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Simulation and Control of Particle Size Distribution in a Continuous Emulsion Polymerization Reactor
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
In this work, a comprehensive dynamic model has been used for vinyl acetate emulsion polymerization in a continuous reactor to predict the evolution of product particle size distribution under isothermal condition. Method of finite-volume has been applied for solving the population balance equations and the results are compared with the results obtained from moment method. Finite-volume method has been selected as a precise technique to predict sustained oscillations, which occurs in continuous emulsion polymerization. After performing sensitivity analysis and verification of system’s controllability, feed rate of surfactant and initiator have been selected as proper manipulated variables to...
Synthesis and Investigation of Properties of Intumescent Fireproofing Paint with Oxide Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Intumescent paints are coatings designed for passive fire protection of steel and other materials. In this research, the performance of water-based intumescent coating with vinyl acetate resin for cellulose fire conditions and epoxy-based coatings for hydrocarbon fire conditions has been investigated. The fire resistance of coatings was evaluated according to the ASTM E119 standard for water-based coating and UL1709 standard for epoxy-based intumescent coating. For the water-based intumescent coating, the expansion of char was investigated in a furnace with a temperature of 800°C for 1 hour. Thermal decomposition was studied by thermogravimetric analysis (TGA). Also, flammability was...
Synthesis of Bone graft Substitute for Clinical Applications
, M.Sc. Thesis Sharif University of Technology ; Abdekhodaie, Mohammad Jafar (Supervisor)
Abstract
The natural tissue of the bones consists of organic and inorganic parts. The bone mineral part contains calcium phosphate and its organic part is mainly of collagen fibers. The combination of these fibers and calcium phosphate makes the bone flexible and resistant to stresses. Many conditions, including osteoporosis and crashes, lead to fractures and cavities in bone. Bone cements are the most used materials used in orthopedic surgeries and spinal cord.The purpose of this study was to synthesis acrylic bone cement with properties determined by ASTM F 451 and Iso5833 for orthopedic applications, including joint replacement. Polymethyl methacrylate polymer was synthesized as the main component...
Mechanical Properties of Actin Assemblies
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Actin filaments are the most abundant component of the cellular cytoskeleton and provide shape for the most eukaryotic cells. Actin constitutes 1-10% of the total protein in most cells and is present at even higher concentrations in muscle cells. The functions of actin are directly connected to its mechanical properties, therefore both experimental and computational understanding of the mechanical properties of actin filaments are essential to elucidate their functions in cells and muscles. Actin exists in two forms, actin monomers (G-actin) and actin filaments (F-actin), which have continuous polymerization and depolymerization processes. In the polymerization process, different...
Ultrafast and efficient removal of cationic dyes using a magnetic nanocomposite based on functionalized cross-linked poly(methylacrylate)
, Article Reactive and Functional Polymers ; Volume 105 , 2016 , Pages 95-102 ; 13815148 (ISSN) ; Abedin Moghanaki, A ; Sharif University of Technology
Elsevier
2016
Abstract
In this study, a new magnetic nanocomposite was synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the functionalization of the methyl ester groups with ethylenediamine and sodium chloroacetate. The generated magnetic nanocomposite was characterized by FT-IR, TEM, SEM, TGA, VSM, XRD and elemental analysis. Its key role as an adsorbent for the removal of typical cationic dyes, methyl violet and malachite green was investigated in terms of pH, contact time and initial dye concentration. The resulted adsorbent displays excellent adsorption capacities for cationic dyes which are more effective than most of the adsorbents reported so far....
The role of mscl amphipathic n terminus indicates a blueprint for bilayer-mediated gating of mechanosensitive channels
, Article Nature Communications ; Volume 7 , 2016 ; 20411723 (ISSN) ; Cortes, D. M ; Cox, C. D ; Rohde, P. R ; Liu, W ; Deitmer, J. W ; Bavi, O ; Strop, P ; Hill, A. P ; Rees, D ; Corry, B ; Perozo, E ; Martinac, B ; Sharif University of Technology
Nature Publishing Group
2016
Abstract
The bacterial mechanosensitive channel MscL gates in response to membrane tension as a result of mechanical force transmitted directly to the channel from the lipid bilayer. MscL represents an excellent model system to study the basic biophysical principles of mechanosensory transduction. However, understanding of the essential structural components that transduce bilayer tension into channel gating remains incomplete. Here using multiple experimental and computational approaches, we demonstrate that the amphipathic N-terminal helix of MscL acts as a crucial structural element during tension-induced gating, both stabilizing the closed state and coupling the channel to the membrane. We...
The preparation and rheological investigation of polymer and hydrogel modified drilling mud
, Article Petroleum Science and Technology ; Volume 30, Issue 10 , 2012 , Pages 1059-1068 ; 10916466 (ISSN) ; Ramazani, S. A. A ; Khosravi, N ; Sharif University of Technology
2012
Abstract
The authors carried out the study to prepare chitosan N-isopropylacrylamide hydrogel via heating and radiation processes. Properties investigation of prepared samples revealed that radiation prepared samples show higher yield and swelling ratios in comparison with the heating prepared ones. Effects of hydrogel addition to drilling mud on its important rheological properties such as apparent viscosity, plastic viscosity, and stress-strain behavior are measured. The rheological properties of hydrogel were compared with cellulosemethylcarboxyl and resins that are widely used in drilling fluid. The results demonstrate that whereas linear polymer effects on mud properties are more significant in...
Theoretical and experimental investigations of the inverse emulsion polymerization of acrylamide
, Article Journal of Applied Polymer Science ; Volume 132, Issue 22 , February , 2015 ; 00218995 (ISSN) ; Shahrokhi, M ; Ahmad Ramazani, S. A ; Vafa, E ; Sharif University of Technology
John Wiley and Sons Inc
2015
Abstract
In this study, the inverse emulsion polymerization modeling of polyacrylamide with population balance equations (PBEs) was performed. The PBEs were derived on the basis of the zero-one kinetic model. The effects of the surfactant steric barrier and surfactant reaction with radicals, including monomeric radicals, on the radical entry rate into the particle were taken into account. In the modified model, the coagulation phenomenon was included through consideration of the effects of forces not included in the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory; these include hydration and steric forces in addition to DLVO forces. The effects of the surfactant and initiator concentrations on...
Temperature sensitive superabsorbent hydrogels from poly(N-t-butyl acrylamide-co-acrylamide) grafted on sodium alginate
, Article Macromolecular Symposia ; Volume 274, Issue 1 , December , 2008 , Pages 177-183 ; 10221360 (ISSN) ; Samadi, M ; Ghasemzadeh, H ; Sharif University of Technology
2008
Abstract
Temperature-sensitive hydrogels based on N-t-butylacrylamide (TBA), acrylamide (AAm), and sodium alginate were prepared by free radical polymerization method. Methylenebisacrylamide (MBA) and amonium persulfate (APS) were applied as water soluble crosslinker and initiator, respectively. The chemical structure of the hydrogels was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TCA) methods. Morphology of the samples was examined by scanning electron microscopy (SEM). By changing the initial TBA/AAm mole ratios, hydrogels with different swelling properties were obtained. The rate parameters were found to be 2.0, 2.4, and 3.5 min for the superabsorbents with AAm/TBA weight...
Synthesis of poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite for removal of lead contaminant from aqueous media
, Article International Journal of Environmental Science and Technology ; Volume 13, Issue 10 , 2016 , Pages 2437-2448 ; 17351472 (ISSN) ; Abedin Moghanaki, A ; Hosseini, S. H ; Sharif University of Technology
Center for Environmental and Energy Research and Studies
2016
Abstract
Poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the functionalization of the methyl ester groups with poly(amidoamine) dendrimer. The resulting poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was then characterized by infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, scanning electron microscope and X-ray diffraction analysis. Its application as an adsorbent for the removal of Pb(II) ions was studied. The removal capability of the adsorbent was investigated in different pH values, contact time (kinetics) and...
Synthesis of a custom-made suspension of preformed particle gel with improved strength properties and its application in the enhancement of oil recovery in a micromodel scale
, Article Journal of Petroleum Science and Engineering ; Volume 207 , 2021 ; 09204105 (ISSN) ; Baghban Salehi, M ; Taghikhani, V ; Pahlevani, H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The objective of this work is to develop a new Preformed Particle Gel (PPG) suspension to enhance oil production and monitor water production in a porous medium on micromodel scale. To achieve the above goal, the following synthetic method was used. At the outset, the PPG samples were synthesized with polyethylene amine (PEI) as a crosslinker, 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (AAPH) as initiator and acrylamide (AM) and 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) monomers to improve the strength properties of PPGs by the radical polymerization method. Also, to characterize the micro and macro structural the samples, the scanning electron microscopy (SEM),...
Synthesis and swelling behavior of a new superabsorbent hydrogel network based on polyacrylamide grafted onto salep
, Article Journal of Applied Polymer Science ; Volume 112, Issue 5 , 2009 , Pages 2625-2633 ; 00218995 (ISSN) ; Rezanejade Bardajee, G ; Soleyman, R ; Sharif University of Technology
2009
Abstract
Synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with Polyacrylamide is described. The new superabsorbent hydrogel biopolymer was synthesized via radical crosslink-ing and graft copolymerization of acrylamide monomer onto salep backbones. Regarding to the water absorption of hydrogel, the best synthesis condition is reported. FTIR spectroscopy and thermogravimetric analysis were used to confirm the structure of the final product and a mechanism for superabsorbent hydrogel formation was also suggested. After preparing the desired hydrogels based on optimum condition, several factors affecting the swelling behavior of hydrogel including pH of...
Synthesis and swelling behavior of acrylatedstarch-g-poly (acrylic acid) and acrylatedstarch-g-poly (acrylamide) hydrogels
, Article Carbohydrate Polymers ; Volume 79, Issue 4 , 2010 , Pages 933-940 ; 01448617 (ISSN) ; Eftekhar Jahromi, P ; Seidi, F ; Salimi, H ; Sharif University of Technology
Abstract
In the present work, synthesis and swellability of acrylatedstarch-based hydrogels was investigated. Acrylic groups were introduced onto starch backbone by a homogeneous synthesis to produce starch monomers with three different degree of substitution (DS). The radical copolymerization of acrylatedstarch (AST) with acrylic acid (AA) and acrylamide (AAm) was carried out in aqueous solution using ammonium persulfate (APS) as an initiator. Infrared spectroscopy (FT-IR) and TGA thermal analysis were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). Their equilibrium swelling degree was evaluated...
Synthesis and properties of partially hydrolyzed acrylonitrile-co- acrylamide superabsorbent hydrogel
, Article Bulletin of the Korean Chemical Society ; Volume 31, Issue 11 , 2010 , Pages 3163-3172 ; 02532964 (ISSN) ; Hosseinzadeh, H ; Sharif University of Technology
2010
Abstract
In this work, a novel method to synthesis of an acrylic superabsorbent hydrogel was reported. In the two stage hydrogel synthesis, first copolymerization reaction of acrylonitrile (AN) and acrylamide (AM) monomers using ammonium persulfate (APS) as a free radical initiator was performed. In the second stage, the resulted copolymer was hydrolyzed to produce carboxamide and carboxylate groups followed by in situ crosslinking of the polyacrylonitrile chains. The results from FTIR spectroscopy and the dark red-yellow color change show that the copolymerization, alkaline hydrolysis and crosslinking reactions have been do take place. Scanning electron microscopy (SEM) verifies that the synthesized...
Synthesis and properties of multi-stimuli-responsive water-soluble hyperbranched polymers prepared via reversible addition-fragmentation chain transfer self-condensing vinyl polymerization
, Article ACS Applied Polymer Materials ; 2021 ; 26376105 (ISSN) ; Kohestanian, M ; Pourjavadi, A ; Vazifehkhorani, H. H ; Mehrali, M ; Sharif University of Technology
American Chemical Society
2021
Abstract
Multistimuli-responsive hyperbranched polymers were synthesized in one-step polymerization using reversible addition-fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP). These hyperbranched polymers responded to UV-vis or sunlight, pH changes, and temperature changes. 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid known as DDMAT participated in esterification with 2-hydroxyethyl methacrylate to obtain a chain transfer monomer in the name of 2-((2-(((dodecylthio)carbonothioyl)thio)-2-methylpropanoyl)oxy)ethylmethacrylate (MACDT). For the first time, smart hyperbranched polymers were produced with the RAFT-SCVP method in one step by using...
Synthesis and properties of multi-stimuli-responsive water-soluble hyperbranched polymers prepared via reversible addition-fragmentation chain transfer self-condensing vinyl polymerization
, Article ACS Applied Polymer Materials ; Volume 4, Issue 1 , 2022 , Pages 692-702 ; 26376105 (ISSN) ; Kohestanian, M ; Pourjavadi, A ; Vazifehkhorani, H. H ; Mehrali, M ; Sharif University of Technology
American Chemical Society
2022
Abstract
Multistimuli-responsive hyperbranched polymers were synthesized in one-step polymerization using reversible addition-fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP). These hyperbranched polymers responded to UV-vis or sunlight, pH changes, and temperature changes. 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid known as DDMAT participated in esterification with 2-hydroxyethyl methacrylate to obtain a chain transfer monomer in the name of 2-((2-(((dodecylthio)carbonothioyl)thio)-2-methylpropanoyl)oxy)ethylmethacrylate (MACDT). For the first time, smart hyperbranched polymers were produced with the RAFT-SCVP method in one step by using...
Synthesis and investigation of swelling behavior of grafted alginate/alumina superabsorbent composite
, Article Starch/Staerke ; Volume 60, Issue 9 , 9 September , 2008 , Pages 457-466 ; 00389056 (ISSN) ; Farhadpour, B ; Seidi, F ; Sharif University of Technology
2008
Abstract
In this study a novel alginate-g-poly(acrylic acid)/alumina composite was synthesized and characterized. Preparation of the composite hydrogels involved free radical polymerization of a combination of alginate, acrylic acid (AA) and distilled water, in appropriate amounts and N,N-methylene bisacrylamide (MBA) as crosslinking agent. The composite formation was confirmed by Fourier transform infrared spectroscopic (FTIR). The surface morphologies of the synthesized hydrogels were assessed by scanning electron microscopy. Systematically, the different variables of the graft copolymerization were optimized to achieve maximum swelling capacity. The swelling of superabsorbent hydrogels was...
Synthesis and characterization of multi stimuli-responsive block copolymer-silica hybrid nanocomposite with core-shell structure via RAFT polymerization
, Article Composites Science and Technology ; Volume 188 , 2020 ; Rahemipoor, S ; Kohestanian, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
A novel multi stimuli-responsive silica nanocomposite with a core-shell structure is synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. The SiO2 nanoparticles are chemically modified via 3-(trimethoxylsilyl) propyl methacrylate (MPS) which they are used in the core of nanocomposite. The macro-RAFT agent is prepared by RAFT polymerization of N-isopropylacrylamide (NIPAM), spirooxazine acryloyl monomer (SOM), and 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT as a RAFT agent). Finally, the smart nanocomposite is prepared by reaction between the macro-RAFT agent and 2-(Dimethylamino) ethyl methacrylate (DMAEMA) as a monomer. SOM as a...
Synthesis and characterization of molybdenum (VI) complex immobilized on polymeric Schiff base-coated magnetic nanoparticles as an efficient and retrievable nanocatalyst in olefin epoxidation reactions
, Article Applied Organometallic Chemistry ; Volume 34, Issue 3 , 2020 ; Bagherzadeh, M ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
In this study, a new polymeric functionalized magnetic nanocatalyst containing a molybdenum Schiff base complex was prepared using a few consecutive steps. Poly (methylacrylate)-coated magnetic nanoparticles were synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups with hydrazine. Polymeric functionalization efficiently provides the advantage that more catalytic units can be grafted on the surface of magnetic nanoparticles. The functionalization process was continued with salicylaldehyde which introduced Schiff base groups on to the surface of the polymeric support. In the final step, the desired...
Synthesis and characterization of magnetic hybrid nanomaterials via RAFT polymerization: A pH sensitive drug delivery system
, Article Colloids and Surfaces B: Biointerfaces ; Volume 174 , 2019 , Pages 153-160 ; 09277765 (ISSN) ; Kohestanian, M ; Shirzad, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Herein, a facile and versatile method for the synthesis of a novel magnetic nanocarrier via surface- initiated reversible addition-fragmentation chain transfer (RAFT) polymerization is introduced. At first, RAFT agent was successfully attached to the surface of Fe 3 O 4 nanoparticles and, then, poly (glycidyl methacrylate) (PGMA) chains were grown and anchored onto the surface of Fe 3 O 4 nanoparticles. At the end, hydrazine (Hy) groups were introduced to the PGMA chains via reaction between epoxy rings and hydrazine molecules. Doxorubicin (DOX) was covalently conjugated to the prepared nanocarrier (Fe 3 O 4 @PGMA@Hy) through a hydrazone linkage. The in vitro drug release of Fe 3 O 4...