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مرکز اطلاعات علمی SID1
مرکز اطلاعات علمی SID
اسکوپوس
مرکز اطلاعات علمی SID
ریسرچگیت
strs
نشریه: 

نانوساختارها

اطلاعات دوره: 
  • سال: 

    1395
  • دوره: 

    6
  • شماره: 

    1
  • صفحات: 

    35-42
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    161
  • دانلود: 

    20
چکیده: 

در این مقاله نانوذرات تیتانیوم دی اکسید کپسوله شده با استایرن سنتز شد. استایرن بوسیله پلیمریزاسیون رادیکالی با کمک نیتروکسید در حضور 3-آمینوپروپیل تری اتوکسی سیلان (APTES) به عنوان عامل اتصال با نانوذرات تیتانیوم دی اکسید متصل شد. آغازگر پلیمریزاسیون TEMPO می باشد. ابتدا آغازگر با روش جدید با سطح نانوذرات تیتانیوم دی اکسید پیونو کووالانسی می دهد. برای این کار، ابتدا سطح نانوذرات با APTES عامل دار می شود و سپس با کلروفنیل استیل کلرید وارد واکنش می شود. گروه های کلر بوسیله TEMPO-OH به نیتروکسید تبدیل می شوند و سپس نانوذرات بهبودیافته داخل مونومر استایرن جهت پلیمریاسیون رادیکالی پخش می شوند.

آمار یکساله:  

بازدید 161

دانلود 20 استناد 0 مرجع 0
اطلاعات دوره: 
  • سال: 

    2012
  • دوره: 

    21
  • شماره: 

    10
  • صفحات: 

    661-668
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    11104
  • دانلود: 

    9195
کلیدواژه: 
چکیده: 

Sulfonated polymer/silica hybrid nanoparticles were prepared by free radical polymerization of 2-acrylamido-2-methyl-1-propane sulfonic acid (PAMPS-g-SN) and styrene sulfonic acid sodium salt (PSSA-g-SN), initiated on the surfaces of amino propyl-functionalized silica nanoparticles (ASN). Ce (IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer, respectively. ASN Nanoparticles were synthesized by a covalently attached 3-aminopropyltriethoxysilane onto the surface of silica nanoparticles. Sulfonated monomers (AMPS or SSA) were then grafted onto the ASN nanoparticles, ultrasonically dispersed in water, using redox initiator system at 40°C. ASN, PAMPS-g-SN and PSSA-g-SN nanoparticles were characterized by Fourier transform infrared (FTIR), thermogravimetry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. FTIR and TGA results indicated that both AMPS and SSA monomers were successfully grafted onto the silica nanoparticles. The grafted amounts of sulfonated polymers onto the silica nanoparticles were estimated from TGA thermo grams to be 46 and 22 % for PAMPS and PSSA, respectively. From SEM and TEM micrographs, the average-diameters of the polymer-grafted silica nanoparticles were measured to be < 50 nm with a (semi) spherical morphology, in which several silica nanoparticles were able to form a core with PAMPS or PSSA existing around the silica nanoparticles.

آمار یکساله:  

بازدید 11104

دانلود 9195 استناد 0 مرجع 0
اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    0
  • شماره: 

    11
تعامل: 
  • بازدید: 

    1155
  • دانلود: 

    0
چکیده: 

HYDROXYAPATITE NANOPARTICLES ARE USED WIDELY IN BONE REPLACEMENT AND TISSUE ENGINEERING. surface-initiated ATRP ON HA PARTICLES USING DMAEMA MONOMERS IS CARRIED OUT IN THIS WORK IN ORDER TO OBTAIN OPTIMUM MECHANICAL PROPERTIES IN THE RESULTANT POLYMER-MATRIX COMPOSITE. FIRST, NH2-HA PARTICLES ARE SYNTHESIZED USING APTES, AND THEN INITIATOR-FUNCTIONALIZED HA PARTICLES, BR-HA, ARE SYNTHESIZED USING 2-BROMOISOBUTYRYL BROMIDE. surface initiated ATRP IS THEN CARRIED OUT WITH DMAEMA MONOMERS RESULTING IN GRAFTED-HA PARTICLES. FTIR AND TGA TESTS ARE DONE TO INVESTIGATE THE GRAFTING OF POLYMERIC CHAINS ON THE HA surface AND TO DETERMINE THE GRAFTING DENSITY OF THE CHAINS. RESULTS SHOW A SUCCESSFUL SYNTHESIS OF GRAFTED-HA PARTICLES THAT CAN BE USED IN BIOMEDICAL APPLICATIONS DUE TO THEIR ENHANCED MECHANICAL PROPERTIES.

آمار یکساله:  

بازدید 1155

دانلود 0
گارگاه ها آموزشی
نویسندگان: 

SHANMUGHARAJ A.M. | RYU SUNG HUN

اطلاعات دوره: 
  • سال: 

    2013
  • دوره: 

    22
  • شماره: 

    4
  • صفحات: 

    227-236
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    13800
  • دانلود: 

    9195
چکیده: 

In the present investigation, silica nanoparticles have been coated with poly (styrene-co-acrylonitrile) (SAN) copolymer brushes synthesized via surface-initiated atom transfer radical polymerization (ATRP). In the initial step, silica nanoparticles were functionalized with triethoxysilane-based ATR initiator, 6-(2-bromo-2-methyl) propionyloxy hexyl triethoxysilane. Successful formation of the covalent linkages between ATRP initiator and silica nanoparticles is further corroborated using thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The surface initiated ATRP of the styrene and the acrylonitrile mediated by a copper complex was carried out using the initiator fixed silica nanoparticles in the presence of a sacrificial (free) initiator. The polymerization is preceded in a living manner in all examined cases, producing nanoparticles coated with well-defined poly (styrene-co-acrylonitrile) (SAN) brushes with molecular weight in the range of 12-22 kDa. SAN-grafted silica nanoparticles were characterized using TGA which showed significant weight loss in the temperature range of 340-420oC confirming the formation of the polymer brushes on the surface with graft densities in the range of 0.109-0.190 chains/nm2. Successful formation of the SAN copolymer brushes are further characterized by FTIR and proton nuclear magnetic resonance spectroscopy techniques. Differential scanning calorimetric studies revealed that the SAN copolymer grafted onto silica nanoparticles exhibits higher glass transition temperatures than free SAN copolymers. Transmission electron microscopy and dynamic light scattering studies revealed that the SAN copolymer-grafted silica nanoparticles showed relatively fine dispersion in organic solvents such as tetrahydrofuran, when compared to bare silica nanoparticles.

آمار یکساله:  

بازدید 13800

دانلود 9195 استناد 0 مرجع 0
نویسنده: 

HEMATPOUR H. | HADDADI ASL V. | ZARGARIAN S.S.

اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    0
  • شماره: 

    11
تعامل: 
  • بازدید: 

    1470
  • دانلود: 

    0
چکیده: 

HALLOYSITE NANOTUBES (HNT) GRAFTED POLY 2-HYDROXYETHYL METHACRYLATE (PHEMA) WERE PREPARED BY surface initiated ATOM TRANSFER RADICAL polymerization (SI-ATRP). FIRSTLY HNTS WAS FUNCTIONALIZED WITH 3-AMINOPROPYLTRIETHOXY SILANE (APTES) FROM HYDROXYL GROUPS BY A COUPLING REACTION. THEN ALPHA BROMOISOBUTYRYL BROMIDE (BIBB) WAS INTRODUCED TO APTES MOIETIES IN ORDER TO OBTAIN INITIATOR ANCHORED HALLOYSITE (HNT-BR). THEAMOUNT OF MODIFICATION AND EFFECT OF DMAP ON THE YIELD OF ACYLATION REACTION WERE EVALUATED BY THERMOGRAVIMETRIC ANALYSIS (TGA). SUBSEQUENTLY, HNT-BR WAS USED FOR ATOM TRANSFER RADICAL polymerization OF 2-HYDROXYETHYL METHACRYLATE. SUCCESSFUL ATTACHMENT OF APTES, BIBB, AND PHEMA TO HNTS WERE EVALUATED BY FOURIER TRANSFORM INFRARED SPECTROSCOPY AND TGA.

آمار یکساله:  

بازدید 1470

دانلود 0
نویسندگان: 

LIU Y. | LUO L. | CHEN G. | XIE M. | YU Z.

اطلاعات دوره: 
  • سال: 

    2010
  • دوره: 

    19
  • شماره: 

    3 (117)
  • صفحات: 

    207-218
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    24517
  • دانلود: 

    34251
چکیده: 

The surface modification of ground tyre rubber (GTR) containing hydroxyl groups was carried out by atom transfer radical polymerization using a two-step reaction procedure. The process consisted of immobilization of an ATRP initiator such as 2-bromoisobutyryl bromide and controllable radical polymerization of maleic anhydride (MAH). The resulting GTR-g-MAH was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that the graft yield of new polymer could reach 69.4% on GTR surface. Then the grafted GTR was used as an adsorbent for removal of lead ions from aqueous solution. It was observed that factors such as solution pH, contact time, initial lead concentration and graft yield exerted considerable influence on lead adsorption capacity of GTR-g-MAH. The adsorption process indicated that the pseudo-second-order kinetic model fitted the experimental data well, and the equilibrium of adsorption could be described by Freundlich isotherm model. The maximum adsorption capacity of GTR-g-MAH calculated from Langmuir isotherm reached 144 mg.g-1. It was found that the GTR-g-MAH particles had significantly greater adsorption capacity and faster adsorption kinetics for lead adsorption than unmodified GTR particles.

آمار یکساله:  

بازدید 24517

دانلود 34251 استناد 0 مرجع 0
strs
اطلاعات دوره: 
  • سال: 

    2013
  • دوره: 

    0
  • شماره: 

    20
تعامل: 
  • بازدید: 

    1890
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

EXPLOITATION OF THE FASCINATING PROPERTIES OF INORGANIC NANOPARTICLES, SUCH AS OPTICAL, MAGNETIC AND ELECTRONIC PROPERTIES REQUIRES THE PARTICLES TO BE DISPERSED HOMOGENEOUSLY. THE BEST WAY TO AVOID AGGREGATION IS TO GRAFT POLYMER CHAINS ONTO THE PARTICLES COVALENTLY, FORMING ORGANICEINORGANIC HYBRID...

آمار یکساله:  

بازدید 1890

دانلود 0
اطلاعات دوره: 
  • سال: 

    2011
  • دوره: 

    20
  • شماره: 

    3 (129)
  • صفحات: 

    205-211
تعامل: 
  • استنادات: 

    315
  • بازدید: 

    30701
  • دانلود: 

    37712
چکیده: 

Arobust Monte Carlo simulation as a stochastic random-based method was employed to study the bulk photopolymerization of furfuryl methacrylate (FM) at various temperatures. An appropriate mechanism of polymerization considering a vast variety of reactions was selected and therefore, a reliable algorithm was designed. In addition, experimental results were used to evaluate the simulation procedure and algorithm and consequently, confirm the simulation results. The concentration profiles of different species with respect to irradiation time were obtained by this simulation method. In addition, the effect of temperature variation on the concentration of species has been evaluated. At higher temperatures, an increase in the rate of FM consumption was revealed which is because of an increment in the propagation rate constants of acrylic macroradicals. At 40°C of the early stages of the photopolymerization, M1* concentration increases rapidly with respect to irradiation time; this is on account of the superior primary initiation constants compared to other temperatures. However, due to the acrylic macroradicals termination, intermolecular degradative transfer, allylic-acrylic termination and acrylic primary termination, M1* concentration reaches a plateau. Moreover, the highest concentration of M1* was achieved at 0°C. A data analysis based on the least square method was performed to evaluate the FM concentration and consequently, a reliable agreement between the experimental data and the Monte Carlo simulation results were obtained at different temperatures.

آمار یکساله:  

بازدید 30701

دانلود 37712 استناد 315 مرجع 0
اطلاعات دوره: 
  • سال: 

    2020
  • دوره: 

    39
  • شماره: 

    5
  • صفحات: 

    79-94
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    11821
  • دانلود: 

    47404
چکیده: 

In this study, the modeling of polymerization of 1, 3-butadiene in the presence of hydrogen peroxide has been reported for the first time. For this purpose, the Method of double moments was applied. The modeling has been performed to investigate the effect of reaction condition on the properties of synthesized Polybutadiene, and the role of kinetic coefficients on the output of model i. e. sensitivity analysis. A comprehensive kinetic model was developed based on previous experimental studies. Then, the moment and population balance of the reactants were obtained. Modeling results were used to study the role of initiator concentration and the type of solvent in polymerization kinetics and final polymer properties. In addition, the sensitivity of modeling results in a transfer to the initiator, radical coupling and finally transfer to polymer reactions was investigated. This study opens a way for the engineering of manufacturing the Hydroxyl-Terminated PolyButadiene (HTPB) process to obtain the desired products with optimized reaction conditions. Results show that initiator concentration and type of solvent are important in polymerization kinetics and properties of HTPBs. A higher amount of initiator increases radical concentration and consequently rates of bimolecular termination and at the lower level, rate of propagation, and polymer double bonds reactions.

آمار یکساله:  

بازدید 11821

دانلود 47404 استناد 0 مرجع 0
نویسندگان: 

SEIDEL J.M. | MALMONGE S.N.M.

نشریه: 

MATERIALS RESEARCH

اطلاعات دوره: 
  • سال: 

    2000
  • دوره: 

    3
  • شماره: 

    -
  • صفحات: 

    79-83
تعامل: 
  • استنادات: 

    315
  • بازدید: 

    2723
  • دانلود: 

    9195
کلیدواژه: 
چکیده: 

آمار یکساله:  

بازدید 2723

دانلود 9195 استناد 315 مرجع 0
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