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    Irradiation mediated synthesis of a superabsorbent hydrogel network based on polyacrylamide grafted onto salep

    , Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms ; Volume 266, Issue 18 , September , 2008 , Pages 3932-3938 ; 0168583X (ISSN) Rezanejade Bardajee, G ; Pourjavadi, A ; Soleyman, R ; Sheikh, N ; Sharif University of Technology
    The synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with polyacrylamide is described. The new biopolymer was synthesized via simultaneous crosslinking and graft copolymerization of acrylamide monomer onto a salep backbone using radiochemical methods. Various parameters such as relative contents of salep and acrylamide, as well as total dose of γ-rays were examined. The best synthesis condition is reported and a mechanism for superabsorbent hydrogel formation suggested. Factors affecting the swelling behavior of hydrogel were also studied. © 2008 Elsevier B.V. All rights reserved  

    Submicron nanoporous polyacrylamide beads with tunable size for verapamil imprinting

    , Article Journal of Applied Polymer Science ; Volume 125, Issue 1 , 2012 , Pages 189-199 ; 00218995 (ISSN) Nematollahzadeh, A ; Abdekhodaie, M. J ; Shojaei, A ; Sharif University of Technology
    Submicron sized polyacrylamide particles were prepared via modified precipitation polymerization method. Experimental design based on Taguchi approach was employed to study the influence of the polymerization composition including monomer (acrylamide), crosslinker (methylenebisacrylamide), initiator (azobisisobutyronitrile), and modifier (polyvinylpyrrolidone, K-30), on the size and morphology of the particles. Varying the polymerization composition, submicron-particles with sizes ranging between 100 and 600 nm were achieved. In all the cases, polydispersity index (PDI) of the particle size was found to be almost 1 indicating uniformity of the particle size. The concentration of crosslinker... 

    Synthesis of Bone graft Substitute for Clinical Applications

    , M.Sc. Thesis Sharif University of Technology Khodabakhshi Tabar Ahangar, Zahra (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor)
    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... 

    Synthesis, characterization and comparison of PAM, cationic PDMC and P(AM-co-DMC) based on solution polymerization

    , Article Journal of Industrial and Engineering Chemistry ; Volume 17, Issue 3 , 2011 , Pages 580-586 ; 1226086X (ISSN) Abdollahi, Z ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
    High molecular weight homopolymers of acrylamide (PAM) and (2-methacryloyloxyethyl) trimethyl ammonium chloride (PDMC) and copolymer of DMC with acrylamide (P(AM-co-DMC)) were synthesized using solution polymerization technique. The synthesized polymers were characterized by Fourier transform infrared (FTIR), 1HNMR, 13CNMR spectroscopy and differential scanning calorimetry (DSC) and viscometery. 1HNMR and 13CNMR studies confirmed the structure of the synthesized polymers. The behavior of the synthesized polymers was investigated in water-acetone and water-methanol mixtures. The plot of intrinsic viscosity of either PAM or P(AM-co-DMC) with respect to acetone (methanol)/water ratio 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) Abdi, A ; Shahrokhi, M ; Ahmad Ramazani, S. A ; Vafa, E ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    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... 

    A new functionalized magnetic nanocomposite of poly(methylacrylate) for the efficient removal of anionic dyes from aqueous media

    , Article RSC Advances ; Volume 6, Issue 10 , 2016 , Pages 7982-7989 ; 20462069 (ISSN) Pourjavadi, A ; Abedin Moghanaki, A ; Nasseri, S. A ; Sharif University of Technology
    Royal Society of Chemistry 
    A new magnetic nano-adsorbent was synthesized via the radical polymerization of methyl acrylate on modified Fe3O4 nanoparticles, followed by its functionalization by amidation of the methyl ester groups using pentaethylenehexamine, to create active adsorption sites for removing anionic dyes from aqueous media. Physicochemical properties of the adsorbent were then characterized by SEM, TEM, XRD, FTIR, TGA and CHN analysis. The prepared nanocomposite was used as adsorbent for the removal of anionic dyes, naphthol green B and chromeazurol S, from aqueous solution and assessed in view of the kinetics and isotherm adsorption, and the effect of solution pH, contact time and initial dye... 

    Preparation of porous graphene oxide/hydrogel nanocomposites and their ability for efficient adsorption of methylene blue

    , Article RSC Advances ; Volume 6, Issue 13 , 2016 , Pages 10430-10437 ; 20462069 (ISSN) Pourjavadi, A ; Nazari, M ; Kabiri, B ; Hosseini, S. H ; Bennett, C ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Porous nanocomposite hydrogels were prepared using CaCO3 particles as solid porogens. The hydrogels were prepared by polymerization and grafting of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid onto the starch in the presence of CaCO3 and graphene oxide. CaCO3 solid porogens were then removed by washing with acid and porous structures were obtained. The prepared hydrogels were used as adsorbents for methylene blue as a model cationic dye; and a very high adsorption capacity, up to 714.29 mg g-1, was obtained. Kinetics and isotherms of adsorption and the effect of porosity of hydrogel as well as other experimental conditions were also investigated. The prepared adsorbents were... 

    A thermodynamically-consistent large deformation theory coupling photochemical reaction and electrochemistry for light-responsive gels

    , Article Journal of the Mechanics and Physics of Solids ; Volume 116 , July , 2018 , Pages 239-266 ; 00225096 (ISSN) Dehghany, M ; Zhang, H ; Naghdabadi, R ; Hu, Y ; Sharif University of Technology
    Elsevier Ltd  2018
    Gels are composed of crosslinked polymer network and solvent molecules. When the main chain network is incorporated with functional groups that can undergo photo-chemical reaction upon light irradiation, the gel becomes light-responsive. Under irradiation, the photosensitive groups may undergo photo-ionization process and generate charges that are attached to the main chain or diffuse into the solvent. The newly generated ions disturb the osmotic balance of the gel medium. As a result, water molecules and mobile ions are driven into or out of the network to compensate the osmotic imbalance, which eventually leads to macroscopic swelling or shrinking of the gel. In this work, we develop a... 

    Ethylenediamine grafting to functionalized NH2-UiO-66 using green aza-Michael addition reaction to improve CO2/CH4 adsorption selectivity

    , Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 20 , April , 2018 , Pages 7030-7039 ; 08885885 (ISSN) Molavi, H ; Ahmadi Joukani, F ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2018
    Three versions of zirconium-based metal organic frameworks, NH2-UiO-66, GMA-UiO-66, and EDA-UiO-66, were synthesized and employed as adsorbent for CO2/CH4 separation. GMA-UiO-66 was synthesized via a ring opening reaction between the amine species in the framework and epoxy groups in glycidyl methacrylate (GMA), while the green aza-Michael addition reaction was used for the first time to functionalize GMA-UiO-66 with ethylenediamine (EDA). The products were characterized by BET, XRD, TGA, FESEM, ICP-OES, 1H NMR, mass spectroscopy, and FTIR-ATR methods to monitor their textural properties before and after functionalization. The results indicated that GMA was successfully grafted to the... 

    Smart pectin-based superabsorbent hydrogel as a matrix for ibuprofen as an oral non-steroidal antiinflammatory drug delivery

    , Article Starch/Staerke ; Volume 61, Issue 3-4 , 2009 , Pages 173-187 ; 00389056 (ISSN) Pourjavadi, A ; Barzegar, S ; Sharif University of Technology
    The purpose of this study was to produce an intelligent superabsorbent polymer (SAP) to be used as a pH sensitive matrix for the controlled delivery of drugs. Novel types of highly swelling SAPs were prepared by grafting crosslinked acrylic acid-co-acrylamide (AA-co-AAm) chains onto pectin by free-radical polymerization. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The controlled release behavior of ibuprofen (IBU) from the superabsorbent polymer was investigated. SAP structural-property relationships that affect its controlled release behavior were determined. Analysis of the results indicated that it... 

    Mixed-matrix composite membranes based on uio-66-derived MOFs for CO 2 separation

    , Article ACS Applied Materials and Interfaces ; Volume 11, Issue 9 , 2019 , Pages 9448-9461 ; 19448244 (ISSN) Molavi, H ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2019
    We demonstrated a novel mixed-matrix composite membrane (MMCM) based on acrylated polyurethane (APU) and UiO-66 nanoparticles to separate CO 2 /N 2 mixture. UiO-66 and functionalized UiO-66 including NH 2 -UiO-66 and glycidyl methacrylate (GMA)-UiO-66 were loaded into APU/2-hydroxyethyl methacrylate (APUH) matrix at variable concentrations between 3 and 30 wt %. APUH/GMA-UiO-66 MMCMs exhibited strong adhesion with a support layer of polyester/polysulfone, which was not deteriorated after immersion in water for a long time (20 days). Incorporation of UiO-66 and its functionalized forms increased simultaneously permeability and CO 2 /N 2 selectivity, which were indeed superior in comparison... 

    Magnetic and light-responsive nanogels based on chitosan functionalized with Au nanoparticles and poly(: N-isopropylacrylamide) as a remotely triggered drug carrier

    , Article New Journal of Chemistry ; Volume 44, Issue 40 , 2020 , Pages 17302-17312 Pourjavadi, A ; Doroudian, M ; Bagherifard, M ; Bahmanpour, M ; Sharif University of Technology
    Royal Society of Chemistry  2020
    In the past few years, laser-assisted methods have greatly influenced biomedical studies due to less invasive ways of treatment and higher precision. New stimuli-responsive drug carriers are still explored by scientists to achieve a better spatiotemporal control of drug carriers by using visible to NIR light instead of phototoxic ultra-violet irradiation. Due to their biocompatibility and high loading capacity of hydrophilic drugs, hydrogels have been used extensively in this area. However, poor cellular uptake and restricted loading of hydrophobic drugs are challenges that should be addressed. In this study, a previously known nanogel system based on chitosan and poly(N-isopropylacrylamide)... 

    Hydrolyzed collagen-based hydrogel with salt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 106, Issue 4 , 2007 , Pages 2371-2379 ; 00218995 (ISSN) Pourjavadi, A ; Salimi, H ; Kurdtabar, M ; Sharif University of Technology
    A novel hydrolyzed collagen-based hydrogel has been prepared by grafting the binary mixture of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto the collagen backbone in the presence of a cross-linking agent. Its physicochemical properties in aqueous solution were studied. The effect of reaction variables on both gel content and swelling capacity was investigated to achieve a hydrogel with improved absorbency and gel content. The absorbency under load of optimized hydrogel was also investigated by using an absorbency under load tester at various applied pressures. The swelling ratio in various salt solutions was also determined and additionally, the swelling of hydrogels was... 

    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... 

    Hydrophobic nanocarriers embedded in a novel dual-responsive poly(N-isopropylacrylamide)/chitosan/(cyclodextrin) nanohydrogel

    , Article Journal of Polymer Research ; Volume 20, Issue 10 , 2013 ; 1572-8935 (Online ISSN) Bashari, A ; Hemmatinejad, N ; Pourjavadi, A ; Sharif University of Technology
    The incorporation of modified β-cyclodextrin (β-CD) into a poly(N-isopropylacrylamide) (PNIPAAm)/chitosan (PNCS) nanohydrogel was studied. β-CD was functionalized with acrylic groups, with different numbers of vinyl bonds added per β-CD molecule. The surfactant-free dispersion polymerization (SFDP) semi-batch method was used to synthesize the nanohydrogel. Increasing the number of vinyl groups per β-CDAC (β-CD acrylate) molecule induced the formation of smaller nanogels with diameters ranging from 142 to 68 nm. The cyclodextrin-modified dual-responsive nanogels obtained presented an LCST (lower critical solution temperature) in aqueous medium at around 31 C. The incorporation of β-CDAC into... 

    Synthesis and characterization of a novel (salep phosphate)-based hydrogel as a carrier matrix for fertilizer release

    , Article Reactive and Functional Polymers ; Volume 72, Issue 10 , 2012 , Pages 667-672 ; 13815148 (ISSN) Pourjavadi, A ; Doulabi, M ; Soleyman, R ; Sharif, S ; Eghtesadi, S. A ; Sharif University of Technology
    Elsevier  2012
    Salep phosphate modified biopolymers with different phosphate contents were prepared via reacting salep (a multi-component polysaccharide obtained from dried tubers of certain natural terrestrial orchids) with a solution of primary and secondary sodium phosphates under basic conditions in a semidry process. Structural characterization of salep phosphates were carried out by 31P NMR, FT-IR spectra and TGA curves. Determination of the phosphate content in samples was done by a standard spectrophotometric method. Then, novel (salep phosphate)-based hydrogels were synthesized by graft copolymerization of acrylic acid (AA) monomer onto salep phosphate backbones. Effect of the phosphate contents... 

    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) Tamsilian, Y ; Ramazani, S. A. A ; Khosravi, N ; Sharif University of Technology
    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... 

    Preparation of acrylated agarose-based hydrogels and investigation of their application as fertilizing systems

    , Article Journal of Applied Polymer Science ; Volume 122, Issue 4 , November , 2011 , Pages 2424-2432 ; 00218995 (ISSN) Pourjavadi, A ; Sadat Afjeh, S ; Seidi, F ; Salimi, H ; Sharif University of Technology
    In this study, we attempt to synthesize novel acrylated agarose (ACAG)-based hydrogels with three different crosslinking densities. Acrylate groups were inserted onto agarose (AG) backbone through homogeneous reaction of acrylic monomers with AG backbone. Hydrogels were synthesized through radical copolymerization of a mixture of acrylic acid and 2-hydroxyethyl acrylate with ACAG in aqueous solution using ammonium persulfate as an initiator. Infrared spectroscopy (FTIR) was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was assessed by scanning electron microscopy. The equilibrium swelling capacities of synthesized hydrogels were evaluated... 

    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) Pourjavadi, A ; Eftekhar Jahromi, P ; Seidi, F ; Salimi, H ; Sharif University of Technology
    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... 

    Inhomogeneous and homogeneous swelling behavior of temperature-sensitive poly-(N-isopropylacrylamide) hydrogels

    , Article Journal of Intelligent Material Systems and Structures ; Volume 27, Issue 3 , 2016 , Pages 324-336 ; 1045389X (ISSN) Mazaheri, H ; Baghani, M ; Naghdabadi, R ; Sharif University of Technology
    SAGE Publications Ltd 
    The aim of this work is to develop a model to continuously predict inhomogeneous and homogeneous swelling behavior of temperature-sensitive poly-(N-isopropylacrylamide) hydrogels. Employing this model, some benchmark homogeneous problems such as free, unidirectional constrained and biaxial constrained swelling as well as swelling of core-shell structures are investigated. The main advantage of the model is its ability to solve inhomogeneous deformations due to a stable behavior in the vicinity of the phase transition temperature. Therefore, inhomogeneous swelling of a spherical shell on a hard core with application to microfluidics is analytically and numerically investigated for various...