Sharif Digital Repository

Novel high capacity swelling nanoporous hydrogel (NPH) was synthesized via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) hybrid backbone, after hydrolysis of this system. The Taguchi method as a strong experimental design tool was used for its optimized synthesis. The Taguchi method was applied for the experimental and standard 9 orthogonal array (OA) with four factors and three levels for each factor. A series of NPHs were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of... 

A novel nano-porous hydrogel (NPH) was synthesized via graft copolymerization of sodium acrylate (Na-AA) and acrylamide (AAm) onto salep backbones and its application as a carrier matrix for oral delivery of tetracycline hydrochloride (TH) was investigated. The Taguchi method as a strong experimental design tool was used for synthesis optimization. The swelling behavior of optimum hydrogel was measured in various media. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetrical analysis (TGA). The study of the surface morphology of the hydrogels using SEM and AFM showed a nanoporous (average pore size: 180. nm) structure for the sample... 

A hydrophilic macromolecular network is prepared by performing graft opolymerization of poly (sodium acrylate) chains onto salep and silica gel. The reaction parameters affecting the water absorbency of the superabsorbent composite were optimized using Taguchi method. FT-IR spectroscopy and Thermo Gravimetric Analysis (TGA) were used for confirming the structure of the final product and morphology of the synthesized superabsorbent composite was examined by SEM. The swelling behavior of optimum superabsorbent composite was measured in various swelling media. In addition, swelling kinetics and on-off switching behavior were investigated. In order to evaluate the controlled release potential of... 

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... 

A novel kind of a biopolymer-based superabsorbent composite, salep-g-poly(sodium acrylate)/alumina, was prepared from salep, sodium acrylate, and alumina by aqueous polymerization, using N,N'-methylenebisacrylamide (MBA) as a cross-linker and ammonium persulfate (APS) as an initiator. The reaction parameters [i.e., acrylic acid (AA), MBA, APS amounts, and neutralization percentage of AA as well as alumina/salep weight ratio] affecting the water absorbency of the hydrogel composite were optimized using systematic method to achieve a composite with high swelling capacity as possible. The swelling behavior of optimum superabsorbent composite was measured in various pH solutions. In addition,... 

The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in... 

A highly swelling nanoporous hydrogel (NPH) was synthesized via UV-irradiation graft copolymerization of acrylic acid (AA) onto salep backbone and its application as a carrier matrix for colonic delivery of tetracycline hydrochloride (TH) was investigated. Optimized synthesis of the hydrogel was performed by the classic method. The swelling behavior of optimum hydrogel was measured in different media. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric analysis (TGA/DTG/DTA). The study of the surface morphology of hydrogels using SEM showed a nanoporous (average pore size: about 350 nm) structure for the sample obtained under... 

N-Benzyl-DABCO-ammonium tribromide was found to be an efficient and recyclable reagent for the deprotection of dithioacetals in dichloromethane/ methanol at room temperature. The reaction can be performed cleanly, in short time, and in high yield. Copyright © Taylor & Francis Group, LLC  

An efficient one-pot synthesis of functionalized trisubstituted thiophenes via the reaction of 3-morpholino-3-thioxopropanenitrile, cyclohexyl isocyanide and -haloketones is reported. This method provides a straightforward route to a variety of highly substituted thiophenes not easily accessible by conventional methods  

A simple, fast and efficient benign procedure has been developed for one-pot synthesis of 2-substituted benzothiazoles in the presence of zirconium(IV) oxide chloride octahydrate (ZrOCl2·8H 2O) and anhydrous copper(II) sulfate. The reaction of 2-aminothiophenol with aldehydes and anhydrides was carried out efficiently in solvent-free conditions with or without microwave irradiation, and adducts were produced in good to excellent yields. © 2006 Wiley Periodicals, Inc  

In the current work, synthesis of an environmental-sensitive superabsorbent hydrogel using γ-rays is described. Grafted polyacrylonitrile onto a homogeneous solution of starch and kappa-Carrageenan hybrid backbones created a smart material with reversible behavior. The reaction parameters (i.e. acrylonitrile, starch and kappa-Carrageenan concentration, as well as γ-irradiation time) affecting the. water absorbency of the. hydrogel were optimized using the. Taguchi method, in order to achieve a hydrogel with high swelling capacity. FTIR spectroscopy was used for confirming the. structure of the final product and the morphology of the synthesized hydrogel was examined by a scanning electron... 

Silver nanostructures are very important agents in biomedical research, because of its unique activity against unfavorable processes in bioscience. In the current study, reagent-free facile preparation of silver nanoparticles (average diameter: 72 nm) and silver nanoparticles/ nanorods hybrid was reported via wet chemical synthesis method. Kappa-carrageenan (kC), a hydrophilic biopolymer with sulphate groups on its backbone, as capping agent was used in the reaction medium. Silver nanoparticles and silver nanoparticles/ nanorods formation was confirmed by SEM images. Further investigations were carried out using DLS data and GPC analysis  

In this report, the synthesis of a novel superabsorbent hydrogel via γ-irradiation graft copolymerization of acrylamide onto sodium alginate and kappa-carrageenan hybrid backbones in a homogeneous solution is described. The Taguchi method was used as a powerful experimental design tool for synthesis optimization. A series of superabsorbent hydrogels was synthesized by proposed conditions of Qualitek-4 software. Considering the results of nine trials according to analysis of variance, optimum conditions were proposed. The swelling behavior of optimum superabsorbent hydrogels was studied in various solutions, with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in... 

In this study, the synthesis and characterization of a novel nano-porous superabsorbent hydrogel with high water swelling capacity is described. A nano-porous hydrogel was prepared by employing (2-dimethylaminoethyl) methacrylate (PDMAEMA) as a pH sensitive monomer and sodium alginate (SA) as a water soluble polysaccharide under γ-ray irradiation. The polymerization reaction was performed at room temperature in the absence of chemically toxic crosslinking agent and initiators. The interactive parameters including biopolymer backbone concentration, monomer concentration and γ-irradiation dose were selected as major factors in the synthesis of superabsorbent and three levels for each factor... 

Various aldehydes have been protected with different thiols as dithioacetals with excellent yields using anhydrous copper sulfate as a mild and chemoselective catalyst. The reaction is carried out in a solvent and/or under solvent-free conditions. The transthioacetalization of oxyacetals into dithioacetals was also achieved in an excellent yield. Copyright © Taylor & Francis Group, LLC  

A novel and smart biopolymer-based hydrogel was synthesized by graft copolymerization of acrylic acid onto the salep backbones. The new superabsorbent hydrogel was synthesized via simultaneous crosslinking and graft copolymerization of acrylic acid (AA) monomer onto salep backbones using radiochemical methods. In radiochemical methods, γ-rays as initiator, energy source and crosslinker are applied. In our experiments, the effects of reaction variables such as relative contents of salep and AA, as well as γ-rays total dose were examined. According to water absorbency of the entitled network, the best synthesis condition is reported. FTIR spectroscopy, SEM photograph and TGA analysis were used... 

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  

KF/Al2O3 efficiently catalyzes N-alkylation of heterocyclic, primary, and secondary amines and S-alkylation of thiols with a variety of alkyl halides. The N-alkylation and S-alkylation adducts were produced in good to excellent yields and in short times. Copyright © Taylor & Francis Group, LLC  

Rapid and efficient condensation reactions of 2-aminothiophenol and 2-aminophenol with various aldehydes were carried out using I2 in solvent-free conditions with or without microwave irradiation to afford the corresponding 2-substituted benzothiazole and benzoxazole derivatives in good to excellent yields. Copyright © Taylor & Francis Group, LLC  

The Taguchi method, a robust experimental design for optimization, was used for the synthesis of a superabsorbent hydrogel network using γ-rays as an initiator, energy source and crosslinker at the same time. Nine different samples of superabsorbent hydrogels were prepared in various conditions from kappa-carrageenan (κC) and acrylamide by γ-irradiation at room temperature. Considering the results of nine trials and according to analysis of variance (ANOVA), a new experimental condition with the concentrations of κC and acrylamide 1.5 g and 0.028 mol (2 g in total volume of 50 mL H2O), respectively, as well as γ-ray at the optimum total dose (7 kGy) was proposed. After preparing the desired...