) to prepare PVDF/ZIF‐8/POTS (PZP) coating solution. The resultant PZP nanocomposite coatings have a high contact angle (>160°) and a low sliding angle (<7°). Meanwhile, it is found that the dirt particles accumulated on the surface can be easily washed off by rolling water droplets, demonstrating its superb self‐cleaning function. Notably, the PZP nanocomposite coating shows excellent antibacterial activity against Gram‐negative Escherichia coli. These ZIF‐8‐based nanocomposite coatings with superb self‐cleaning function and high antibacterial activity denote their great potential in a wider range of practical applications.

Preparation, structure, and properties of an AlCrMoNbZr high-entropy alloy coating for accident-tolerant fuel cladding

A nearly equal molar ratio AlCrMoNbZr high-entropy alloy (HEA) coating was deposited on N36 zirconium alloy substrates using magnetron co-sputtering technology to enhance the corrosion resistance of light water reactor (LWR) fuel cladding. The microstructure, mechanical properties, surface wettability and corrosion resistance of the AlCrMoNbZr coating were systematically investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed that the AlCrMoNbZr HEA coating contained a composite of amorphous and bcc-structured nanocrystals. A nanoindentation test revealed that the coating had a high hardness of 11.8 GPa, and a scratch test indicated that the coating well adhered to the N36 substrate. The contact angle test showed that the static contact angle was 109°, which indicated the good hydrophobic property of the coating. The corrosion measurement showed that the AlCrMoNbZr coating remained effective after it was immersed in static pure water at 360 °C and 18.7 MPa for 30 days, and no N36 substrate oxides formed, which indicated a superior corrosion resistance. Furthermore, the corrosion behaviour of the coating was discussed. The weight gain measurement (8.8 mg/dm2 weight gain) proved that the coating experienced an oxidation process, and during the process, protective Nb2Zr6O17, ZrO2 and Cr2O3 formed on the surface of the coating. Hence, the AlCrMoNbZr HEA coating is a potential candidate material for accident-tolerant fuel (ATF) coatings.

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.

Zwitterionic–polyurethane coatings for non-specific marine bacterial inhibition: A nontoxic approach for marine application

The present work reports synthesis and development of zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings which are thermally stable and have hydrophobic properties which can be used for marine applications. The zwitterionic tri-block copolymer (ZTC) (poly(sulfobetaine methacrylate) - polydimethylsiloxane - poly(sulfobetaine methacrylate), polySBMA-block-PDMS-block-polySBMA) was synthesized by ATRP (atom transfer radical polymerization) method. Apart from this, the facile synthesis of silane functionalized acrylic polyol was formulated with 4,4′- Methylene dicyclohexyl diisocyanate (H12 MDI) for the development of polyurethane (PU) coatings. Different weight ratios of ZTC was incorporated in PU to obtain a zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings. The ZTC-PU coating exhibit good thermal stability and hydrophobic property. The coating showed excellent non-specific marine bacterial inhibition property along with good stability against gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) microbial strains. This design method reveals the development of zwitterionic-polyurethane coatings with higher amount of zwitterionic moiety in the coating system, that will be efficient and eco-friendly technology for marine bio-fouling application.

Molecular dynamics simulation of the aggregation behavior of N-Dodecyl-N,N-Dimethyl-3-Ammonio-1-Propanesulfonate/sodium dodecyl benzene sulfonate surfactant mixed system at oil/water interface

Molecular dynamics simulation method was used to study the aggregation behavior of the surfactant mixed system of N-Dodecyl-N, N-Dimethyl-3-Ammonio-1-Propanesulfonate(SB12-3)/Sodium Dodecyl Benzene Sulfonate(SDBS) at oil/water interface and the interaction between SB12-3 and SDBS. Radial distribution function (RDF) was used to investigate hydrophilic effects of SB12-3 and SDBS. Angles between the head groups and tail chains of surfactants and deuterium order parameter were used to study hydrophobic properties of the two surfactants. The simulation results showed that there were well synergistic effects between SDBS and SB12-3, and the synergistic effects reached maximum when the ratio of SDBS and SB12-3 was 4:6. There was strong interaction between −SO3− of SB12-3 and hydrogen atoms of water molecules. −N+ in SB12-3 preferentially approached to −SO3− in SDBS by the electronic interaction, making two surfactants intertwine with each other. The analysis results from angles and deuterium order parameter indicated the hydrocarbon chains of SDBS were prone to stretch in the oil phase, showing good hydrophobic properties. The synergistic effects between SDBS and SB12-3 resulted from the hydrophilic properties of SB12-3 had a complementary action with the hydrophobic properties of SDBS.

ZnO Nanoflakes on Pb Plates with Antibacterial Effects by Electrochemical and Hydrothermal Deposition

ZnO nanoflakes were grown on the lead (Pb) plates using the electro- hydrothermal deposition methods. To investigate the influence of electrodeposition current, the ZnO seed layer was electrodeposited on the lead plates at a larger current of 160 mA (current density of 40 mA/cm2) and a smaller current of 12 mA (current density of 3mA/cm2), respectively. Then, ZnO nanoflakes were grown on top of the seed layer. Multiple analyses including field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), photoluminescence (PL) were performed on the ZnO nanostructures/Pb plates. Furthermore, surface con-tact angle measurements were conducted to study the hydrophobic properties and OD 600 antibacterial tests were used to investigate the antiseptic effects. Results indicate that the ZnO nanoflakes with the seed layer grown at a lower current of 12 mA exhibited good hydrop-hobic properties and strong antibacterial effects. ZnO nanoflakes/Pb plates show promising for future anti-radiation, antibacterial, and waterproof lead clothing applications.

Analysis of the Cross-Linking Reaction of Lignin with Triethyl Phosphate by MALDI-TOF and 13C NMR.

The reaction of condensation and cross-linking of desulfurized kraft lignin with triethyl phosphate (TEP) was explored. Catechol, a simple model of the aromatic ring of lignin, and glycerol, a model compound of the aliphatic hydroyl groups of the side chain of lignin, were employed under similar reaction conditions. Solid state cross-polarisation/magic-angle spinning (CP-MAS) 13C NMR and matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) spectroscopy studies showed that polycondensation occurs on phenolic hydroxyl groups of lignin, as well as on aliphatic hydroxyls groups of its side chain. The reactions appear to be favoured by higher temperatures and in the presence of ammonia. Preliminary adhesion tests on wood shown good hydrophobicity properties of the surface treated with lignin-TEP-based resin. Initial application tests carried out at high temperature demonstrated as good performance as metallic coating.

Effect of PFOA on Oxidative Stress and Membrane Damage of Escherichia coli

Perfluorooctanoic acid (PFOA) is widely used in industrial production because of its strong chemical stabilities and good hydrophobic and oleophobic properties. It was considered to be a widespread persistent organic pollutant in environment in recent years. The oxidative stress and membrane damage of Escherichia coli exposed to PFOA were measured by flow cytometry (FCM) and the toxic mechanism of PFOA was also preliminarily explored. The results showed that, under the stress of PFOA, the intracellular reactive oxygen species (ROS) content of E. coli increased, the unsaturation degree of fatty acid decreased, the malondialdehyde (MDA) content increased, the membrane permeability increased, the membrane potential decreased, and the activities of Na+K+-ATPase and Ca2+Mg2+-ATPase showed a compensatory increase first and then decreased. Therefore, owing to the stress of PFOA, the higher intracellular ROS in E. coli reacted with membrane unsaturated fatty acids by peroxidation,and then reduced cell membrane fatty acid saturation, accumulated MDA in cells, and further caused damage to cell membrane, reduced the ATPase activity, and eventually resulted in inactivation or apoptosis of E. coli. This study provided more evidence for the further study on environmental ecological toxicology of PFOA.

Effects of Fluorine Atoms Amount and Fluorinated Acrylic Chain Length Chemically Attached to Hydroxyl Groups on the Hydrophobic Properties of Cotton Fabrics

A two-step chemical treatment of cotton fabric was performed with the attachment of fluorine moieties on hydroxyl group sites. The hydroxyl groups of cotton were initially acrylated by 2-isocyanaethyl methacrylate. Acrylic monomers, containing four to twelve fluorine atoms, had been used to build polymeric chain directly on the surface of cotton by means of radical polymerization. Fabrics became 10-20% stiffer and microscopy showed a clear change of the cotton surface after the treatment. Coated samples of cotton had shown hydrophobic property with a highest contact angle of 128 degrees. It was found that the increase of molecular weight of fluorinated polyacrylate on the cotton surface lowered contact angle value. The best results in hydrophobicity had been obtained at the molar stoichiometric ratio between the number of hydroxyl groups of cotton and the amount of fluorinated monomer added. This developed method allowed for the direct radical polymerization on cotton fabric, providing good hydrophobic properties with the formation of fluorinated polyacrylate of different molecular weights.

Functionalization of cotton fabrics through thermal reduction of graphene oxide

Graphene oxide (GO) was in-situ reduced on cotton fabrics by a simple heat treatment, which endowed cotton fabrics with multi-functions. GO was coated on the surface of cotton fabric through a conventional “dip and dry” approach. Reduced graphene oxide (RGO) was obtained from GO in the presence of cotton by heating under the protection of nitrogen. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy were employed to characterize the complexes of RGO and cotton (RGO/cotton). The RGO/cotton fabrics showed good electrical conductivity, surface hydrophobicity and ultraviolet (UV) protection properties. These properties did not deteriorate significantly after repeated fabric bending and washing.

Open‐cell polypropylene/polyolefin elastomer blend foams fabricated for reusable oil‐sorption materials

ABSTRACTThe fabrication of high‐performance oil sorbents is of great significance for oil spill cleanup. The main objective of this study was to prepare open‐cell polypropylene/polyolefin elastomer (PP/POE) blend foams for fabrication of reusable sorbents for oil sorption. Open‐cell PP/POE blend foams were prepared via continuous‐extrusion foaming using supercritical carbon dioxide as the blowing agent. The interconnected open‐cell structure was characterized by scanning electron microscopy. The hydrophobicity and lipophilicity of PP/POE open‐cell foams were revealed by tests of contact‐angle measurement, water and cyclohexane sorption on the foam surface, CCl4 and cyclohexane sorption in water, and oil/water separation. Further, the sorption tests indicated that PP/POE blend foams showed larger oil‐uptake capacities than pure PP foams. In addition, cyclic compression tests showed that PP/POE open‐cell foams had excellent ductility and significantly improved recoverability compared to pure PP foams. In cyclic sorption–desorption tests, the sorption kinetics was studied in terms of capacity and saturation time, showing that PP/POE foams kept larger sorption capacities for 10 cycles, with larger sorption rates and good reusability. Based on the high open‐cell content, the good hydrophobic and oleophilic properties, the high oil‐sorption capacity, the improved recoverability, the large sorption rate, and the good reusability in cyclic oil‐sorption performance, the PP/POE open‐cell foams have shown promise as potential oil sorbents in applications for oil spill cleanup. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43812.

Fabrication of self-cross-linking fluorinated polyacrylate latex particles with core-shell structure and film properties

A series of self-cross-linking fluorinated polyacrylate latex particles with core-shell structure were successfully prepared by one-step miniemulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), dodecafluoroheptyl methacrylate (DFMA), and γ-methacryloxypropyl triisopropoxidesilane (MPS). The core-shell structure of the latex particles was confirmed and the latex films were characterized. Results showed that the latex films not only showed enhanced thermostability but also exhibited good hydrophobic property with the incorporation of a small amount of MPS (below 5wt% of monomers). This core-shell fluorine/silicone-containing polyacrylate latex could potentially be used for developing advanced multifunctional protective coatings such as antiwetting, anti-icing, antifogging, and anticorrosion.

Experimental investigation on surface wettability of copper-based dry bioelectrodes

Laser micromilling technology was used to fabricate a dry bioelectrode with a surface microstructure array, which was then treated with stearic acid ethanol solution. A superhydrophobic dry bioelectrode was obtained. Based on the scanning electron microscopy results, the formation of the dry bioelectrode with a surface microstructure array had been discussed. Later, the contact angle on the bioelectrode surface was analyzed by changing the parameters such as laser processing parameters, spacing of microstructure, and the working media. The results show that the contact angle of the bioelectrode surface treated with stearic acid ethanol solution was approximately 151°, and this value was compared with the result for bioelectrodes that were not treated or placed in air. The laser power and number of scans had significant influences on the contact angle, while the scanning speed had only a slight influence. When the spacing of microstructure was in the range of 0.1–0.5mm, the contact angle increased with a decrease in the spacing of microstructure. In addition, the contact angle on the bioelectrode with deionized water or saline water as the working media was greater than 150°. Our developed dry bioelectrode presented good hydrophobic properties to help to realize a stable measurement system over a long time, which has many applications in the detection and measurement of biological signals.

Evaluation on biocompatibility of biomedical polyurethanes with different hard segment contents

In this paper, polyurethane (PU) materials with different contents of hard segment (20%, 25%, 30%) were prepared based on hexamethylene diisocyanate and polycarbonate diols by solution polymerization. The obtained polycarbonate-urethane (PCU) elastomers were characterized by very good hydrophobic property and excellent resistance to hydrolysis. Hemolysis, recalification time and platelet-rich plasma adhesion were used to evaluate the blood compatibility of the materials. L929 cells cultured with leach liquor of these PU membranes were selected to perform the cytotoxicity experiments. The results indicate that the hemolysis rates of PU membranes are all less than 5%, which can meet the requirement of the national standards for biomaterials. However, compared with 20% and 30% groups, the recalification time of the sample containing 25% hard segment is longer, while the number of platelet adhesion is less. Additionally, cells cultured in the leach liquor of PU membranes with 25% hard segment proliferated relatively more thriving, meaning that this proportion of the material has the lowest cytotoxicity.

Nanoparticulated hydrophobic CdO coatings deposited by microwave procedure

A novel and inexpensive way to deposit nanostructured cadmium oxide (CdO) coatings is described. Metallic Cd is evaporated by heating a silicon carbide crucible, via microwave radiation at standard atmosphere conditions. The Cd vapour rises from the crucible and reacts with the atmospheric oxygen depositing on a glass substrate. CdO coating is homogeneously distributed above the glass surface and it presents a well-defined cubic-shaped nanostructure. The as-deposited CdO coatings showed good hydrophobic properties and achieved symmetric contact angles of 112°. The hydrophobic behaviour was lost after a 75 min of heat treatment at 723 K.