Sharif Digital Repository

Herein, we report the preparation of novel magnetic graphene oxide (GO) grafted with brush polymer via surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization and its application as a nanocarrier for magnetic- and pH-triggered delivery of doxorubicin anticancer drug. The RAFT agent, DDMAT, was firstly attached to the surface of magnetic GO nanosheets. The DDMAT-functionalized magnetic GO nanosheets were then used to polymerize glycidyl methacrylate (GMA) using an SI-RAFT method. Afterwards, the epoxy rings of the PGMA chains were opened with hydrazine (N2H4) moieties. The resulting nanocomposite was used as a drug carrier for doxorubicin (DOX) as an... 

Electrostatic fiber fabrication technique has evinced more interest and attention in recent years, owing to its versatility, reliability, and potential for applications in diverse fields, particularly separation, extraction, and filtration. The sub-micro fibers are generated by employing strong electric field on polymeric solutions or melt is led to the soft nanometric mats. So far, more than 100 polymers have been Electrospun and this number is gradually increasing. Over recent decades, a remarkable variety of electrospun nanofibers as promising and authentic extracting platforms have been synthesized. They offer various advantages including high surface area-to-volume ratio and tunable... 

In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m-phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR),... 

Magnetic reduced graphene oxide/polymer nanocomposites were prepared by in situ polymerization and grafting of polyacrylamide on the surface of functionalized magnetic reduced graphene oxide (rGO). Graphene oxide nanosheets were decorated with Fe3O4 nanoparticles, reduced and functionalized with 3-(trimethoxysilyl)propyl methacrylate, and then grafted with polyacrylamide. Grafting of polyacrylamide makes magnetic rGO hydrophilic and highly water dispersible. The prepared material was used as adsorbent for removal of an anionic dye, Congo red, and a maximum adsorption capacity up to 166.7 mg g−1 was obtained. The kinetics and isotherm of adsorption and the effect of experimental condition on... 

Herein, we report the preparation of novel magnetic graphene oxide (GO) grafted with brush polymer via surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization and its application as a nanocarrier for magnetic- and pH-triggered delivery of doxorubicin anticancer drug. The RAFT agent, DDMAT, was firstly attached to the surface of magnetic GO nanosheets. The DDMAT-functionalized magnetic GO nanosheets were then used to polymerize glycidyl methacrylate (GMA) using an SI-RAFT method. Afterwards, the epoxy rings of the PGMA chains were opened with hydrazine (N2H4) moieties. The resulting nanocomposite was used as a drug carrier for doxorubicin (DOX) as an... 

Electrostatic fiber fabrication technique has evinced more interest and attention in recent years, owing to its versatility, reliability, and potential for applications in diverse fields, particularly separation, extraction, and filtration. The sub-micro fibers are generated by employing strong electric field on polymeric solutions or melt is led to the soft nanometric mats. So far, more than 100 polymers have been Electrospun and this number is gradually increasing. Over recent decades, a remarkable variety of electrospun nanofibers as promising and authentic extracting platforms have been synthesized. They offer various advantages including high surface area-to-volume ratio and tunable... 

In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m-phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR),... 

The hybrid-polymer nanocomposite poly(styrene-methyl methacrylate- acrylic acid) /nanoclay was synthesized by miniemulsion polymerization for novel use as a drilling fluid additive. Three low-solid-drilling fluids (bentonite-based; natural polymer-based; nanoclay-based) were formulated using the hybrid nanocomposite as an additive and their rheological performance compared. The polymer/clay hybrid nanoparticles significantly improve rheological and filtration properties of the drilling fluids and they remain stable at high pressure, high temperature and harsh salinity conditions. The fluids’ filtration properties improve as the concentration of the polymer/nanoclay-hybrid-nanoparticles... 

The aim of this work is to investigate the effect of molybdenum disulfide on tribological properties of Ultra-high-molecular-weight polyethylene (UHMWPE). UHMWPE/MoS2 nano-composites were prepared using in-situ polymerization and Ziegler-Natta catalytic system. Studies showed that, in order to obtain the optimum tribological properties, interlayer distance between nanosheets should be as high as possible. Therefore, the nanosheets were subjected to oxidation using the required oxidants followed by thermal shock and ultrasound. Fourier-transform infrared spectroscopy (FTIR) analysis was used to determine the formation of functional groups which indicate the formation of S═O bond in the... 

In this study, a new facile and cost effective method is used to modify polysulfone membrane surface in order to improve the hydrophilicity, antifouling, and blood compatibility. This modification was performed by adding two functional monomers on the dialysis membrane. Polysulfone (PSF) membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. In the next step, free radical polymerization combined with surface polymerization was used to introduce acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) onto the polysulfone membrane surface via circulation of initiator and monomer solutions across the membrane surface, respectively. Various monomer concentrations... 

This article reports the synthesis of a magnetic heterogeneous catalyst through the decoration of gold ions onto the cross-linked polymeric nanocomposite from 2,6-diaminopyridine. The activity of the resulting catalyst was then evaluated in the bromination of aromatic compounds. The nitrogen rich support showed a high affinity to gold ions, and the measured content of Au was 0.76 mmol g-1. The structure of the catalyst was fully characterized by using Fourier-transform infrared spectroscopy, thermogravimetric analysis, atomic absorption spectroscopy, transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area... 

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 this study, a new type of magnetite nanocomposite with a core–shell structure was synthesized using Fe3O4 nanoparticles as a core and polyaniline (PANI) as a shell. For this propose, the surface of Fe3O4 was chemically modified with hexamethylenediisocyanate (HMDI) to improve its compatibility and interphase interaction with the polymeric matrix. Thereafter, the PANI was reacted with modified Fe3O4 to anchor them to PANI by covalent bands which acted as a shell. In the second step, the poly (maleic acid-co-acrylic acid) (P(MAc-co-AA)) as polymeric dopant for the PANI was synthesized. Finally, the PANI anchored to Fe3O4 was immersed in an aqueous solution of poly (maleic... 

Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF),... 

In this study, reinforcement of ultra-high molecular weight polyethylene (UHMWPE) was investigated using the sol-gel surface modified diamond nanoparticles (NDs). Nanocomposite samples were synthesized via in-situ polymerization using bi-supported Ziegler-Natta catalyst. Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle measurements proved the proper silanization (∼1.9%) of NDs. Characterization of the catalysts revealed decrease in the activity of catalysts in presence of NDs which were responsible for the lower average molecular weight of the samples. Field emission scanning electron microscopy revealed an improved dispersion of the modified NDs in... 

A new magnetic heterogeneous catalyst was synthesized by immobilization of nickel ions onto a cross-linked polymeric nanocomposite composed of cyanuric chloride, ethylenediamine and functionalized magnetic nanoparticles. The resulting nitrogen rich support was capable of adsorbing large amounts of nickel ions (1.20 mmol g−1). The synthesized catalyst was characterized using AAS, TEM, FT-IR, EDX, TGA, SEM, BET and XRD techniques. The performance of the prepared catalyst was investigated in the C-N coupling of arylamines with aryl boronic acids. The reaction was carried out under a mild condition and good to moderate to good yields of products was obtained using only 5.0 mol% of the catalyst.... 

To compensate for drag increment due to the addition of nanoparticles to heat-transfer fluids, it seems that one could add drag reducer polymeric agents to these fluids. So, in this work, experiments were carried out for solutions of two types of polyacrylamide (FLOPAAM 3330S and FLOPAAM 3630S) at three distinct concentrations (25, 40, and 55 ppm), and TiO2-water nanofluid at concentrations of 0.015, 0.02, 0.025, and 0.03 L/L. The steady state turbulent convective heat transfer and the friction factor of the suspension of TiO2 in a dilute solution of very high molecular weight, polyacrylamide (hybrid fluid), in a coiled tube were analyzed. Experimental measurements were carried out from a... 

In recent years, applications of dielectrophoresis-based platforms have been recognized as effective and dependable approach to separate cells and bioparticles, suspended in different carrier fluids, based on particle size and electrical properties. In this study, a microfluidic device was fabricated by an unprecedented electrode pattern, and several experiments were performed to enrich samples including either of yeast, Escherichia coli, or latex particles. A chemical deposition-based method was employed for fabrication of microelectrodes, inducing nonuniform electric field required for dielectrophoresis-based separation. One major advantage of our employed method is low fabrication cost,... 

An efficient method for the synthesis of functionalized 4H-chromenes via a one-pot three-component condensation reaction of a 2-hydroxybenzaldehyde with an active methylene compound and a carbon-based nucleophile in the presence of a catalytic amount of ZrOCl2·8H2O in water under thermal condition has been described. High yields, simple work-up procedure, performing reactions in water and synthesis of complex molecules with a one-pot procedure are the main advantages of this procedure. In addition, the structure of the product from the condensation of salicylaldehyde, 2-naphthol, and dimedone was confirmed by X-ray crystallography. © 2018 Wiley Periodicals, Inc  

Microfluidic devices are beneficial in miniaturizing and multiplexing various cellular assays in a single platform. Chondrogenesis is known to pertain to chemical, topographical, and mechanical cues in the microenvironment. Mechanical cues themselves have numerous parameters such as strain magnitude, frequency, and stimulation time. Effects of different strain magnitudes on the chondrogenic differentiation of adult stem cells have not been explored thoroughly. Here, a new multilayer microdevice is presented for the unidirectional compressive stimulation of cells in a three-dimensional cell culture. Numerical simulations were performed to evaluate and optimize the design. Results showed a...