Search for: hydrophobicity
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    Effect of water-methanol content on the structure of Nafion in the sandwich model and solvent dynamics in nano-channels; A molecular dynamics study

    , Article Molecular Physics ; Volume 109, Issue 5 , Mar , 2011 , Pages 709-724 ; 00268976 (ISSN) Abroshan, H ; Akbarzadeh, H ; Taherkhani, F ; Parsafar, G ; Sharif University of Technology
    Continuing an ongoing study, molecular dynamics (MD) simulations were performed to investigate the effects of methanol concentration on Nafion morphology, such as the size of solvent cluster, solvent location, and polymer structure via the sandwich model. Our survey shows that high methanol concentrations resulted in increment of solvent cluster size in Nafion membrane. The sulfonic acid clusters also befall much in order as subsequent layers of such ionic clusters are formed. The number of neighbouring hydronium ions around a sulfur atom is independent of methanol concentration, but the first shell of hydronium and water around sulfonic acid clusters is broader. Although methanol would... 

    Paclitaxel/β-CD-g-PG inclusion complex: An insight into complexation thermodynamics and guest solubility

    , Article Journal of Molecular Liquids ; Volume 208 , August , 2015 , Pages 145-150 ; 01677322 (ISSN) Zarrabi, A ; Vossoughi, M ; Sharif University of Technology
    Elsevier  2015
    Paclitaxel as one of the most effective anticancer drugs has low aqueous solubility. This inevitably reveals its commercial formulation in Cremophor EL®/ethanol mixture. However, this formulation leads to several severe side effects such as hypersensitivity reactions, neurotoxicity and nephrotoxicity. Inclusion complexation has been introduced as a practical approach in increasing paclitaxel aqueous solubility. To this end, a hybrid nanocarrier system based on hyperbranched polyglycerol and β-cyclodextrin is designed with key components uniquely structured at nanoscale and evaluated according to medical requirements. Paclitaxel is included in the hydrophobic cavity of cyclodextrin as guest... 

    Investigation of salts behavior at liquid–liquid interfaces

    , Article Springer Proceedings in Mathematics and Statistics, 26 August 2013 through 30 August 2013 ; Volume 117 , July , 2015 , Pages 265-270 ; 21941009 (ISSN) ; 9783319123066 (ISBN); 9783319123066 (ISBN) Khiabani, N. P ; Bahramian, A ; Soltani, M ; Pourafshary, P ; Sarikhani, K ; Chen, P ; Ejtehadi, M. R ; Makarov R. N ; Melnik R. V. N ; Kotsireas I. S ; Shodiev H ; Cojocaru M. G ; Cojocaru M. G ; Makarov R. N ; Melnik R. V. N ; Kotsireas I. S ; Shodiev H ; Sharif University of Technology
    Springer New York LLC  2015
    We have used molecular dynamics simulation to investigate hydrophilic– hydrophobic interfaces between calcium chloride (CaCl2) aqueous solutions and normal hexane. The results demonstrate the increasing impact of salt concentration on the liquid–liquid interfacial tension, hence, negative adsorption of CaCl2 according to Gibbs adsorption isotherm. Moreover, we calculated the density profiles of hexane, water, and the counter ions. The results reveal an electrical double layer near the interface and the less affinity of calcium cations toward the interface than that of chloride anions. Orientation of water molecules at the studied concentrations may result in developing a positively charged... 

    Droplet condensation on chemically homogeneous and heterogeneous surfaces

    , Article Journal of Applied Physics ; Volume 120, Issue 12 , 2016 ; 00218979 (ISSN) Ashrafi, A ; Moosavi, A ; Sharif University of Technology
    American Institute of Physics Inc  2016
    Nucleation and growth of condensing droplets on horizontal surfaces are investigated via a 2-D double distribution function thermal lattice Boltzmann method. First, condensation on completely uniform surface is investigated and different mechanisms which cause dropwise and filmwise condensation are studied. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. In the second step, condensation on chemically heterogeneous surfaces is investigated. Moreover, the effect of non-uniformity in the surface temperature is also studied. The results indicate that the vapor layer instability and the nucleation start from the heterogeneities.... 

    Preparation of new superhydrophobic and highly oleophobic polyurethane coating with enhanced mechanical durability

    , Article Applied Surface Science ; Volume 454 , 2018 , Pages 201-209 ; 01694332 (ISSN) Yousefi, E ; Ghadimi, M. R ; Amirpoor, S ; Dolati, A ; Sharif University of Technology
    In this study, a noble robust superhydrophobic and highly oleophobic polyurethane (PU)–SiO2 nanoparticle (NP) coating is specially designed using sol-gel process. For this purpose the effective parameters on surface tension and durability of the synthesized coating investigated and optimized. This new superhydrophobic and highly oleophobic coating exhibits good pensile hardness as high as 6H with adhesive force grade of 5B and repels water and oil with contact angles (CAs) of 159° and 140° respectively. The synthesized PU-SiO2 composite also retains an excellent amphiphobicity after a 7 days immersion in water with water and oil with CAs of 150° and 130°. Facile fabrication of PU–SiO2... 

    Bare and functionalized nanodiamonds in aqueous media: a theoretical study

    , Article Diamond and Related Materials ; Volume 89 , 2018 , Pages 301-311 ; 09259635 (ISSN) Aranifard, S ; Shojaei, A ; Sharif University of Technology
    Nanodiamond particles, basically those produced by detonation method, are acquiring progressive attraction in different fields such as material, biomedical, and environmental engineering. Aqueous environments are usually dealt with at different stages of preparation, preservation, and application of these particles. The aim of this article is to perform a systematic first-principles density functional theory analysis on the interaction of C35 ultrasmall octahedral nanodiamond and its full homogeneous carboxylated and aminated forms, with water derived specie, namely, neutral, protonated, and deprotonated water and (H2O)20 water cluster. The effect of solvent media on the interactions has... 

    A nanopaper-based artificial tongue: a ratiometric fluorescent sensor array on bacterial nanocellulose for chemical discrimination applications

    , Article Nanoscale ; Volume 10, Issue 5 , February , 2018 , Pages 2492-2502 ; 20403364 (ISSN) Abbasi Moayed, S ; Golmohammadi, H ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2018
    In the present study, a ratiometric fluorescent sensor array as an artificial tongue has been developed on a nanopaper platform for chemical discrimination applications. The bacterial cellulose (BC) nanopaper was utilized for the first time as a novel, flexible, and transparent substrate in the optical sensor arrays for developing high-performance artificial tongues. To fabricate this platform, the hydrophobic walls on the BC nanopaper substrates were successfully created using a laser printing technology. In addition, we have used the interesting photoluminescence (PL) properties of an immobilized ratiometric probe (carbon dot-Rhodamine B (CD-RhB) nanohybrids) on the nanopaper platform to... 

    A new approach for preparation of semi-transparent superhydrophobic coatings by ultrasonic spray hydrolysis of methyltrimethoxysilane

    , Article Progress in Organic Coatings ; Volume 135 , 2019 , Pages 248-254 ; 03009440 (ISSN) Rahemi Ardekani, S ; Sabour Rouh Aghdam, A ; Nazari, M ; Bayat, A ; Saievar Iranizad, E ; Sharif University of Technology
    Elsevier B.V  2019
    A novel nebulizing spray hydrolysis approach was used for preparation of semi-transparent superhydrophobic coatings. Methyltrimethoxysilane was dissolved in water:ethanol mixture and ultrasonically sprayed on different substrates. Superhydrophobic coatings with a contact angle (CA) as high as 164° and a sliding angle below 5° were obtained. FESEM and AFM revealed a hierarchical micro-nano binary structure with nanometric roughness of the coatings. The coated glass substrate exhibited transmittance close to 80%. The prepared coating showed great self-cleaning and water jet repellency behaviors. The superhydrophobicity of the samples was remained after subjecting to ambient conditions for 50... 

    A comprehensive review on recent advances in superhydrophobic surfaces and their applications for drag reduction

    , Article Progress in Organic Coatings ; Volume 140 , March , 2020 Liravi, M ; Pakzad, H ; Moosavi, A ; Nouri Borujerdi, A ; Sharif University of Technology
    Elsevier B. V  2020
    Nowadays, superhydrophobic surfaces have attracted a lot of interest because of the wide range of applications in industries. These surfaces can significantly reduce the drag force due to the formation of air gaps between the substrate and liquid interface. The present review mainly focuses on the very recent progresses in the drag reduction studies using superhydrophobic surfaces. Also, a brief discussion about the mathematical modeling and the theories of superhydrophobic surfaces, natural water repellent surfaces, various fabrication techniques with advantages and disadvantages of each method and different properties of the fabricated surfaces in industrial applications is presented.... 

    Theoretical and experimental study of foam stability mechanism by nanoparticles: Interfacial, bulk, and porous media behavior

    , Article Journal of Molecular Liquids ; Volume 304 , 2020 Suleymani, M ; Ghotbi, C ; Ashoori, S ; Moghadasi, J ; Kharrat, R ; Sharif University of Technology
    Elsevier B.V  2020
    Foam flooding has been applied as a promising method in enhanced oil recovery to obviate the challenges of gas flooding such as fingering, channeling and overriding. However, long-term foam stability is crucial for mobility control. In this work, the effective mechanisms on foam stability in the presence of CaCO3 nanoparticles were assessed both theoretically and experimentally. The static and dynamic behaviors of cationic surfactant (HTAB) foam in the presence of CaCO3 nanoparticles with different hydrophobicity were evaluated. The CaCO3 nanoparticles were treated with a series of long-chain fatty acids to generate a range of wettability. Afterward, the underlying mechanisms were revealed... 

    Carrageenan-Based functional films integrated with cuo-doped titanium nanotubes for active food-packaging applications

    , Article ACS Sustainable Chemistry and Engineering ; Volume 9, Issue 28 , 2021 , Pages 9300-9307 ; 21680485 (ISSN) Ezati, P ; Riahi, Z ; Rhim, J. W ; Sharif University of Technology
    American Chemical Society  2021
    A titanium dioxide nanotube (TNT) and CuO-doped TNT (TNT-CuO) were synthesized using a hydrothermal method and incorporated into carrageenan-based films. The SEM results confirmed the formation of uniform nanocomposite films. The addition of nanoparticles imparted UV-blocking properties to the carrageenan film and increased the mechanical strength, surface hydrophobicity, and water vapor barrier properties. The modified TiO2 (TNT and TNT-CuO)-incorporated carrageenan films showed significantly higher antibacterial activity than the TiO2-added film under visible light. Bananas packaged with the neat carrageenan and TiO2-added films were degraded considerably after 12 days of storage at 20 °C.... 

    Step-by-step improvement of mixed-matrix nanofiber membrane with functionalized graphene oxide for desalination via air-gap membrane distillation

    , Article Separation and Purification Technology ; Volume 256 , 2021 ; 13835866 (ISSN) Fouladivanda, M ; Karimi Sabet, J ; Abbasi, F ; Moosavian, M. A ; Sharif University of Technology
    Elsevier B.V  2021
    A straightforward three-stage method was applied to fabricate a super-hydrophobic mixed-matrix nanofiber membrane using the electrospinning method for desalination purpose. First, a hydrothermal technique was applied to synthesize a super-hydrophobic nano-sheet, called octadecylamine-reduced graphene oxide (ODA-rGO) with a water contact angle of 162°, which was then added to PVDF-HFP dope solution. After, 0.005 wt% LiCl was added to the dope solution to decrease the mean pore size by increasing solution conductivity. Moreover, some membranes were hot-pressed to improve liquid entry pressure (LEP). Eventually, a top-quality nanofiber membrane was synthesized using 0.1 wt% ODA-rGO and 0.005... 

    Superhydrophobic home-made polyurethane sponges for versatile and cost-effective oil and water separation

    , Article Separation and Purification Technology ; Volume 276 , 2021 ; 13835866 (ISSN) Jabbary Farrokhi, S ; Pakzad, H ; Fakhri, M ; Moosavi, A ; Sharif University of Technology
    Elsevier B.V  2021
    Utilizing 3D and 2D porous materials modified by a superhydrophobic/philic coating for quick removal of oil from water and a continuous process of oil/water separation, respectively, has attracted a lot of attention recently. Here we report the separation capacities of one commercial and three home-made sponges, sprayed by a superhydrophobic coating, for a broad range of oils and solvents. The contact angle of water on the coated sponges is 162.5˚, whereas the pristine sponge shows a contact angle of 91.8˚ (these values are for sponge D which had the highest absorption capacity). We investigate the effects of the density of sponges and the dynamic viscosity of oils and solvents on the... 

    Friction reduction in a nanochannel with grafted poly(N-isopropylacrylamide) oligomers: A molecular dynamics study

    , Article Physics of Fluids ; Volume 33, Issue 5 , 2021 ; 10706631 (ISSN) Saleki, O ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
    American Institute of Physics Inc  2021
    Superhydrophobic surfaces have been used for reducing friction in micro- and nanochannels. In the present work, water flow between two carbon walls with nanostructures made of poly(N-isopropylacrylamide) via the molecular dynamics method has been studied. The structure of this polymer can change based on the temperature of the environment, so that by increasing the temperature the structure becomes hydrophobic. This property has been studied and the effect of multiple factors on the slip length is presented. The effects of the number of monomers in the polymer, the distance between the polymers, and the temperature on the flow field are investigated. The results reveal that the slip length... 

    Fog harvesting: combination and comparison of different methods to maximize the collection efficiency

    , Article SN Applied Sciences ; Volume 3, Issue 4 , 2021 ; 25233971 (ISSN) Sharifvaghefi, S ; Kazerooni, H ; Sharif University of Technology
    Springer Nature  2021
    Fog harvesting is an unconventional source of water that can be used in some regions with water scarcity to overcome water shortages. The most commonly used collectors are meshes which have intrinsic limitations, the most important of which are clogging and aerodynamic deviation of droplets around the wires. Here, three techniques are compared and combined to overcome these limitations, i.e., replacing the mesh with an array of vertical wires, addition of a hydrophobic layer to the wires, and forcing the ionized droplets to move toward the wires by applying an electric field. The combination of these techniques was found to result in higher fog harvesting efficiency compared to each... 

    Mechanically stable superhydrophobic nanostructured aluminum mesh with reduced water surface friction

    , Article Nanotechnology ; Volume 32, Issue 19 , 2021 ; 09574484 (ISSN) Taghvaei, E ; Afzali, N ; Taghvaei, N ; Moosavi, A ; Sharif University of Technology
    IOP Publishing Ltd  2021
    Superhydrophobic surfaces demonstrate significant characteristics which make them suitable for a wide variety of applications. In this study, we propose a facile, one-step, and cost-effective anodizing scheme using aluminum nitrate/stearic acid mixture solution to create a superhydrophobic surface on an aluminum mesh. The surface outperforms the surface anodized by the widely used oxalic acid solution in terms of superhydrophobicity and water-surface friction behavior. The proposed surface reduced the friction by 11% on average respective to the surface prepared by oxalic acid. The durability of the introduced superhydrophobic surface has also been investigated. The proposed surface retained... 

    Superior anti-biofouling properties of mPEG-modified polyurethane networks via incorporation of a hydrophobic dangling chain

    , Article Progress in Organic Coatings ; Volume 158 , September , 2021 ; 03009440 (ISSN) Golmohammadian Tehrani, A ; Makki, H ; Ghaffarian Anbaran, R ; Vakili, H ; Ghermezcheshme, H ; Zandi, N ; Sharif University of Technology
    Elsevier B.V  2021
    PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the... 

    Lipid membranes with transmembrane proteins in shear flow

    , Article Journal of Chemical Physics ; Volume 132, Issue 2 , 2010 ; 00219606 (ISSN) Khoshnood, A ; Noguchi, H ; Gompper, G ; Sharif University of Technology
    The effects of embedded proteins on the dynamical properties of lipid bilayer membranes are studied in shear flow. Coarse-grained molecular simulations are employed, in which lipids are modeled as short polymers consisting of hydrophilic head groups and hydrophobic tail monomers; similarly, transmembrane proteins are modeled as connected hydrophobic double- or triple-chain molecules with hydrophilic groups at both ends. In thermal equilibrium, rigid proteinlike molecules aggregate in a membrane of flexible lipids, while flexible proteins do not aggregate. In shear flow parallel to the membrane, the monolayers of lipid bilayer slide over each other. The presence of transmembrane proteins... 

    Utilization of molecular dynamics simulation coupled with experimental assays to optimize biocompatibility of an electrospun PCL/PVA scaffold

    , Article PLoS ONE ; Volume 12, Issue 1 , 2017 ; 19326203 (ISSN) Sarmadi, M ; Shamloo, A ; Mohseni, M ; Sharif University of Technology
    Public Library of Science  2017
    The main focus of this study is to address the possibility of using molecular dynamics (MD) simulation, as a computational framework, coupled with experimental assays, to optimize composite structures of a particular electrospun scaffold. To this aim, first, MD simulations were performed to obtain an initial theoretical insight into the capability of heterogeneous surfaces for protein adsorption. The surfaces were composed of six different blends of PVA (polyvinyl alcohol) and PCL (polycaprolactone) with completely unlike hydrophobicity. Next, MTT assay was performed on the electrospun scaffolds made from the same percentages of polymers as in MD models to gain an understanding of the... 

    Electrospun polyethersolfone nanofibrous membrane as novel platform for protein immobilization in microfluidic systems

    , Article Journal of Biomedical Materials Research - Part B Applied Biomaterials ; Volume 106, Issue 3 , April , 2018 , Pages 1108-1120 ; 15524973 (ISSN) Mahmoudifard, M ; Vossoughi, M ; Soudi, S ; Soleimani, M ; Sharif University of Technology
    John Wiley and Sons Inc  2018
    In the present study, the feasibility of electrospun polyethersolfone (PES) nanofibrous membrane as the solid substrate for microfluidic based immunoassays to enhance the density of immobilized antibody on the surface of membrane was assessed. Conversely, the efficacy of antibody immobilization was compared by two different strategies as 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) coupling chemistry and hydrophobic interaction. Compared to conventional immunoassays carried out in plates or gels, microfluidic based immunoassays grant a lot of advantages such as a consumption of little samples and reagents, shorter analysis time, and higher efficiency....