Nasser Nikfarjam - Academia.edu (original) (raw)
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Papers by Nasser Nikfarjam
Colloid and Polymer Science, 2014
Here, we present a method to synthesize expandable spherical polystyrene beads containing well-di... more Here, we present a method to synthesize expandable spherical polystyrene beads containing well-dispersed water microdroplets. The beads, 2-3 mm in diameter, were prepared through surfactant-free Pickering emulsion polymerization in water-in-oil-in-water (w/o/w) system using crosslinked starch nanoparticles (CSTN) as emulsifier. The CSTNs were in situ surface-modified by styrene maleic anhydride copolymer as confirmed by infrared spectroscopy and contact angle analysis. The entrapped water microdroplets with the average size of 3-4 μm were shown to be surrounded by a dense layer of the CSTN. The number droplet density as well as water encapsulation efficiency in the polystyrene beads increased with the CSTN concentration. Furthermore, regardless of CSTN content, all samples exhibited high encapsulation stability of over 68 % after 3 months. These characteristics along with good expansion behavior suggest the synthesized beads as expandable polystyrene containing water as a green blowing agent.
Applied Organometallic Chemistry
ACS Omega
A macroporous dual-functional acid−base covalent organic polymer catalyst poly(St-VBC)-NH 2-SO 3 ... more A macroporous dual-functional acid−base covalent organic polymer catalyst poly(St-VBC)-NH 2-SO 3 H was prepared using high internal phase emulsion polymerization using vinylbenzyl chloride (VBC), styrene (St), and divinylbenzene (DVB) as substrates toluene as a porogenic solvent, and subsequent modification with ethylenediamine and 1,3-propane sultone. The role of various amounts of toluene as the porogenic solvent as well as the amount of 1,3-propane sultone (different ratio of acid/base sites) on the structure of the prepared materials have been carefully investigated. The prepared materials were characterized by Fourier transform infrared (FT-IR), CHNS elemental analysis, energydispersive X-ray (EDX), elemental mapping, field emission scanning electron microscopy (FE-SEM), and thermalgravimetric analysis (TGA). The catalytic activity of the poly(St-VBC)-NH 2-SO 3 H series with different acid/base densities was assessed for onepot cascade C−C bond-forming reactions involving deacetylation−Henry reactions. The poly(St-VBC)-NH 2-SO 3 H(20) sample bearing 1.82 mmol/g of N (base site) and 1.16 mmol/g (acid site) showed the best catalytic activity. The catalyst demonstrated superior activity compared to the homogeneous catalysts, poly(St-DVB)-SO 3 H+EDA, poly(St-VBC)-NH 2 +chlorosulfonic acid, and poly(St-DVB)-SO 3 H+poly(St-VBC)-NH 2 as the catalyst system. The optimized catalyst showed excellent catalytic performance with 100% substrate conversion and 100% yield of the final product in the one-pot production of β-nitrostyrene from benzaldehyde dimethyl acetal under cascade reactions comprising acid-catalyzed deacetalization and base-catalyzed Henry reactions. It was shown that these catalysts were reusable for up to four consecutive runs with a very slight loss of activity. The excellent performance of the catalyst was attributed to the excellent chemical and physical properties of the developed support since it provides an elegant route for preparing site-isolated acid−base dual heterogenized functional groups and preventing their deactivation via chemical neutralization.
ACS Chemical Neuroscience
RSC Advances
The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrog... more The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrogel-based tissue scaffolds to biomimic a natural extracellular matrix for cell growth.
RSC Advances, 2022
PFPS nanosheets modulate the amyloid fibrillation of HEWL much more effective than the bulk form ... more PFPS nanosheets modulate the amyloid fibrillation of HEWL much more effective than the bulk form of PFPS. Based on the thioflavin T results, a delay in the initiation of the assembly process appears to be the mechanism of action of PFPS nanosheets.
Journal of Cellular Physiology, 2020
Controlled‐release drug delivery systems are promising platforms in medicine. Among various types... more Controlled‐release drug delivery systems are promising platforms in medicine. Among various types of material in drug delivery, hydrogels are interesting ones. They are water‐soluble and tissue compatible polymers with a high capacity to carry and release drugs in a controllable manner. In this study, we introduce the synthesis, characterization, and application of an α‐amylase responsive hydrogel in controlled drug delivery. The newly synthesized starch‐based hydrogels structurally characterized by means of Fourier‐transform infrared spectroscopy and scanning electron microscopy. A proapoptotic drug, doxorubicin, was loaded into the hydrogels and the controlled release of the drug was assessed in the presence of α‐amylase and ultimately it was evaluated to controlled‐drug release in vitro and subsequently in killing cancer cells. Our results highlight the effectiveness of temporal drug delivery using α‐amylase responsive hydrogels in killing cancer cells.
Polymer-Plastics Technology and Engineering, 2013
ABSTRACT The nanocomposites of HDPE/PA6 and HDPE-g-MAH/PA6 in the presence of two types of 30B an... more ABSTRACT The nanocomposites of HDPE/PA6 and HDPE-g-MAH/PA6 in the presence of two types of 30B and 15A organoclays (Oclay) were prepared via melt compounding. The XRD and TEM results confirmed the nanoscale morphology obtained by the nanoparticles. HDPE-g-MAH/PA6 samples, due to the compatibility between the phases, indicated better morphology, higher viscosity and better barrier properties than HDPE/PA6 samples. In contrast, the presence of polyethylene led to the higher modulus, crystalinity and thermal stability of HDPE/PA6 samples. 15A nanoparticles caused better performance in the properties than other particles and specially a perceptible increase in the melt viscosity and barrier properties of HDPE-g-MAH/PA6 blend.
Colloid and Polymer Science, 2013
Here, we present a method to synthesize expandable spherical polystyrene beads containing well-di... more Here, we present a method to synthesize expandable spherical polystyrene beads containing well-dispersed water microdroplets. The beads, 2-3 mm in diameter, were prepared through surfactant-free Pickering emulsion polymerization in water-in-oil-in-water (w/o/w) system using crosslinked starch nanoparticles (CSTN) as emulsifier. The CSTNs were in situ surface-modified by styrene maleic anhydride copolymer as confirmed by infrared spectroscopy and contact angle analysis. The entrapped water microdroplets with the average size of 3-4 μm were shown to be surrounded by a dense layer of the CSTN. The number droplet density as well as water encapsulation efficiency in the polystyrene beads increased with the CSTN concentration. Furthermore, regardless of CSTN content, all samples exhibited high encapsulation stability of over 68 % after 3 months. These characteristics along with good expansion behavior suggest the synthesized beads as expandable polystyrene containing water as a green blowing agent.
Advanced Functional Materials
In situ bromination of vinyl monomers with tetra-n-butyl ammonium tribromide and irradiation of t... more In situ bromination of vinyl monomers with tetra-n-butyl ammonium tribromide and irradiation of the corresponding dibromide upon exposure to visible-LED (λ=400 nm) followed by C-Br bond photocleavage, successfully synthesis of polystyrene, polyacrylamide and the related random and block compolymers. GPC data revealed relatively low distributions in molecular weight for Dibromide-synthesized homo/copolymers, comparable with data obtained for ATRP, photo-ATRP and metal-free photo-ATRP.
Polymer International, 2016
Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nan... more Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nanoplatelets into poly(vinyl acetate) (PVAc) through the simple solvent mixing method. TEM and XRD revealed that well exfoliated graphene nanoplatelets formed a continuous network throughout the matrix with a large amount of interconnectedness. Dynamic mechanical analysis showed that the inclusion of graphene significantly improves both glassy and rubbery moduli of the matrix. Furthermore, the prepared nanocomposites demonstrated a marked electrical conductivity up to 24.7 S m−1 and thereby surprisingly rapid electrical actuation behaviour exhibiting a 100% recovery ratio in 2.5 s. Moreover, PVAc and its nanocomposites displayed scratch self-healing capability. This work demonstrates that the PVAc/graphene nanocomposites with high modulus and excellent electroactive shape memory performance can be a promising material in many applications such as sensors and fast deployable and actuating devices. © 2016 Society of Chemical Industry
Chemical and Biological Technologies in Agriculture
Background Tribenuron-methyl is a registered herbicide for broad-leaf weed control in wheat, howe... more Background Tribenuron-methyl is a registered herbicide for broad-leaf weed control in wheat, however, low solubility in water and reacting with hard water's ions could substantially decrease its efficacy. The present work aimed to enhance the dispersing and bioactivity of this herbicide by developing nanoparticles using zein as a promising nano-delivery system and to assess the effects of nanoparticles on the efficacy of tribenuron-methyl in the suppression of Convolvulus arvensis as a problematic weed in wheat fields. Results Based on SEM analyses nanoparticles sizes were 80–120 nm. DLS results showed an average size of 170 nm for tribenuron-methyl zein-based nanoparticles (TMZNP-5). The entrapment efficiency (EE%) of tribenuron-methyl inside the zein nanoparticles was ca. 81% ± 3. Five-week after application of tribenuron-methyl nanoparticles on C. arvensis, it was able to reduce the dry weight (53%), acetolactate synthase (ALS) enzyme activity (82%), and plant height (77%) of...
Journal of Molecular Liquids
ACS Applied Bio Materials
Advanced Functional Materials
Industrial & Engineering Chemistry Research
Colloid and Polymer Science, 2014
Here, we present a method to synthesize expandable spherical polystyrene beads containing well-di... more Here, we present a method to synthesize expandable spherical polystyrene beads containing well-dispersed water microdroplets. The beads, 2-3 mm in diameter, were prepared through surfactant-free Pickering emulsion polymerization in water-in-oil-in-water (w/o/w) system using crosslinked starch nanoparticles (CSTN) as emulsifier. The CSTNs were in situ surface-modified by styrene maleic anhydride copolymer as confirmed by infrared spectroscopy and contact angle analysis. The entrapped water microdroplets with the average size of 3-4 μm were shown to be surrounded by a dense layer of the CSTN. The number droplet density as well as water encapsulation efficiency in the polystyrene beads increased with the CSTN concentration. Furthermore, regardless of CSTN content, all samples exhibited high encapsulation stability of over 68 % after 3 months. These characteristics along with good expansion behavior suggest the synthesized beads as expandable polystyrene containing water as a green blowing agent.
Applied Organometallic Chemistry
ACS Omega
A macroporous dual-functional acid−base covalent organic polymer catalyst poly(St-VBC)-NH 2-SO 3 ... more A macroporous dual-functional acid−base covalent organic polymer catalyst poly(St-VBC)-NH 2-SO 3 H was prepared using high internal phase emulsion polymerization using vinylbenzyl chloride (VBC), styrene (St), and divinylbenzene (DVB) as substrates toluene as a porogenic solvent, and subsequent modification with ethylenediamine and 1,3-propane sultone. The role of various amounts of toluene as the porogenic solvent as well as the amount of 1,3-propane sultone (different ratio of acid/base sites) on the structure of the prepared materials have been carefully investigated. The prepared materials were characterized by Fourier transform infrared (FT-IR), CHNS elemental analysis, energydispersive X-ray (EDX), elemental mapping, field emission scanning electron microscopy (FE-SEM), and thermalgravimetric analysis (TGA). The catalytic activity of the poly(St-VBC)-NH 2-SO 3 H series with different acid/base densities was assessed for onepot cascade C−C bond-forming reactions involving deacetylation−Henry reactions. The poly(St-VBC)-NH 2-SO 3 H(20) sample bearing 1.82 mmol/g of N (base site) and 1.16 mmol/g (acid site) showed the best catalytic activity. The catalyst demonstrated superior activity compared to the homogeneous catalysts, poly(St-DVB)-SO 3 H+EDA, poly(St-VBC)-NH 2 +chlorosulfonic acid, and poly(St-DVB)-SO 3 H+poly(St-VBC)-NH 2 as the catalyst system. The optimized catalyst showed excellent catalytic performance with 100% substrate conversion and 100% yield of the final product in the one-pot production of β-nitrostyrene from benzaldehyde dimethyl acetal under cascade reactions comprising acid-catalyzed deacetalization and base-catalyzed Henry reactions. It was shown that these catalysts were reusable for up to four consecutive runs with a very slight loss of activity. The excellent performance of the catalyst was attributed to the excellent chemical and physical properties of the developed support since it provides an elegant route for preparing site-isolated acid−base dual heterogenized functional groups and preventing their deactivation via chemical neutralization.
ACS Chemical Neuroscience
RSC Advances
The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrog... more The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrogel-based tissue scaffolds to biomimic a natural extracellular matrix for cell growth.
RSC Advances, 2022
PFPS nanosheets modulate the amyloid fibrillation of HEWL much more effective than the bulk form ... more PFPS nanosheets modulate the amyloid fibrillation of HEWL much more effective than the bulk form of PFPS. Based on the thioflavin T results, a delay in the initiation of the assembly process appears to be the mechanism of action of PFPS nanosheets.
Journal of Cellular Physiology, 2020
Controlled‐release drug delivery systems are promising platforms in medicine. Among various types... more Controlled‐release drug delivery systems are promising platforms in medicine. Among various types of material in drug delivery, hydrogels are interesting ones. They are water‐soluble and tissue compatible polymers with a high capacity to carry and release drugs in a controllable manner. In this study, we introduce the synthesis, characterization, and application of an α‐amylase responsive hydrogel in controlled drug delivery. The newly synthesized starch‐based hydrogels structurally characterized by means of Fourier‐transform infrared spectroscopy and scanning electron microscopy. A proapoptotic drug, doxorubicin, was loaded into the hydrogels and the controlled release of the drug was assessed in the presence of α‐amylase and ultimately it was evaluated to controlled‐drug release in vitro and subsequently in killing cancer cells. Our results highlight the effectiveness of temporal drug delivery using α‐amylase responsive hydrogels in killing cancer cells.
Polymer-Plastics Technology and Engineering, 2013
ABSTRACT The nanocomposites of HDPE/PA6 and HDPE-g-MAH/PA6 in the presence of two types of 30B an... more ABSTRACT The nanocomposites of HDPE/PA6 and HDPE-g-MAH/PA6 in the presence of two types of 30B and 15A organoclays (Oclay) were prepared via melt compounding. The XRD and TEM results confirmed the nanoscale morphology obtained by the nanoparticles. HDPE-g-MAH/PA6 samples, due to the compatibility between the phases, indicated better morphology, higher viscosity and better barrier properties than HDPE/PA6 samples. In contrast, the presence of polyethylene led to the higher modulus, crystalinity and thermal stability of HDPE/PA6 samples. 15A nanoparticles caused better performance in the properties than other particles and specially a perceptible increase in the melt viscosity and barrier properties of HDPE-g-MAH/PA6 blend.
Colloid and Polymer Science, 2013
Here, we present a method to synthesize expandable spherical polystyrene beads containing well-di... more Here, we present a method to synthesize expandable spherical polystyrene beads containing well-dispersed water microdroplets. The beads, 2-3 mm in diameter, were prepared through surfactant-free Pickering emulsion polymerization in water-in-oil-in-water (w/o/w) system using crosslinked starch nanoparticles (CSTN) as emulsifier. The CSTNs were in situ surface-modified by styrene maleic anhydride copolymer as confirmed by infrared spectroscopy and contact angle analysis. The entrapped water microdroplets with the average size of 3-4 μm were shown to be surrounded by a dense layer of the CSTN. The number droplet density as well as water encapsulation efficiency in the polystyrene beads increased with the CSTN concentration. Furthermore, regardless of CSTN content, all samples exhibited high encapsulation stability of over 68 % after 3 months. These characteristics along with good expansion behavior suggest the synthesized beads as expandable polystyrene containing water as a green blowing agent.
Advanced Functional Materials
In situ bromination of vinyl monomers with tetra-n-butyl ammonium tribromide and irradiation of t... more In situ bromination of vinyl monomers with tetra-n-butyl ammonium tribromide and irradiation of the corresponding dibromide upon exposure to visible-LED (λ=400 nm) followed by C-Br bond photocleavage, successfully synthesis of polystyrene, polyacrylamide and the related random and block compolymers. GPC data revealed relatively low distributions in molecular weight for Dibromide-synthesized homo/copolymers, comparable with data obtained for ATRP, photo-ATRP and metal-free photo-ATRP.
Polymer International, 2016
Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nan... more Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nanoplatelets into poly(vinyl acetate) (PVAc) through the simple solvent mixing method. TEM and XRD revealed that well exfoliated graphene nanoplatelets formed a continuous network throughout the matrix with a large amount of interconnectedness. Dynamic mechanical analysis showed that the inclusion of graphene significantly improves both glassy and rubbery moduli of the matrix. Furthermore, the prepared nanocomposites demonstrated a marked electrical conductivity up to 24.7 S m−1 and thereby surprisingly rapid electrical actuation behaviour exhibiting a 100% recovery ratio in 2.5 s. Moreover, PVAc and its nanocomposites displayed scratch self-healing capability. This work demonstrates that the PVAc/graphene nanocomposites with high modulus and excellent electroactive shape memory performance can be a promising material in many applications such as sensors and fast deployable and actuating devices. © 2016 Society of Chemical Industry
Chemical and Biological Technologies in Agriculture
Background Tribenuron-methyl is a registered herbicide for broad-leaf weed control in wheat, howe... more Background Tribenuron-methyl is a registered herbicide for broad-leaf weed control in wheat, however, low solubility in water and reacting with hard water's ions could substantially decrease its efficacy. The present work aimed to enhance the dispersing and bioactivity of this herbicide by developing nanoparticles using zein as a promising nano-delivery system and to assess the effects of nanoparticles on the efficacy of tribenuron-methyl in the suppression of Convolvulus arvensis as a problematic weed in wheat fields. Results Based on SEM analyses nanoparticles sizes were 80–120 nm. DLS results showed an average size of 170 nm for tribenuron-methyl zein-based nanoparticles (TMZNP-5). The entrapment efficiency (EE%) of tribenuron-methyl inside the zein nanoparticles was ca. 81% ± 3. Five-week after application of tribenuron-methyl nanoparticles on C. arvensis, it was able to reduce the dry weight (53%), acetolactate synthase (ALS) enzyme activity (82%), and plant height (77%) of...
Journal of Molecular Liquids
ACS Applied Bio Materials
Advanced Functional Materials
Industrial & Engineering Chemistry Research