Hydrophobic Nanocomposites Research Articles

Eco-friendly fabrication of novel hydrophobic CMC–C18@MWCNTs nano-sorbent for fat content removal in the analysis of polycyclic aromatic hydrocarbons in fatty-food samples

In this study, carbon nanohybrids was developed by hybridizing carboxymethyl cellulose (CMC) biopolymer with various amounts of multi-walled carbon nanotubes (MWCNTs: 0.2, 0.5, 1, 3, and 5%) in eco-friendly process to produce hydrophobic CMC–C18@MWCNTs, which was then used as a sorbent material for fat content in fatty food samples analysis. The hydrophobic biopolymers were synthesized using an ultrasound-assisted esterification process, and the physicochemical properties were analyzed using FT-IR, XRD, TGA, FE-SEM, and TEM. The performance of the hydrophobic nanocomposites was evaluated by assessing their ability to remove fat content during polycyclic aromatic hydrocarbon (PAHs) analysis in tuna samples. The results showed that CMC–C18–CNT0.2% provided the best peak shapes and highest recoveries for PAHs compounds, ranging between 74.3 and 89.7%, while CMC–C18–CNT5% had the lowest recoveries, ranging between 0 and 35%. Therefore, the lowest amount of MWCNTs was found to be the most efficient for removing fat content with providing high PAHs recovery, while increasing the MWCNTs percentage increased the hydrophobicity and removed PAHs analytes along with fat content. After the investigation, the method was validated using CMC–C18–CNT0.2% in three various levels: 2, 5 and 10 μg kg−1. The obtained results were satisfactory; the average recoveries for all PAHs compounds ranged between 74.3 to 89.7%, and the intra-day precision were estimated by coefficient of variation (%CV), where were less than 10% for all PAHs. The LOD and LOQ were lies between 0.33 to 0.89 μg kg−1 and 1.12 to 1.92 μg kg−1 respectively. For the calibration curve linearity, the correlation coefficient (r2) were higher than 0.999 for all PAHs. Overall, the hydrophobic CMC–C18@MWCNTs are a promising, modifiable, and useful material for fatty food analysis.

Highly efficient hydrophobic nanocomposite in the decontamination of micropollutants and bacteria from aqueous wastes: A sustainable approach

Micro-pollutants (specifically antibiotics and personal care products) and potential bacterial contamination pose a severe threat to human health and marine life. The study derives indigenous novel fibrous hydrophobic nanocomposite, efficient in decontaminating the micro-pollutants (tetracycline (TC) and bisphenol A (BPA)) and potential pathogens (S. pyogenes and E. coli) from aqueous wastes. A facile method synthesizes the fibrous attapulgite (ATP)- poly(4-vinylpyridine-co-styrene) (PVP) framework decorated in situ with the Ag0 nanoparticles (ATP@PVP/Ag0). A greener method using the Artocarpus heterophyllus leaf extract derives the Ag0(NPs). Various analytical methods extensively characterize the materials. A comprehensive study that includes pH, concentration, background electrolytes, and ionic strength reveals the sorptive removal insights of TC and BPA utilizing the ATP@PVP solid. The elimination of tetracycline (TC) and bisphenol A (BPA) agrees well with the pseudo-second-order kinetics. The pH 3.07 and 6.06 favor removing TC and BPA with the capacity of 10.86 mg/g and 17.36 mg/g at 25 °C. The hydrogen bonding and hydrophobic interactions predominate the sorption mechanism, and the material shows remarkable stability and reusability in repeated sorption/desorption operations. Similarly, the natural water implications and flow-bed system show fair applicability of solid in decontaminating the TC and BPA in an aqueous medium. Further, the material ATP@PVP/Ag0 exhibits very high inhibition of potential pathogens S. pyogenes and E. coli and optimizes the solid dose and solution pH.

Preparation of the graphene-based smart hydrophobic nanocomposite and its application in oil/water separation.

Designing and synthesizing materials with smart hydrophobicity against an external magnetic field for efficient oil/water separation is of great importance due to the increasing problems caused by oil pollution. Here,the nanocomposites were fabricatedbased on graphene and different iron oxides exhibit smart hydrophobicity against an external magnetic fieldand they arein powder form eliminating the requirementfor a substrate employing a facile and echofriendly method. The results prove that autoclaving of graphene leads to its ferromagnetic property; then it is attached to iron oxides by magnetic attraction and a nanocomposite is produced. The magnetic property of the resulting nanocomposite is higher than the magnetic property of its individual components. In addition, following nanocomposite formation, its hydrophobicity and surface area also change. FESEM images were taken from the nanocomposites to study their surface morphology, and EDS-MAP analysis to observe the elemental distribution uniformity of the nanocomposites. Also, to measure the surface area and pore size, BET analysis has been performed on pure materials and graphene-black iron oxide nanocomposite (graphene@black iron oxide). The results show that the specific surface area of black iron oxide increases after being composited with graphene dispersed at 5000rpm. Indeed, graphene forms a composite by binding to iron oxide, and therefore, its specific surface area increases compared to iron oxide and graphene alone. These results show an increase in oil sorption and better separation of oil from water by the prepared nanocomposite. Also, to measure the magnetic properties of pure materials, graphene@black iron oxide, and ferromagnetic graphene at 3000 and 5000rpm, the Vibrating Sample Magnetometeranalysis has been performed. The results have proven that the nanocomposite powder prepared by a simple method obtained from cost-effective and available materials is hydrophobic and becomes more hydrophobic by applying an external magnetic field. Due to the ease with which oil can be readily removed from the nanocomposite by eliminating the external magnetic field, this nanocomposite is an excellent choice for the separation of oil from water.

Design of hydrophobic polyurethane–magnetite iron oxide-titanium dioxide nanocomposites for oil-water separation

Efficacious oil-water separation has become a global challenge owing to regular oil spillage accidents and escalating industrial oily wastewater. In this study, we synthesized titanium dioxide and magnetite iron oxide nanoparticles to use as a precursor for the production of the nanocomposites. Hydrophobic nanocomposites were fabricated using polyurethane, hematite and magnetite iron oxide nanoparticles, and titanium dioxide nanoparticles through a sol-gel process. The formation of the obtained nanocomposites was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. In addition, the thermogravimetric and differential thermogravimetric (TGA/DTG) and BET surface area results exhibited enhanced thermal stability of the optimized nanocomposite which displayed mesoporous type materials feature with high porosity. Furthermore, the obtained outcomes demonstrated that the distribution of nanoparticles into a polymer matrix had a significant impact on enhancing superhydrophobicity and the separation efficiency against sunflower oil. Seeing the water contact angle of the nanocomposite-coated filter paper was about 157° compared to 0° for the uncoated filter paper and endowed separation efficiency of almost 90% for 5 consecutive cycles. Thereby, these nanocomposites could be an ideal candidate for self-cleaning surfaces and oil-polluted water purification.

Preparation of RGO/Fe3O4 Nanocomposites as a Microwave Absorbing Material

The hydrophobic nanocomposites of reduced graphene oxide (RGO) and Fe3O4 (RGO/Fe3O4) were prepared by a one-pot process through co-precipitation under alkaline conditions. The microwave absorption performance of the RGO/Fe3O4 nanocomposites was analyzed according to their electromagnetic parameters. The results showed that the RGO/Fe3O4 nanocomposites displayed better absorbing performance than the pristine Fe3O4 nanoparticles, owing to the synergistic effect of Fe3O4 and RGO. The maximum reflection loss (RL) of the RGO/Fe3O4 nanocomposites with a thickness of 2 mm reached −45.7 dB at 13.3 GHz, and the bandwidth (RL < −10 dB) ranged from 11.5 to 16.5 GHz. However, the maximum RL of the Fe3O4 nanoparticles with a thickness of 5 mm only reached −5.3 dB at 5.7 GHz. The RGO/Fe3O4 nanocomposites have a great potential application in high-performance electromagnetic microwave absorbing.

Design of Sol–Gel Hybrid Bio-sourced Lignin/Silica Hydrophobic Nanocomposites through a Dip-Coated Evaporation-Induced Self-Assembly Method

Design of Sol–Gel Hybrid Bio-sourced Lignin/Silica Hydrophobic Nanocomposites through a Dip-Coated Evaporation-Induced Self-Assembly Method

TEOS-PDMS-Calcium Oxalate Hydrophobic Nanocomposite for Protection and Stone Consolidation

A treatment for both protection and consolidation, was synthesized in a simplified procedure through the sol gel process. Synthesized nano-calcium oxalate (CaOx) was incorporated into tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS), providing a hybrid hydrophobic consolidant nanocomposite. Oxalic acid was selected due to its ability to catalyse the hydrolysis of TEOS, as a drying control agent, but also because of its contribution at the formation of the calcium oxalate in reaction with calcium hydroxide. CaOx, incorporated into the silica matrix of the final copolymer, exhibits interfacial compatibility with the stone substrate and simultaneously strengthens the treated surface, since CaOx appears to be more stable than calcium carbonate. The hydrolysis of TEOS, as well as the formation of CaOx was evaluated through thermogravimetric analysis (TG/DTA). The nanocomposite consists of particles with approximately 7–700 nm in size range, as shown in TEM images. The consolidation, in combination with the hydrophobicity of surface resulted in an increase of the resistance to decay. Mechanical properties were enhanced as evaluated by ultrasonic pulse velocity on treated and untreated surfaces. Furthermore, water contact angle, as well as water absorption by capillarity test, showed improved water repellency of treated stones. Finally, this treatment doesn’t alter the aesthetic surface parameters, a fact that is essential in cultural heritage conservation, while the consolidant remains intact under UV and moisture exposure.

Reducing failure in power transition lines using a novel nano silica/silicone rubber hydrophobic coating of glass insulator

Flashover failure is a significant issue that reduces the ability to insulate the glass insulators in power transition lines. The main reason is the surface contaminates, which increases the conductivity of the surface leading to flashover occurrence. A sol-gel method was used to create a hydrophobic surface on the high voltage glass insulator, preventing dusty or salty water droplets from adhering to its surface. The cold spraying technique was utilized to build up a thin nanocomposite hydrophobic layer on the glass insulator containing different percentages of nanosilica particles, such as 23%, 33%, and 44% with the potting compound silicone substrate. The wettability test, hardness, roughness and dielectric strength of the produced nanocomposite were investigated. Furthermore, the surface morphology of the prepared silicone rubber/nanosilica hydrophobic nanocomposite was occurred using the FESEM analysis. The findings show that silicone rubber/33% nanosilica exhibits the best hydrophobic behavior, with a contact angle is more than 133.3˚. Also, the change in dielectric strength was 16.4% when adding 33% percentage of the nanosilica. The flashover test was also performed, and it was discovered that the leak current between the coated and uncoated samples were differed significantly. Using a 60 kV voltage load, the leak current of the coated sample with a hydrophobic nanocomposite was decreased to 2.4 mA, whereas the untreated sample was 3.1 mA. These findings may assist to enhance the hybrid nanocomposite as hydrophobic surface made of silica nanoparticles/silicone base preventing contaminants from adhering on the insulating glass in high voltage power transition lines.

Ag-TiO2/PDMS nanocomposite protective coatings: Synthesis, characterization, and use as a self-cleaning and antimicrobial agent

The protection of our artifacts becomes a necessity due to several decay phenomena induced by pollution, microorganism colonization, and water. This research study has been focused on elaborating photo-activated nanocomposites to protect outdoors heritage buildings. Hence, novel Ag-TiO2/PDMS hydrophobic nanocomposites (with low doping rates) thin films with enhanced photo-response activity have been developed to be used as self-cleaning durable protective coatings in the field of monument conservation. The protective coatings elaborated in this work are intended to have multifunctional properties (water repellent features, self-cleaning activity, antimicrobial agent). To reach our objective, silver-doped titanium dioxide nanoparticles (Ag-TiO2 NPs) at different doping amounts (0.1, 1, 3, and 5 mol%) were firstly synthesized by the sol-gel method. As-prepared NPs were characterized and their performance was evaluated comparatively to find out the appropriate low doping rates of the dopant by testing photo-degradation as well as photo-killing activities. The second part of this research is focused on elaborating Ag-TiO2/PDMS hydrophobic nanocomposites (selected low doping rates) as self-cleaning protective coatings. For this purpose, Ag-doped TiO2 NPs were dispersed in a polymeric binder (polydimethylsiloxane, PDMS) and applied to the very porous stone substrate, i.e., Lecce stone (LS). The suitability of the resulting nanocomposites (optimal Ag doped TiO2 NPs/ binder ratio; optimal doping amount) on the stone substrate was evaluated by performing different experimental analyses: chromatic measurements, contact angle measurements, water capillary absorption test, permeability to water vapour, pencil and Vickers hardness tests, optical microscope analyses, and scanning electron microscopic analyses combined with energy-dispersive X-ray spectroscopy (SEM-EDS), microbiological experiments, and self-cleaning test. Moreover, the durability of the nanocomposite coatings was also assessed after exposing to different ageing cycles. Results suggested that the samples doped with low concentrations (≤1 mol%) of silver (Ag-doped TiO2) together with PDMS can be considered as efficient and durable protective coatings for the highly porous bio-calcarenite stone. Such doping amount is considered very low compared to the other research works that have been performed in the same field.

The effect Ecofriendly Super hydrophobic Nano composites Coating and Penetration of Printing Inks on Paperboard Packaging Materials

The packaging industry is one of the pioneering industries facing many challenges during the production cycle. Migration of printing ink in packing items is the harmful problem for customer, Therefore, this study aims to reduce the penetration of ink into the product, one of the unavailable technologies is coating printing substrates with a polymer layer. Ecofriendly Super hydrophobic coating was prepared in aqueous medium based on silicon dioxide and characterized with particle size analyzer Dynamic laser scattering )DLS( and zeta potential. Paper duplex 180 g/m2 were coated with prepared superhydrophobic Nano coating through spray coating with emulsion solution. The coated paper sheets were printed by lithooffist and testes by X-rite instrument. This polymer can seal the pores of the printing materials. It is also a barrier to prevent the leakage and deportation of ink particles into the packaging that can occur in various raw materials, especially untreated materials as well as. One of the advantages of this polymer is to reduce the penetration of ink consumed for printing, that is, it is of double benefit, which is protection and reduce ink penetration, and the research results show the effective use of this polymer layer, whether in roughness, water absorption, Ink penetration and printing properties

Hydrophobic nanocomposites of PBAT with Cl‐fn‐POSS nanofiller as compostable food packaging films

AbstractAntibacterial nanocomposite films of poly(butylene adipate‐co‐terephthalate) (PBAT) incorporated with different weight percentage of octakis(3‐chloropropyl)octasilsesquioxane (chloropropyl functionalized POSS [Cl‐fn‐POSS]) nanofiller were prepared. The mechanical, thermal, morphological, barrier, and antimicrobial properties were examined. The mechanical properties of the nanocomposite films were enhanced by the addition of Cl‐fn‐POSS nanofiller. An optimum filler loading of 3 wt% is identified to be best suited for maximum enhancement in tensile strength (24 MPa for 3 wt% filled PBAT vs 11 MPa for neat PBAT) while a 1 wt% filler loading was adequate to double the tensile strength. The barrier properties (WVTR and oxygen transmission rate) of PBAT was improved by the presence of Cl‐fn‐POSS. A volume of 3 wt% filler loading results in 50% reduction of water permeation and 10% reduction in oxygen transmission. The thermogravimetric analyses of the nanocomposites indicated that the filler enabled the enhancement of thermal stability of PBAT. The nanocomposite films revealed antimicrobial activity with this activity increasing with increasing filler content. PBAT is compostable under suitable conditions and with a low weight percentage of filler that is largely made of silicon dioxide these nanocomposite films can find application as biodegradable food packaging material given their flexibility.

Congo Red Decolorization Using Textile Filters and Laccase-Based Nanocomposites in Continuous Flow Bioreactors.

Removal of azo and diazo dye content from textile industry wastewaters is crucial due to their environmental impact. Here, we report on the use of the fungal laccase from Pycnoporus sanguineus CS43 immobilized on silica nanoparticles and entrapped in textile-based filters for the degradation of Congo Red. Laccase immobilization and synthesis of the nanocomposites were carried out by two different methods, one in the presence of acetone and the second using water as solvent. This led to a change in the hydrophobicity of the obtained biofilters. Successful preparation of the nanocomposites was confirmed via FTIR spectroscopy. Changes in the secondary structure of the enzyme were inspected through the second derivative of the FTIR spectra. Six different types of filter were fabricated and tested in a continuous flow bioreactor in terms of their decolorization capabilities of Congo Red. The results indicate removal efficiencies that approached 40% for enzymes immobilized on the more hydrophobic supports. Backscattered electron (BSE) images of the different filters were obtained before and after the decolorization process. Percentage of decolorization and activity loss were determined as a function of time until a plateau in decolorization activity was reached. Experimental data was used to recreate the decolorization process in COMSOL Multiphysics® (Stockholm, Sweden). These simulations were used to determine the proper combination of parameters to maximize decolorization. Our findings suggest that the treatment of textile-based filters with immobilized laccase in conjunction with hydrophobic nanocomposites provides a suitable avenue to achieve more efficient laccase dye decolorization (39%) than that obtained with similar filters treated only with free laccase (8%). Filters treated with silica-based nanocomposites and immobilized laccases showed an increase in their decolorization capability, probably due to changes in their wetting phenomena.

White Graphene-Cobalt Oxide Hybrid Filler Reinforced Polystyrene Nanofibers for Selective Oil Absorption.

In this work, stable hydrophobic nanocomposites are made from electrospun fibers of polystyrene (PS) containing a hybrid filler combination of (i) hexagonal boron nitride (hBN) and (ii) cobalt oxide (Co3O4) nanomaterials. Good synergistic interaction is observed between the nanomaterials, since the growth of Co3O4 was carried out in presence of white graphene nanosheets. Filler synergy modifies the PS surfaces, by enhancing the filler-polymer interfacial interactions and provides good tensile strength. The hydrophobic films are gamma irradiated to improve crosslinking within the polymer nanocomposites. Since gamma irradiation enhances the surface roughness, its hydrophobicity/oleophilicity increases much and the final nanofibers show good oil-water separation efficiency. The nanofibers act as sponge clothing to skim the oil from a mixture of oil and water. Durability of the fibers in hot water and in presence of ultrasonic waves is also tested and good response is achieved. Contact angle studies are performed to investigate the surface properties and to check the influence of gamma irradiation on the surface wettability. The gamma-irradiated PS nanocomposite fiber shows a contact angle of 152° ± 2° compared to the 140° ± 1° of the neat PS fiber, evidencing the superhydrophobicity. Both the effects of crosslink density enhancement and hybrid filler distribution make the composite fibers stronger in oil absorption application even at higher operation temperatures. The fibers are reported to be robust and durable, in addition.

Weathering Effect on Surface Characteristics of Superhydrophobic/ Hydrophobic Nanocomposites Coating

Weathering Effect on Surface Characteristics of Superhydrophobic/ Hydrophobic Nanocomposites Coating

Rheological properties and anticorrosion performance of graphene oxide- and reduced graphene oxide-based nanocomposites

In this study, the effect of graphene oxide (GO) and reduced graphene oxide (rGO) nanoparticles on the corrosion protection performance of nanocomposite coatings containing particle mass concentration ranging from 0.25% to 1% in epoxy matrix was investigated in detail. In addition, the effect of the distribution of GO and rGO nanoparticles in epoxy matrix on the corrosion performance and rheology of the coatings was studied by mixing the nanocomposites with the ball milling for 24 and 48 h. The surface morphology of coatings was analyzed by field-emission scanning microscope. It was observed that oxygen groups in the graphene structure, the effective distribution of nanoparticles in the matrix and the amount of nanoparticle doped affected the corrosion protection performance. The best corrosion protection performance among all nanocomposite coatings was 0.75 wt% rGO/epoxy nanocomposite, which was milled for 48 h. GO/epoxy nanocomposite coatings exhibit hydrophilic properties in all mass fractions and mixing times. However, adding 0.5 and 0.75 wt% of rGO and milling 48 h resulted in hydrophobic nanocomposites. rGO nanoparticles had the best dispersion performance at 0.75 wt% concentration in the epoxy. The nonlinear rheological measurements revealed that rGO/epoxy nanocomposites exhibit non-Newtonian shear thinning behavior at the studied mass concentrations and milling times as opposed to the nanocomposites containing GO particles.

Poly(glycidyl methacrylate)/bacterial cellulose nanocomposites: Preparation, characterization and post-modification.

Nanocomposites composed of poly(glycidyl methacrylate) (PGMA) and bacterial cellulose (BC) were prepared by the in-situ free radical polymerization of glycidyl methacrylate (GMA) inside the BC network. The resulting nanocomposites were characterized in terms of structure, morphology, water-uptake capacity, thermal stability and viscoelastic properties. The three-dimensional structure of BC endowed the nanocomposites with good thermal stability (up to 270 °C) and viscoelastic properties (minimum storage modulus = 80 MPa at 200 °C). In addition, the water-uptake and crystallinity decreased with the increasing content of the hydrophobic and amorphous PGMA matrix. These nanocomposites were then submitted to post-modification via acid-catalysed hydrolysis to convert the hydrophobic PGMA into the hydrophilic poly(glyceryl methacrylate) (PGOHMA) counterpart, which increased the hydrophilicity of the nanocomposites and consequently improved their water-uptake capacity. Besides, the post-modified nanocomposites maintained a good thermal stability (up to 250 °C), viscoelastic properties (minimum storage modulus = 171 MPa at 200 °C) and porous structure. In view of these results, the PGMA/BC nanocomposites can be used as functional hydrophobic nanocomposites for post-modification reactions, whereas the PGOHMA/BC nanocomposites might have potential for biomedical applications requiring hydrophilic, swellable and biocompatible materials.

Preparation and properties of super hydrophobic films from siloxane-modified two-component waterborne polyurethane and hydrophobic nano SiO2

Nanocomposite films with super hydrophobic surface were prepared by building rough micro/nano structure on the surface of siloxane-modified two-component waterborne polyurethane (2K-WPU) with hydrophobic nano SiO2. Firstly, nano SiO2 prepared by StÖber method with tetraethoxysilane (TEOS) as precursor was modified with trimethylethoxysilane (TMES), in order to cover a layer of hydrophobic methyl groups on the surface of nano SiO2. Then, a series of nanocomposite films with different water contact angles were obtained by adding different contents of TMES modified SiO2 into the siloxane-modified 2K-WPU. The effects of the content of nano SiO2 on the morphology and hydrophobicity of film surface were investigated. The results showed that the surface structures of the nanocomposite films became rougher and the water contact angle of nanocomposite films was increased obviously with the increase of the content of hydrophobic nano SiO2. Super hydrophobic nanocomposite film with water contact angle over 150° was successfully fabricated by using polysiloxane as low surface energy material and hydrophobic nano SiO2 as micro/nano rough structure builder on the polymer surface. Moreover, incorporating nano SiO2 into the 2K-WPU matrix could increase the glass transition temperature and thermal stability of the nanocomposite films.

Surface-initiated atom transfer radical polymerization grafting from nanoporous cellulose gels to create hydrophobic nanocomposites.

Here, we present the preparation of hydrophobic nanoporous cellulose gel-g-poly(glycidyl methacrylate) (NCG-g-PGMA) nanocomposites by surface-initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) monomers and hydrophobic modification with pentadecafluorooctanoyl chloride (C7F15COCl) on the cellulose nanofibrils of the NCG. The successful grafting of PGMA and hydrophobic modification of C7F15CO– groups on the NCG was evaluated by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed that the SI-ATRP and hydrophobic modification did not change the microscopic morphology and structure of the NCG-g-PGMA nanocomposites. Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) showed remarkable thermomechanical properties and moderate thermal stability. The method has tremendous promise to use NCG as a platform for SI-ATRP and produce new functional NCG-based nanomaterials.

Superior thermomechanical and wetting properties of ultrasonic dual mode mixing assisted epoxy-CNT nanocomposites

High-performance epoxy-carbon nanotube (CNT) nanocomposites were prepared by simultaneous use of ultrasonication and mechanical stirring. The dynamic and static mechanical properties and wetting properties of the nanocomposites were investigated. The dynamic mechanical analysis presented significant enhancement in storage modulus (approximately 124%) and glass transition temperature (approximately 25.6%) of epoxy-CNT nanocomposite at an optimized concentration of the CNT (0.25 wt%) possibly due to the formation of a strong interface between the epoxy and CNT. The tensile test results showed the significant improvement in tensile strength (approximately 47%) and Young’s modulus (approximately 40%) of the epoxy-CNT (0.25 wt%) nanocomposite without significantly affecting its stiffness. The homogeneous dispersion of CNTs in the epoxy matrix resulted in the significant enhancement in the dynamic and static mechanical properties of the nanocomposites. The hydrophilic character of the neat epoxy was tuned to a highly hydrophobic one by incorporation of CNTs in it. A direct relation between the average roughness of the tensile fracture surfaces and the contact angle of the nanocomposites was identified with respect to the concentration of the CNTs. These high-performance highly hydrophobic nanocomposites have the great potential to be used as the structural and functional materials in humid environments.

Enhanced viscoelastic property of iron oxide nanoparticle decorated organoclay fluid under magnetic field

Stable hydrophobic nanocomposites of magnetic nanoparticles and clay are prepared by the self-assembly of magnetite (Fe3O4) nanoparticles on surfaces of exfoliated clay platelets. Due to the attractive interaction between hydrophobic groups, oleic acid coated nanoparticles are strongly attached to the surface of cetyl trimethylammonium cation coated clay platelets in organic media. Crystal structure and magnetic property of composite particles are examined using electron microscopy, x-ray diffractometer and vibration sample magnetometer. In addition, composite particles are dispersed in mineral oil and rheological properties of composite particle suspensions are characterized using steady-state and oscillatory measurements. Magnetite nanoparticle decorated organoclay forms a tunable network in mineral oil. When a magnetic field is applied, the composite particle fluid exhibits higher storage modulus and maintains a solid-like property at larger strain. Our results show that the viscoelastic property of the magnetite nanoparticle decorated organoclay fluid is controlled by applying external magnetic field.