Sharif Digital Repository

The current study deals with application of a surfactant-like Brønsted acidic ionic liquid (IL) 1-dodecyl-3-methylimidazolium hydrogensulfate (catalys 1) for Mannich reaction at room temperature. The reaction has been efficiently proceeds in water as solvent without using any harmful and expensive organic additives. Our observation has been shown that the reaction is selective for cyclohexanone and no product was observed by using cyclopentanone at room temperature. Density functional theory (DFT) calculations were performed to provide evidence about the nature of reactivity of the cyclohexanone/cyclopentanone. The activity of the catalyst 2 (1-dodecyl-2,3-dimethylimidazolium... 

Considering the importance of environmental issues and the limitation of fuel supplies in the world, car issues have become one of the most important debates of the day. The methods used to reduce fuel consumption and emissions of greenhouse gases are primarily aimed at changing vehicle structure to reduce drag. An external body shape has been developed to reduce drag forces over the years. Due to the existence of limitations in the actual conditions of the theory, such as the beauty and convenience production, other methods should be examined. In this study, the structure of superhydrophobic properties materials with the emphasis on innovation has been considered. In order to investigate... 

This project aims to study corrosion protection performance of silane coating based on tetraethylorthosilicate (TEOS), (3-Mercaptopropyl) trimethoxysilane (MPTS) and Hexamethyldisilazane (HMDS) on carbon steel substrate. Water contact angle (WCA) were measured to study hydrophobicity. The water contact angle increased from 60 degrees in carbon steel to 134.8 degrees in the sample containing 0.35 MPTS and 1.25 HMDS. Surface morphology was studied using Field emission scanning electron microscopy (FESEM) and chemical analysis was conducted using Fourier Transform Infrared Spectroscopy (FTIR). Corrosion resistance was studied by means of Electrochemical Impedance Spectroscopy (EIS) and tafel... 

Surface modification is an important property of nano particles. In this project surface of silica nano particles modified with hydrophobic and hydrophilic groups to imrprove surface activity of nano particles. Purpose of this project is to study surface activity of surface modified silica nano particles in different temperatures from 20 to 70 degree centigrade. Also effect of salt and time on the surface activity is studied. At first nano particles modified just with haydrophobic groups and then just with hydrophilic groups (hydrophobic and hydrophilic nano particles) and after that, the surface modification done with both hyadrophilic and hydrophobic groups (amphiphilic nanoparticles).... 

Electrodeposition is an old, well known and conventional science surface modification method to improve the surface characteristics, decorative and functional, of a wide variety of materials. This science is considered in nanotechnology as a bottom-up method for fabrication of one, two and three-dimensional nanomaterials. A great variety of secondary components can be added to plating baths resulting in metallic matrix composite and nanocomposite coatings production. Low amounts of iron addition for alloying zinc coatings, significantly increases the corrosion resistance of this generally used metal economically. Superhydrophobic coatings on metallic substrates have shown, during the past... 

Among the methods for increasing chemical oil extraction,the polymeric flood method has the most commercialization capability.However,most commonly used polymers such as Hydrolyzed Polyacrylamide (HPAM) are not able to withstand high levels of salinity and high temperatures.To overcome these problems,in this project,new types of polymer nanostructures were synthesized with hydrophobic groups consisting of styrene (hydrophilic monomer) and malic anhydride (hydrophilic monomer) acrylamide (hydrophilic monomer). These polymers were synthesized by reversible mini-emulsion by adjusting the synthesis conditions for the purpose of producing the terpolymer with suitable conditions for tolerating... 

The integrated development of small-scale electronic and mechanical systems has drawn attention, since they lead to increase in speed and decrease in volume of industry dimensions in the manufacturing sector. That is why microelectromechanical systems are highly considered. MEMS are widely used in Microfluidic systems that can be used in medicine, biology and drug injection. Due to the fact that consistent fluid velocity is necessary in biological applications, electroosmotic flow is more important than ever. To investigate the behavior of biofluids, Newtonian models cannot be used and it is required to use models that predict the behavior of these fluids accurately. In this research... 

Electrophoresis of colloidal and bio-particles, which is the motion of a charged particle under an electric field, is a powerful method for the characterization and separation of particles. Electrophoresis of particles could be in electrolyte and gel mediums. Additional drag force is exerted on the particle in a gel medium due to the 3D polymeric structure. Experimental research and molecular dynamics simulations have shown that the no-slip boundary condition is not valuable for many particles in micro and nano-devices. The Navier slip condition, which represents the amount of slip, must replace the no-boundary condition. Characterization of hydrophobicity for optimal design in microfluidic... 

Among chemical enhanced oil recovery (CEOR) methods, polymer flooding has the highest commercial potential. However, the most widely used conventional polymers such as partially hydrolyzed polyacrylamide (HPAM) are not applicable for high temperature and high-salinity reservoirs. To overcome above mentioned problems, in this work, a series of water- soluble hydrophobically modified polymers (HMPs) nanostructures comprising styrene (hydrophobic monomer) and acrylamide (hydrophilic monomer) have been produced. The copolymers have been synthesized using inverse miniemulsion synthesis method by adjusting synthesis conditions to optimize solution characteristic of copolymers for applying under... 

Among chemically enhanced oil recovery (CEOR) methods, polymer flooding has the highest commercial potential. However, the most widely used conventional polymers such as partially hydrolyzed polyacrylamide (HPAM) are not applicable for high-temperature and high-salinity reservoirs. To overcome above-mentioned problems, in this work, a series of water-soluble hydrophobically modified polymers (HMPs) nanostructures comprising 2-vinyl naphthalene (hydrophobic monomer) has been produced by freestyle method (without Surfactant), micellar (with Surfactant). The size of the particles was investigated using scanning electron microscopy (FE-SEM) and optical scattering (DLS). Results from FT-IR... 

The purpose of this project is to design a water-based drilling fluid for use in high-pressure and high-pressure conditions (Deep Drilling). This goal is usually achieved by adding the resistant polymers to the ambient conditions (temperature stability) to the drilling fluid (here the blue base fluid), and then the rheological properties of the fluid are studied. The stability of the rheological properties of the fluid in high temperature and high pressure conditions is not constant. In this situation, a sequence of events occurs, for example, decreases with increasing viscosity and turbulence, and hence the reduction of drilling fractures and the efficiency of the bottom of the well is... 

With the rapid increase of energy consumption, energy problem has been a global issue, which must be faced with and solved. One way to prevent energy consumption is to reduce drag in the flow inside the pipes by using polymer additives; Because the Transportation of liquids using pipeline technology has its limitations, since turbulent flow inside the pipe involves a loss of energy. The net effect of this is that increasing the energy applied to the flow does not increase the flow rate. For this purpose, copolymers and terpolymers of hydrophilic acrylamide monomers along with hydrophobic styrene and hydrophilic maleic anhydride monomers were synthesized by reverse emulsion polymerization... 

increased cohesion up to 4H pencil. Results of immersion test in water showed stability of coatings. Polarization test in naphtha and water mixture for stainless steel, copper and aluminum meshes demonstrated 98.89%, 86.25% and 66.6% protection efficiency respectively. In order to study of oil and water separation efficiency, mixtures of water and naphtha with different content of naphtha were used. Separation test for 200μm St.St mesh in different slopes demonstrated that changing of slop increase separation efficiency up to 95.5% for water and up to 100% for naphtha. Separation test for meshes with different pore size demonstrated that meshes with small pore size are more appropriate for... 

In recent years, utilizing the colloidal gas aphron (CGA) drilling fluids is getting more and more commonplace due to their little formation damage and filtration loss. This study tries to investigate the effect of presence of nanoparticles and their type (hydrophobicity) on stability and performance of water and oil based CGA drilling fluids. This is done through analyzing stability, filtration, rheology, and pore blockage tests. Water and oil based CGA drilling fluids consisted of stabilizer, surfactant, and nanoparticles are generated and through examining of the effects of polymer, surfactant, and nanoparticle concentrations, the optimum formulation is obtained. High pressure-high... 

With the advancement of the industry, microscale devices use due to its unique characteristics. On the other hand, it is essential to find ways to reduce drag inside microchannels because of The importance of energy. One of the methods is to optimize the contact surface using structured geometric surfaces. These hydrophobic surfaces reduce drag by trapping the air in roughness and creating a two-phase flow. The purpose of this project is to reduce the drag within the microchannel using structured geometric surfaces for non-Newtonian and multiphase flows. In most previous studies, with simplification, Newtonian and two-phase flows have been investigated. While most industrial fluids show... 

Membrane proteins aggregation is a very important biological phenomenon in a variety of cell functions. It has been suggested that aggregation behavior of membrane proteins is influenced by the shape of the hydrophobic domain of the proteins, proteins hydrophobic mismatch and bilayer curvature. However, in this study by means of coarse grained membrane simulations it has been found that in thermal equilibrium, protein-protein interactions also depend on protein rigidity and structural strength. Based on simulation results, we have observed stable large clusters even in the absence of hydrophobic mismatch between lipids and proteins. Interestingly, our results also indicate that proteins with... 

Due to their unique characteristics, such as drag reduction, anti-fouling, and enhancing condensation, hydrophobic and superhydrophobic surfaces have attracted a lot of attention in the past decades. Since approximately 4% of the fossil fuel usage and 14-19% of the air pollution (including greenhouse gases, sulfur, and so forth) are attributed to naval activities, and the dominant form of drag on vessels is friction, drag reduction will not only reduce the cost and usage of fossil fuels, but it will also have numerous environmental benefits  

In this research, a coating was created on the steel surface using the network structure of zeolite imidazolate-8 (ZIF-8) and its effect on the corrosion behavior of steel was investigated. Then, the effect of two coupling agents, mercaptopropyltriethoxysilane (MPTES) and aminopropyltriethoxysilane (APTES) on the coating and its anti-corrosion properties was investigated. Then, in order to make a hydrophobic coating, the substrate was first coated with ZIF-8 and then a combination of silica nanoparticles plus hexamethyldisilazane (HMDS) and polymethylhydrogensiloxane (PMHS) was added to the initial solution and then coating was done. As a result of this process, the contact angle of water... 

Hydrophobic and superhydrophobic surfaces find many applications in different fields of science. The aerospace industry is one such field that can take the advantage of superhydrophobicity for anti-icing coatings. In order to make hydrophobic and superhydrophobic surfaces on hydrophilic materials, two-step process is usually need, at first, making a rough surface and then modifying it with hydrophobic coatings with low surface free energy. In this research, we have used glancing angle deposition (GLAD) RF sputtering technique to fabricate Teflon coated tungsten on glass substrate for obtaining hydrophobic surface. GLAD approach is a method to grow structures such as nanorods and zigzag... 

All the biological diagnostic devices that are introduced to the consumers, must meet WHO criteria. Some of these criteria include being affordable, sensitive and deliverable to the user. In the last twenty years, there have been lots of efforts to use microfluidic devices for biological assay. Due to their expensive price and requirement of complex equipment for their fabrication, polymer-based microfluidic devices have not been able to be used in developing countries. It is to be hoped that introduction of paper for fabrication of microfluidic devices could make microfluidic devices meet WHO criteria. μPADs are divided into well-based and channel-based devices. In the present work, both...