Papers by Vahid Haddadi-Asl
Research Square (Research Square), Nov 6, 2023
A novel technique known as water-in-water emulsion was utilized to synthesize the cross-linked na... more A novel technique known as water-in-water emulsion was utilized to synthesize the cross-linked nanoparticles of polydopamine@polyaniline (CPDA@PANI). The synthesized nanoparticles demonstrated their ability to selectively adsorb methyl orange (MO) from aqueous media. Solution pH and contact time are the influential factors employed to ascertain the optimal conditions for organic dye adsorption. Both pseudo-first and pseudo-second-order kinetic models were utilized to fit the adsorption kinetics. Four isothermal adsorption models were used to find the adsorption kinetics model, including Dubnin-Radushkevich, Temkin, Freundlich, and Harkins-Jura. The results revealed that the nanoparticles presented a higher adsorption capacity of 114.48 mgr/gr in acidic medium than in alkaline conditions with dye removal efficiency of 95.4%. This phenomenon can be explained by protonating PANI, which leads to a strong electrostatic attraction between amino and imine groups with MO. By conforming to the pseudo-second-order kinetics model, the adsorption kinetics process displayed a favorable fit, and it was found that the Freundlich isotherm model was more effective for monitoring and assessing adsorption behavior than other available models. It can be derived from this analysis that the absorption of the dye in CPDA@PANI nanoparticles can be categorized as a single-layer adsorption process with homogeneous absorption sites on the nanoparticles.
Research Square (Research Square), Jun 29, 2023
The surface modi cation of halloysite nanotube can make it a very prospering vehicle for cancer d... more The surface modi cation of halloysite nanotube can make it a very prospering vehicle for cancer drug delivery. In the present study, the surface of HNT clay was modi ed with a copolymer of polyacrylic acid (PAA) and polyaniline (PANI). The copolymer was decorated on the surface via a grafting from strategy. To ful ll this, the surface was rstly modi ed with an organosilane component, and then with a chain transfer agent (CTA). Later, the copolymer was grown on the surface via subsequent stages of reversible addition fragmentation chain transfer (RAFT) and oxidative polymerizations. The successful formation of copolymer on HNT surface was corroborated by spectroscopic analyses including FTIR and 1 HNMR. The morphology of the polymer grafted HNT was studied using electron microscopes, i.e. SEM and TEM, and the results revealed that nanostructures with respective mean diameter and length of 40 and 100 nm possessing polymer coating on the interior and exterior surfaces were obtained. The structural analysis with XRD veri ed the crystalline structure of HNT was almost preserved in the presence of copolymer graft and only the interlayer distances were increased. The thermal study via DSC con rmed that the copolymer grafted HNT possessed glass transition, melting, and degradation peaks. And TGA analysis unveiled that HNT grafted with copolymer represented higher thermal stability comparing that one grafted with pristine PAA. Moreover, quantitative results of TGA substantiated that more that 59% copolymer was grafted onto HNT surface. HNT surface was modi ed with a copolymer of polyacrylic acid and polyaniline. Copolymer was decorated on the surface via a grafting from strategy. Copolymer was grown on the surface via RAFT and oxidative polymerizations. Analyses con rmed 59% copolymer was grafted onto HNT surface.
Catalysts, Jan 15, 2021
In this work, the PIL (poly ionic liquid)@TiO 2 composite was designed with two polymerized ionic... more In this work, the PIL (poly ionic liquid)@TiO 2 composite was designed with two polymerized ionic liquid concentrations (low and high) and evaluated for pollutant degradation activity for benzene and toluene. The results showed that PIL (low)@TiO 2 composite was more active than PIL (high)@TiO 2 composites. The photodegradation rate of benzene and toluene pollutants by PIL (low)@TiO 2 and PIL (high)@TiO 2 composites was obtained as 86% and 74%, and 59% and 46%, respectively, under optimized conditions. The bandgap of TiO 2 was markedly lowered (3.2 eV to 2.2 eV) due to the formation of PIL (low)@TiO 2 composite. Besides, graphene oxide (GO) was used to grow the nano-photocatalysts' specific surface area. The as-synthesized PIL (low)@TiO 2 @GO composite showed higher efficiency for benzene and toluene degradation which corresponds to 91% and 83%, respectively. The resultant novel hybrid photocatalyst (PIL@TiO 2 /m-GO) was prepared and appropriately characterized for their microstructural, morphology, and catalytic properties. Among the studied photocatalysts, the PIL (low)@TiO 2 @m-GO composite exhibits the highest activity in the degradation of benzene (97%) and toluene (97%). The ultimate bandgap of the composite reached 2.1 eV. Our results showed that the as-prepared composites hold an essential role for future considerations over organic pollutants.
Journal of Petroleum Science and Technology, Oct 12, 2012
The slurry polymerization of ethylene was studied by employing a (TiCl 4 /Mg(OEt) 2 /TEA) catalys... more The slurry polymerization of ethylene was studied by employing a (TiCl 4 /Mg(OEt) 2 /TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, M v , were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and M v were achieved at 60 °C. The concentration of active sites of the obtained catalyst system for ethylene polymerization was evaluated as a function of Al/Ti molar ratio and polymerization temperature. Increasing Al/Ti molar ratio from 62 to 124 raised the active site concentration of catalyst, [C*], from 0.0003 to 0.0017, whereas a further increase in Al/Ti molar ratio from 124 to 231 reduced [C*] from 0.0017 to 0.0013. Similarly, increasing the temperature from 40 °C to 60 °C increased the [C*] from 0.0002 to 0.0017, but when temperature was increased above the optimum value, [C*] decreased.
Polydopamine is a biomimetic self-adherent polymer, which can be easily deposited on a wide varie... more Polydopamine is a biomimetic self-adherent polymer, which can be easily deposited on a wide variety of materials. Despite the rapidly increasing interest in polydopamine-based coatings, the polymerization mechanism and the key intermediate species formed during the deposition process are still controversial. Herein, we report a systematic investigation of polydopamine formation on halloysite nanotubes; the negative charge and high surface area of halloysite nanotubes favour the capture of intermediates that are involved in polydopamine formation and decelerate the kinetics of the process, to unravel the various polymerization steps. Data from X-ray photoelectron and solid-state nuclear magnetic resonance spectroscopies demonstrate that in the initial stage of polydopamine deposition, oxidative coupling reaction of the dopaminechrome molecules is the main reaction pathway that leads to formation of polycatecholamine oligomers as an intermediate and the post cyclization of the linear ...
The slurry polymerization of ethylene was studied by employing a (TiCl 4 /Mg(OEt) 2 /TEA) catalys... more The slurry polymerization of ethylene was studied by employing a (TiCl 4 /Mg(OEt) 2 /TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, M v , were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and M v were achieved at 60 °C. The concentration of active sites of the obtained catalyst system for ethylene polymerization was evaluated as a function of Al/Ti molar ratio and polymerization temperature. Increasing Al/Ti molar ratio from 62 to 124 raised the active site concentration of catalyst, [C*], from 0.0003 to 0.0017, whereas a further increase in Al/Ti molar ratio from 124 to 231 reduced [C*] from 0.0017 to 0.0013. Similarly, increasing the temperature from 40 °C to 60 °C increased the [C*] from 0.0002 to 0.0017, but when temperature was increased above the optimum value, [C*] decreased.
Photodiagnosis and Photodynamic Therapy, 2021
Background: In this study, the ability of antimicrobial photodynamic therapy (aPDT) as a treatmen... more Background: In this study, the ability of antimicrobial photodynamic therapy (aPDT) as a treatment approach and adjuvant therapy using curcumin-poly (lactic-co-glycolic acid) nanoparticles (Cur@PLGA-NPs) to inactivate Coronavirus disease 2019 (COVID-19) in plasma was investigated. Furthermore, to verify whether the quality requirement of aPDT-treated plasma is acceptable, the differences of the levels of clotting factors, total plasma proteins, and anti-A and/or anti-B antibodies titrations in plasma of patient before and after aPDT treatment were investigated. Materials and Methods: Cur@PLGA-NPs was synthesized using Electrospinning process and characterized by different analysis including Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and Fourier Transform Infrared (FTIR) spectroscopy assays. The presence of the SARS-CoV-2 in the plasma samples of patients suspected of having COVID-19 was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR) assay. Then, the treated plasma samples with Cur@PLGA-NPs plus blue laser were exposed to Vero cells. Eventually, cell cytotoxicity and apoptotic effects of treated Vero cells were evaluated. Levels of clotting factors including prothrombin time (PT) and activated partial thromboplastin time (APTT), total plasma proteins, and anti-A and/or anti-B antibodies measurements were performed using the coagulometer, method of Bradford, and titration procedure, respectively. Results: The presence of SARS-CoV-2 was positive in 84.3 % of samples. Different concentrations of Cur@PLGA-NPs (3, 5, 7, and 10 % wt.), the irradiation times of blue laser (1, 3, and 5 min), and aPDT with the maximum dosed of blue laser light (522.8 J/cm 2 ) plus 10 % wt. Cur@PLGA-NPs had no cytotoxicity. Although there were significant cell degradation and apoptotic effects in treated Vero cells with treated plasma using 10 % wt. Cur@PLGA-NPs, and a blue laser at an energy density of 522.8 J/cm 2 , no visible changes in cells and apoptosis were observed following aPDT. Total plasma protein content, PT, APTT, and anti-A and/or anti-B antibodies titers showed no significant changes (P > 0.05 for all comparisons) in treated plasma as compared to untreated plasma. Conclusion: aPDT exhibited in vitro anti-COVID-19 activities in the treated plasma containing SARS-COV-2 without Vero cell apoptosis and any adverse effects on plasma quality in aPDT-exposed plasma.
Applied Surface Science, 2020
Fluorination of graphene has multitude merits owing to the peculiar temperament of the carbon-flu... more Fluorination of graphene has multitude merits owing to the peculiar temperament of the carbon-fluorine (C-F) bond. the Current synthesis modalities of fluorinated graphene (FG) is based on the usage of toxic materials at high temperature, which is problematic to be used. The methods to overcome these problems is challenging for chemists. Ionic liquids (ILs) have been used in several chemical processes as auxiliaries and eco-friendly alternative instead of volatile organic solvents (VOS) because of their properties. Consequently, herein we exploited a highly effective and green process for the synthesis of FG at mild temperature (80 °C), by using ammonium fluoride salt as fluorine agent, and a synthesized acidic IL ([TEA]+[TFA]-) as catalyst and co-solvent. Our goal was synthesis enriched FG with a high degree of fluorination (70.4 wt.% of F) and F/C ratio (2.4), which measured and confirmed by XPS analysis. Subsequently, the obtained FG was used as a nanocarrier for delivery of curcumin (Cur-a natural antitumor drug) to cancerous cells. The in-vitro results showed that these nanosheets possessed a higher Cur-loading efficiency (78.43%) when compared to FG that was purchased from industry (52.12%). This, in turn, translated into in-vitro anti-cancer effect when tested against cancerous cells (PC-3 cells).
Materials Research Express, 2019
In this work, morphological, phase transitions, microphase separation, hydrogen bonding, rheologi... more In this work, morphological, phase transitions, microphase separation, hydrogen bonding, rheological and mechanical properties of novel thermoplastic polyurethane elastomers (TPUs) consisting of polytetrahydrofuran/ polycaprolactone (PTHF/PCL) as soft segments with different soft segment arrangements were discussed. Change in sequence of feeding as a reliable method for controlling soft segment arrangements was developed. Successful synthesizing of the TPUs was evaluated by ATR-FTIR and 13C NMR spectroscopy. AFM images indicated that the change in soft segment arrangements of TPUs with same molar ratio of ingredients led to different hard segment aggregations morphology. Time sweep experiment showed that the storage modulus evolution at 125 °C is different with 140 °C, and kinetics and extent of microphase separation was systematically found to reduce with increasing temperature. Isothermal and non-isothermal examinations have shown that using PCL and PTHF in the main chain accelerates the microphase separation process comparing sample with blend of polyurethanes containing one type of polyols. Mechanical property data indicated that the extreme enhanced elongation at break and toughness of TPU with random soft segment arrangements of PTHF/PCL is highest in comparison with other samples.
Polymer Composites, 2018
The multiwalled carbon nanotubes (MWCNTs), Closite 30B nanoplates (CBNPs), and halloysite nanotub... more The multiwalled carbon nanotubes (MWCNTs), Closite 30B nanoplates (CBNPs), and halloysite nanotubes (HNTs) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared via melt compounding method and evaluated with several techniques including microscopy, spectroscopy, thermal, and rheological analyses. Degree of microphase separation and nucleation efficiency of nanocomposites were calculated. Results showed that at 0.1 wt% nanofiller content, the nanocomposites possess the fastest microphase separation kinetics and the highest degree of microphase separation. Avrami equation was used to analyze the crystallization behavior of samples. Based on the rheological and microscopy analyses, existence of microphase separation above the percolation threshold was observed for annealed samples. Finally, competition between reagglomeration of nanofillers and formation of microphase separated domains above the percolation threshold at various nanofiller contents, shear rates and te...
Artificial Cells, Nanomedicine, and Biotechnology, 2016
Hybrid scaffolds prepared by blend electrospinning of Polycaprolactone and Pluronic solution bene... more Hybrid scaffolds prepared by blend electrospinning of Polycaprolactone and Pluronic solution benefit from enhanced fiber hydrophilicity and may offer satisfactory cell attachment and proliferation. To improve hybrid scaffold wettability and water swelling ratio, adequate amount of hydrophilic polymer is required; though this amount is limited by fiber surface enrichment of Pluronic and cannot be exceeded without affecting the scaffold mechanical properties. To overcome this problem, a routine blend electrospinning setup was modified by exposing the blend solution to water in order to attract Pluronic chains toward the surface of the charged jet. Morphology of scaffolds produced by the routine blend electrospinning and modified method was studied. A 50 nm thick Pluronic layer with linty appearance on the surface of the fibers fabricated by the modified method was detected. Drug-loaded fibers from modified method showed a moderate initial burst and then a prolonged release period while an abnormal twostage phased release profile was observed for the routine blend method. The latter was associated to Pluronic/drug accumulations within the fibers fabricated by the routine method which resulted in fiber disintegration and a subsequent second burst release.
A composite membrane from a single sheet of Daramic, a macroporous separator, Is prepared by inco... more A composite membrane from a single sheet of Daramic, a macroporous separator, Is prepared by incorporation of an anion exchange resin, Amberlite CG 400, and further cross-linking with dvinylbenzene [1] . Further modification and characterization of the composite membrane are now described. A detailed FESEM, TGA, FT-IR and 13C NMR analyses of the composite membrane have been carried out. The ion exchange capacity of the composite membrane has been also evaluated . Formation of thin layer of polydivinylbenzene after cross-Ilnklng Is confirmed .by morphological studies. None of the experiments show incorporation of the ion exchange resin Into the composite membrane.
ynthesis of polyethylene terephthalate (PET) in laboratory is a challenging task due to high reac... more ynthesis of polyethylene terephthalate (PET) in laboratory is a challenging task due to high reaction temperature up to 280ºC and high pressure in esterification step and low vacuum in polycondensation step. In this research, synthesis of PET, in a laboratory size unit was studied via direct esterification of terephthalic acid and ethylene glycol. Antimony oxide was added as catalyst for polycondensation. Mathematical model of process is presented based on the mass balance of different species such as acid and hydroxyl end groups, water output, diester groups during both esterification and polycondensation steps. Derived governing equations were integrated numerically using Runge-Kutta method. Reacting mixture mass variation was included in the model. Comparison of experimental and simulation results shows promising and good agreement. Hence, the model could be used as a powerful tool for engineering process. The model was applied to study different aspects of polymerization process.
Iranian Polymer Journal, 2013
In this work, a new simple and robust method for preparation of polymer-grafted inorganic hybrids... more In this work, a new simple and robust method for preparation of polymer-grafted inorganic hybrids through ''grafting to'' reaction is presented. Polymer chains were synthesized by reversible chain transfer catalyzed polymerization (RTCP) are capped with iodine according to the RTCP mechanism. The obtained iodine-capped polymer chains can react irreversibly with the hydroxyl groups available on the surface of inorganic materials through a nucleophilic substitution (SN) reaction. In this method, there is no need to modify the surface of inorganic materials or to functionalize polymer chains prior to the ''grafting to'' reaction. RTCP produced polystyrenes with different molecular weights, e.g., 4,000, 6,000, and 8,000 g/mol, and silica nanoparticles were employed as the polymer and inorganic materials, respectively. The resulting hybrids were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, and transmission electron microscopy techniques. According to the results, graft density decreased by increasing the polystyrene molecular weight. Additionally, the rheological studies of prepared polystyrene nanocomposites containing 2 wt % of the produced hybrids confirmed the better dispersion of the modified hybrids in the polystyrene matrix. The glass transition temperature (T g ) of the polystyrene nanocomposites was driven by differential scanning calorimeter technique. Analysis of nanocomposites' T g results revealed that increment of the grafted polymer molecular weight of hybrids increased the glass transition temperature of the prepared nanocomposites due to improvement of the dispersion level.
e-Polymers, 2007
Precipitation polymerization method is a non homogeneous method in which polymer chains are separ... more Precipitation polymerization method is a non homogeneous method in which polymer chains are separated from continuous phase as polymer particles. In this method, all polymerization reactions occur in continuous and polymer dispersed phases based on simultaneous polymerization theory. Hunkeler theory is a perfect "simultaneous polymerization" theory that predicts molecular weights and the rate of polymerization for precipitation polymerization of hydrophilic monomers. In this paper, finite moment method is used to predict features of precipitation polymerization. This model is able to predict number and weight average degree of polymerization in dispersed and continuous phases, polydispersity index (PDI) for two phases and volume fraction of primary and secondary particles. Experimental results are in agreement with the properties of dispersed phase; weight and number average degree of polymerization in the dispersed phase is more than that of degrees of polymerization in t...
Iranian Polymer Journal, 2009
recipitation polymerization is a non-homogeneous free radical polymerization method in which poly... more recipitation polymerization is a non-homogeneous free radical polymerization method in which polymer chains are separated from continuous phase as polymer particles. In this method, all polymerization reactions occur in continuous phase as well as in polymer dispersed phase. We found that the initial concentrations of initiator and monomer are determining factors in polymerization behaviour. Unlike the other free radical polymerization methods, termination by precipitation induces the formation of polymer chains with similar chain length to take over bimolecular termination. Thus, the number-and weight-average degree of polymerization depends slightly on the reaction time. In this work, the yield of reaction was measured using a gravimetric method. The yield of reaction and number-and weight-average degree of polymerization of polymer particles were found to be dependent on the non-solvent type and purification process. When the solubility parameter differences of non-solvent and polymer decrease, the yield of reaction dropps but the M n and M w tended to increase. The purification process affected the yield of reaction and molecular weights through the oligomer sedimentation. We concluded that polydispersity index (PDI) of precipitation polymerization is lower than that of the free radical homogeneous and heterogeneous polymerization methods.
IRANIAN POLYMER …, 2011
Although reversible addition-fragmentation chain transfer (RAFT) polymerization has attracted gre... more Although reversible addition-fragmentation chain transfer (RAFT) polymerization has attracted great attention of many researchers over recent years, outstanding questions on the mechanism and kinetics of dithioester-mediated RAFT polymerization (especially ...
Communications in Soil Science and Plant Analysis, 1995
ABSTRACT: Controlled release urea fertilizers based on N,N'-methylene bis-acrylamide (NNMBA)... more ABSTRACT: Controlled release urea fertilizers based on N,N'-methylene bis-acrylamide (NNMBA)-crosslinked polyacrylamide soil conditioner are described. Laboratory preparation and evaluation of coated urea fertilizers were conducted. Urea was initially coated with ...
Cells Tissues Organs, 2009
Tissue engineering of implantable cellular constructs is an emerging cellular therapy for hepatic... more Tissue engineering of implantable cellular constructs is an emerging cellular therapy for hepatic disease. In this study, we tested the ability of poly(ε-caprolactone) (PCL) nanofiber scaffold to support and maintain hepatic differentiation of human cord blood-derived unrestricted somatic stem cells (USSCs) in vitro. USSCs, self-renewing pluripotent cells, were isolated from human cord blood. The electrospun PCL nanofiber porous scaffold was constructed of uniform, randomly oriented nanofibers. USSCs were seeded onto PCL nanofiber scaffolds, and were induced to differentiate into hepatogenic lineages by culturing with differentiation factors for 6 weeks. RT-PCR analysis of endoderm and hepatic-specific gene expression, immunohistochemical detection of cytokeratin 18 (CK-18), α-fetoprotein, albumin, glycogen storage and indocyanine green uptake confirmed the differentiation of USSCs into endoderm and hepatocyte-like cells. In the present study, we show that hepatocyte-like cells diff...
Iranian Polymer Journal(Iran), 1996
Conductive polymer composite materials are fabricated by mixing high density polyethylene or poly... more Conductive polymer composite materials are fabricated by mixing high density polyethylene or polypropylene with conductive fillers . To overcome the deterioration in mechanical properties of carbon-polymer composites with high carbon loading, ethylene-propylene rubber is blended into the composites . The electrical and mechanical properties of the composite materials are studied . Because blending of polymeric phase with conductive particles influences the morphology which in turn affects the performance of the final composite, the morphology and microstructure of the blends and that of the composites are examined as well ..
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Papers by Vahid Haddadi-Asl