Sharif Digital Repository

The Flory-Huggins (FH) model has been one of the most used models in theoretical calculations which has been proved to be sensitive to values assigned as interaction parameters. In this work, a predictive equation is implemented to implicitly couple the concept of compressible regular solution theory of Ruzette and Mayes into the original FH model to obtain a new concertation-dependent interaction parameter equation. Then, the modified model (m-FH) is applied for construction of phase diagram of ternary solutions containing polymer/solvent/nonsolvent where experimental data for ternary systems were collected from the literature. In order to compare and analyze the model performance, the... 

In the context of controlled release drug delivery approaches, the systems providing zero-order release kinetics have special advantages. Through employing these systems, drug concentration could be maintained within the therapeutic window over release time; thus maximum effectiveness alongside minimized side effects of the drug are achieved. However, obtaining zero-order drug release is extremely challenging. One of the main obstacles is the fact that implemented devices should be designed to overcome the decreasing mass transfer driving force, especially, in polymeric systems in which diffusion mechanism is dominant. In this study, we developed a new configuration of a polymeric matrix... 

The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties... 

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... 

In this research, the effects of preparation conditions, including the coagulation bath temperature, polymer solution composition, preliminary drying time, and thickness of cast polymeric films, on the morphology of ethylene/vinyl acetate copolymer membranes were investigated with scanning electron microscopy and nitrogen gas permeability tests. Flat sheet membranes were prepared through a thermal-wet phase-inversion method. Scanning electron microscopy pictures showed asymmetric structures for some of the membranes. It was also observed that the porosity of the membranes decreased with an increase in the temperature of the coagulation bath and the solvent evaporation period. When the... 

In the context of peripheral nerve injuries treatment, self-electrical stimuli nerve guidance conduit is a promising technique. To fabricate such structures, PVDF-chitosan–gelatin was considered for the outside walls of conduit and gellan gum containing conductive polyaniline-graphene (PAG) nanocomposite particles in the middle. PVDF-chitosan–gelatin nanofibers were prepared using the dual-electrospinning method and highly conductive binary-doped polyaniline-graphene was synthesized by chemical oxidative polymerization in the presence of aniline and sodium dodecyl sulfate. The morphology and chemical structure of nanofibers and PAG were characterized using SEM and FTIR analyses. The... 

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... 

A novel kappa-carrageenan (κC)-based superabsorbing hydrogel was synthesized through graft copolymerization of acrylamide (AAm) onto a κC substrate in the presence of a crosslinking agent. The crosslinked κC-poly(AAm) polymer graft was partially hydrolyzed in alkaline medium to yield a superabsorbent resin, H-carragPAM. The resin structure was confirmed using FTIR spectroscopy. The variables of graft copolymerization (monomer, initiator, polysaccharide and crosslinker concentration, reaction temperature and time as well as stirrer speed) that affected on the ultimate water-swelling capacity were optimized. The time-temperature variation of the copolymerization was investigated in terms of... 

Synthesis of poly(2,5-dimethoxyanilie) (PDMA) catalyzed by nano reengineered horseradish peroxidase (HRP) with dendritic macromolecules, was studied as a function of reaction media. UV-vis, gel permeation chromatography and conductivity measurements were used to explain how the reaction media compositions influence the physical properties of PDMA. Nanostructured PDMA was also synthesized by oxidative polymerization in a novel and green bi-catalyst system involving HRP and ferric chloride. FTIR and UV-vis analysis confirmed the formation of emeraldine salt state of PDMA. The thermal stability of reengineered HRP granted further studies on the polymerization using bi-catalyst system at... 

The direct electrosynthesis of neutral copper(II) and zinc(II) complexes of a new unsymmetrical carboxamide ligand, N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H2bpabza) derived from 2-pyridinecarboxylic acid and 2-aminobenzylamine, was accomplished by electrochemical oxidation of anodic metals (copper and zinc) in an acetonitrile solution of the ligand. These compounds were characterized by elemental analyses and different spectroscopic methods. The crystal and molecular structures of the ligand, H2bpabza, and its copper complex, Cu(bpabza), were determined by X-ray diffraction. The copper atom adopts a distorted square-pyramidal (4 + 1) CuN2N′N″O coordination geometry with bpabza2-... 

Ultrafiltration (UF) membranes were prepared from blends of poly(vinylidene fluoride) (PVDF)/polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. Polyvinylpyrrolidone (PVP) was used as pore former and hydrophilic polymeric additive. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of different concentrations of PVP on the morphology and performance of the prepared membranes was investigated. Performance of the membranes was evaluated based on pure water flux and filtration of buffered bovine serum albumin (BSA) solution. The contact angle measurements indicated that the hydrophilicity of... 

A new bi-supported Ziegler–Natta catalyst was prepared successfully by supporting TiCl4 on the carbon black (CB) and magnesium dichloride. Then, this catalyst was used to prepare ultrahigh molecular weight polyethylene (UHMWPE) nanocomposites via in situ polymerization. The effects of difference molar ratios of triisobutylaluminum as activator to TiCl4, polymerization temperature, pressure of monomer and polymerization time on productivity of the catalyst were studied. The maximum activity was obtained at [Al]/[Ti] = 121:1. Increasing monomer pressure raised catalyst activity. Increasing temperature to 60 °C increased the polymerization yield; however, the higher temperature decreased the... 

Reverse Osmosis (RO) is a rapid-developing desalination technology; however, it suffers from inefficient energy consumption. To reduce energy consumption, in this study, reverse osmosis thin-film composite membrane (TFC) module was prepared and composed of m-phenylenediamine (MPD), graphene oxide, and 1,3,5-benzenetricarbonyl chloride (TMC) by interfacial polymerization on the surface of a polysulfone substrate. The graphene oxide was embedded in the mentioned thin-film composite by adding it to MPD aqueous solution to enhance permeation flux and, thus, reduce energy consumption. This study assessed the performance of the membrane using a lab-scale RO setup and evaluated permeability and...