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متن کامل


اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    22
تعامل: 
  • بازدید: 

    144
  • دانلود: 

    0
چکیده: 

LIVING CONTROLLED RADICAL polymerization HAS BEEN A POWERFUL TECHNIQUE TOSYNTHESIZE WELL-DEFINED STRUCTURE POLYMER BY CONTROLLING MOLECULAR WEIGHT, MOLECULAR WEIGHT DISTRIBUTION AND TAILORED ARCHITECTURE. THREE ‘‘LIVING’’ RADICALpolymerization TECHNIQUES WHICH ARE RECEIVING MORE AND MORE ATTENTION INACADEMIA ARE NITROXIDE-MEDIATED RADICAL polymerization (NMP) [1], ATOM TRANSFERRADICAL polymerization (ATRP) [2], AND REVERSIBLE ADDITION–FRAGMENTATION CHAINTRANSFER (RAFT) polymerization [3]. RAFT polymerization WAS CONSIDERED AS ONE OFTHE MOST PROMISING CONTROLLED FREE RADICAL polymerization DUE TO ITS COMPATIBILITYWITH A WIDE RANGE OF MONOMERS AND ITS VERSATILITY.IN THE PRESENT WORK, A NOVEL NANOCOMPOSITE WAS PREPARED BASED ON POLY (METHYL METHACRYLATE) /SIO2 USING 4-CYANO-4- [(PHENYLCARBOTHIOYL) SULFANYL] PENTANOIC ACID AS A RAFT AGENT (FIGURE 1).THE STRUCTURE, MORPHOLOGY AND THERMAL PROPERTIES OF THE NANOCOMPOSITES WERE CHARACTERIZED USING FOURIER TRANSFORM INFRARED (FT-IR), HNMR, TRANSMISSION ELECTRON MICROSCOPY (TEM), THERMOGRAVIMETRIC ANALYSIS (TGA), AND DIFFERENTIAL SCANNING CALORIMETRY (DSC), RESPECTIVELY. THE XRD RESULTS ALSO SHOWED THE PROPER INTERCALATION OF POLYMER CHAINS BETWEEN THE SILICATE LAYERS.

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بازدید 144

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اطلاعات دوره: 
  • سال: 

    2013
  • دوره: 

    20
تعامل: 
  • بازدید: 

    121
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

POLYMER–INORGANIC HYBRIDS, BASED ON THE INTERCALATION OF POLYMER CHAINS INTO LAYERED SILICATES, FORM A CLASS OF NANOCOMPOSITES THAT HAVE RECENTLY RECEIVED CONSIDERABLE ATTENTION FROM BOTH ACADEMIA AND INDUSTRY AS AN EFFECTIVE MEANS OF OVERCOMING THE SHORTCOMINGS OF CONVENTIONAL MINERAL-FILLED...

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بازدید 121

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اطلاعات دوره: 
  • سال: 

    2012
  • دوره: 

    31
  • شماره: 

    3 (63)
  • صفحات: 

    75-84
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    445
  • دانلود: 

    0
چکیده: 

In this work, based on experimental observations and exact theoretical predictions, the kinetic scheme of RAFT polymerization is extended to a wider range of reactions such as irreversible intermediate radical terminations and reversible transfer reactions. The reactions which have been labeled as kinetic scheme are the more probable existing reactions as the theoretical point of view. The detailed kinetic scheme is applied to three kinds of RAFT polymerization system by utilizing the Monte Carlo simulation Method. To do this, a new approach of simulation method was used. In this approach, a multi-reaction step was used in each time step. Unknown kinetic rate constants have obtained by curve fitting of the simulation results and theoretical data, applying the least square method; or estimated by considering theoretical facts and experimental findings. The origin of the rate retardation and induction period has been understood by studying the main and pre-equilibrium stages of dithiobenzoate-mediated RAFT homo polymerization. A copolymerization system in the presence of RAFT agent has also been examined to confirm the capability of introduced simulation method in different monomer/RAFT agent systems. The simulation results were in excellent agreement with experimental data, which proves the validity and applicability of the Monte Carlo algorithm.

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بازدید 445

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نشریه: 

Iranian Polymer Journal

اطلاعات دوره: 
  • سال: 

    2011
  • دوره: 

    20
  • شماره: 

    6 (132)
  • صفحات: 

    459-478
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    444
  • دانلود: 

    0
چکیده: 

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 dithiobenzoates) still have remained unsolved. In this work, based on experimental observations and exact theoretical predictions, the kinetic schemes of RAFT polymerization are extended to a wider range of reactions such as irreversible intermediate radical terminations and reversible transfer reactions.The reactions which have been labeled as kinetic schemes are theoretically the most probable existing reactions and are used for mathematical modelling. The detailed kinetic scheme is applied to three kinds of RAFT polymerization systems by utilizing the method of moments. Unknown kinetic rate constants are obtained by curve fitting of the modelling results and theoretical data, and applying the least square method; or estimation by considering the theoretical facts and experimental findings. The origin of the rate retardation and induction periods has been understood by studying the main and pre-equilibrium stages of dithiobenzoate-mediated RAFT homopolymerization. A copolymerization system in the presence of RAFT agent has also been examined to confirm the capability of introduced kinetic scheme in different monomer/RAFT agent systems. Although unknown parameters were obtained theoretically, their consistency with other researchers' works shows the accuracy of the modelling procedure. The modelling results are in excellent agreement with experimental data which proves the validity and applicability of the detailed kinetic scheme. The results have shown that some reactions may not occur in many RAFT polymerization systems and can be eliminated and therefore more kinetic and mechanistic studies are required.

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بازدید 444

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اطلاعات دوره: 
  • سال: 

    2015
  • دوره: 

    23
تعامل: 
  • بازدید: 

    170
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

CELLULOSE ARE BIODEGRADABLE AND IS PREDICTED AS AN ALTERNATIVE TO SYNTHETIC MATERIALS IN THISPROJECT.THE MAIN DISADVANTAGEOUS OF CELLULOSE IS ITS LOW SOLUBILITY. THE polymerization OF THECELLULOSE CHANGED ITS SURFACE PROPERTIES AND ALSO INCREASED ITS SOLUBILITY IN POLARSOLVENTS.1 REVERSIBLE ADDITION – FRAGMENTATION CHAIN TRANSFER polymerization (RAFT) WAS USEDTO GRAFTNOVEL POLYMERIC COMPONENT TOTHE CELLULOSE….

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بازدید 170

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اطلاعات دوره: 
  • سال: 

    2016
  • دوره: 

    24
تعامل: 
  • بازدید: 

    153
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

NOWADAYS, ONE OF THE CONCERNS OF HUMAN SOCIETY IS THE CANCER TOPIC, ACCORDING TONUMEROUS CANCER-CAUSING FACTORS IN THE DEVELOPED WORLD. IN ORDER TO OVERCOME THESE PROBLEMSTODAY, DRUGS TARGETING STRATEGY IS USED. TARGETED DRUG DELIVERY IS OFTEN DIVIDED INTO TWOCATEGORIES, PASSIVE AND ACTIVE. IN ACTIVE TARGETING, THERAPEUTIC AGENT ALONG WITH A CARRIER, ATTACHED TO A SPECIFIC CELL OR TISSUE. ACTIVE TARGETING BENEFITS INCLUDE OF ABILITY TO MAINTAINDRUG CONCENTRATION IN RELATIVELY CONSTANT FOR A SPECIFIED PERIOD OF TIME, THE POSSIBILITY OFDELIVERING MEDICINE TO A PARTICULAR ORGAN OR TISSUE, TAKE DELIVERY IN NANOMETER DIMENSIONSANDETC [1, 2]…..

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بازدید 153

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نویسندگان: 

SALAMI KALAJAHI M. | HADDADI ASL V.

اطلاعات دوره: 
  • سال: 

    2012
  • دوره: 

    19
  • شماره: 

    2
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    170
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

شاخص‌های تعامل:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

بازدید 170

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نویسندگان: 

SALAMI KALAJAHI M. | HADDADI ASL V.

اطلاعات دوره: 
  • سال: 

    2012
  • دوره: 

    32
  • شماره: 

    1
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    149
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 149

مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesدانلود 0 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesاستناد 1 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resourcesمرجع 0
اطلاعات دوره: 
  • سال: 

    2013
  • دوره: 

    20
تعامل: 
  • بازدید: 

    140
  • 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...

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بازدید 140

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نویسندگان: 

HAWTHORNE D.G. | MOAD G. | RIZZARDO E. | THANG S.H.

نشریه: 

MACROMOLECULES

اطلاعات دوره: 
  • سال: 

    1999
  • دوره: 

    32
  • شماره: 

    16
  • صفحات: 

    5457-5459
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    87
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 87

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