共查询到20条相似文献,搜索用时 15 毫秒
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Yong Chae Jung Hiroyuki Muramatsu Ki Chul Park Daisuke Shimamoto Jin Hee Kim Takuya Hayashi Sung Moo Song Yoong Ahm Kim Morinobu Endo Mildred S. Dresselhaus 《Macromolecular rapid communications》2009,30(24):2084-2088
It is demonstrated that an optically transparent and electrically conductive polyethylene oxide (PEO) film is fabricated by the introduction of individualized single‐walled carbon nanotubes (SWNTs). The incorporated SWNTs in the PEO film sustain their intrinsic electronic and optical properties and, in addition, the intrinsic properties of the polymer matrix are retained. The individualized SWNTs with smaller diameter provide high transmittance as well as good electrical conductivity in PEO films.
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Marija R. Gizdavic‐Nikolaidis Dragomir R. Stanisavljev Allan J. Easteal Zoran D. Zujovic 《Macromolecular rapid communications》2010,31(7):657-661
We present the first fast and facile microwave assisted synthesis of polyaniline (PANI) nanofibers (“MWA synthesis”). Under conventional synthesis (CS), the polymer was produced with 79.7% yield after 5 h at ambient temperature. However, under microwave irradiation, the nanofibers were produced with yield of 76.2% after only 5 min, i.e., with 78.8% after 20 min at ambient temperature. The FTIR and Raman spectra show the PANI structure in all samples either synthesized conventionally or in the microwave. SEM and TEM confirm the nanofibrillar morphology.
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Sergey Vyazovkin Ion Dranca Xiaowu Fan Rigoberto Advincula 《Macromolecular rapid communications》2004,25(3):498-503
Summary: Thermogravimetry and differential scanning calorimetry have been used to study the thermal and thermo‐oxidative degradation of polystyrene (PS) and a PS–clay nanocomposite. An advanced isoconversional method has been applied for kinetic analysis. Introduction of the clay phase increases the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials.
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Summary: This study aims at developing a highly electronic conductive microporous structure from thermoplastic polymers filled with carbon black (CB) and graphite (GR). The matrix was a low viscosity poly(propylene) (PP) and the conductive additives were composed of high specific surface area CB and synthetic flake GR. Conductive blends were first developed using a corotating twin‐screw extruder. Rheological properties and conductivities of these blends were then characterized as a function of blend composition. Blends that show the best compromise between electronic conductivity and processability were subsequently extruded through a sheet die to obtain films of around 500 µm in thickness. These films were then stretched in two successive steps under controlled temperature and stretching rate to generate a film of controlled microporous structure.
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Equilibrium and non‐equilibrium molecular dynamics simulations of flexible polymer chains absorbed on heterogeneous surfaces are presented. The surfaces are flat but energetically disordered, consisting of a random mixture of weakly and more strongly absorbing sites (94 and 6%, respectively). For comparison, the two corresponding homogeneous surfaces are also simulated. This apparently weak energetic disorder can produce significant changes of the chain statistics, equilibrium dynamics, and non‐equilibrium response to a horizontal pulling force. On the disordered surfaces, the polymer–surface effective friction coefficient becomes strongly force‐dependent, as the dominant mode of motion changes from localized stick–slip events to smooth and continuous sliding. This is strongly reminiscent of the Schallamach model of rubber friction and the Maier–Göritz picture of the Payne effect in filled elastomers.
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Youhei Fujimoto Suprakas Sinha Ray Masami Okamoto Akinobu Ogami Kazunobu Yamada Kazue Ueda 《Macromolecular rapid communications》2003,24(7):457-461
Via a batch process in an autoclave, the foam processing of neat polylactide (PLA) and two different types of PLA/layered silicate nanocomposites has been conducted using supercritical carbon dioxide as a foaming agent. The morphological correlation between the dispersed silicate particles with nanometer dimensions in the bulk and the obtained closed‐cell structure of the foam is discussed. This is the first report that deals with the possibility of preparing biodegradable nanocellular polymeric foams via nanocomposite technology.
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Andreas Bartsch Wibke Dempwolf Marc Bothe Silke Flakus Gudrun Schmidt‐Naake 《Macromolecular rapid communications》2003,24(10):614-619
Chlorine‐functionalized TEMPO‐capped polystyrenes were investigated using the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) technique. Amine‐ and acrylate‐functionalized agents and bifunctional TEMPO‐capped polystyrene were also analyzed to demonstrate the applicability of this method. Using this technique allowed to analyze the conversion of the chlorine function to an acrylate function, which was previously difficult to detect with other methods.
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Kai Zhang Bernd Tieke Filipe Vilela Peter J. Skabara 《Macromolecular rapid communications》2011,32(11):825-830
π‐Conjugated microporous networks have been prepared from the tetraarylated diketopyrrolo[3,4‐c]pyrrole unit as a tetrafunctional building block. The reactions are carried out using microwave‐assisted Yamamoto or Sonogashira cross‐coupling. Red insoluble powders are obtained, showing intense fluorescence. The polymer networks exhibit a high gas storage capability, with BET surface areas up to about 500 m2 · g−1.
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Jason E. Bara Richard D. Noble Brian J. Elliott 《Macromolecular rapid communications》2008,29(5):367-389
Cross‐linked lyotropic liquid crystal (LLC) assemblies represent a new class of polymer materials for membrane applications. These materials are formed by the phase‐segregation and self‐assembly of polymerizable amphiphiles in water into condensed ordered ensembles that can be cross‐linked in situ with retention of microstructure. The resulting LLC polymer networks have ordered, nanometer‐scale aqueous and cross‐linked organic domains, which can be used to affect gas solubility and diffusivity through the polymer to help separate molecules via the solution–diffusion mechanism. The open aqueous domains can also be used for pore transport and size exclusion with resolution on the molecular size level. The use and application potential of cross‐linked LLC assemblies as gas separation membranes, selective vapor barrier materials, and water nanofiltration and desalination membranes are presented.
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Zhilu Liu Neelam Khan Haiyuan Hu Bo Yu Jianxi Liu Miao Chen Feng Zhou 《Macromolecular rapid communications》2008,29(24):1937-1943
Binary reactive/inert antifouling polymer brushes were grafted via a two step surface initiated polymerization from printed initiator monolayer and provided robust, effective polymeric surfaces for bioattachment with distinguishably reduced non‐specific adsorption. This synthetic strategy can be harnessed to build complex binary polymeric structures on substrate surfaces and the polymer brush surfaces reported in the present paper can be widely used for versatile biological study.
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Kristian Kempe Antje Vollrath Hendrik W. Schaefer Tobias G. Poehlmann Christoph Biskup Richard Hoogenboom Stephanie Hornig Ulrich S. Schubert 《Macromolecular rapid communications》2010,31(21):1869-1873
New multifunctional copoly(2‐oxazoline) nanoparticles were prepared for cell studies. The polymer contains double‐bond side chains as potential reaction sites for “thio”‐click reactions as well as a fluorescein label covalently bound to the polymer backbone. Using the nanoprecipitation technique, spherical nanoparticles of 200–800 nm were obtained. Confocal laser scanning microscopy measurements revealed the cellular uptake of the nanoparticles.
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ChooJin Park Dong Choon Hyun Min‐Cheol Lim Su‐Jeong Kim Young‐Rok Kim Hyun‐Jong Paik Unyong Jeong 《Macromolecular rapid communications》2011,32(16):1247-1252
This study reports a continuous prepartion of spherical or hemispherical polymer particles simply utilizing the phase separation in polymer blend films during the coating process. We took an advantage of the strong phase separation between a water‐soluble crystalline polymer as a matrix and hydrophobic polymers as minor components. We demonstrated the prepartion of water‐soluble polystyrene (PS) particles, nitrilotriacetic acid (NTA)‐functionalized PS particles for protein separation, and semiconducting poly(3‐hexylthiophene) (P3HT) particles. The sizes of the particles could be controlled by adjusting the film thickness and weight fraction of the minor component polymers in the blend film. It provides a simple facile way to prepare polymer particles in a continous process.
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Christophe Plessis Gurutze Arzamendi Juan M. Alberdi Alex M. van Herk Jos R. Leiza Jos M. Asua 《Macromolecular rapid communications》2003,24(2):173-177
Branched poly(butyl acrylate) was obtained from pulsed‐laser polymerizations carried out in bulk and in solution between −16 and 60 °C. The predominantly short branches are formed by backbiting. The Arrhenius temperature dependence of the backbiting rate is calculated, and the activation energy of this process was found to be remarkably higher than that of propagation. Branching thus increases with temperature leading to broader SEC traces and difficulties in the accurate determination of kp.
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Nicky Chan Michael F. Cunningham Robin A. Hutchinson 《Macromolecular rapid communications》2011,32(7):604-609
The use of copper tubing as both the reactor and as a catalyst source is demonstrated for continuous controlled radical polymerization of methyl acrylate at ambient temperature and at low solvent content of 30%. The high surface area provided by the copper walls mediates the reaction via the single electron transfer–living radical polymerization (SET‐LRP) mechanism. The polymerizations proceeded quickly, reaching 67% conversion at a residence time of 16 min. Ligand concentration could also be reduced without a sharp drop in polymerization rate, demonstrating the potential for decreased raw material and post‐process purification costs. Chain extension experiments conducted using synthesized polymer showed high livingness. The combination of living polymer produced at high polymerization rates at ambient temperature and low volatile organic solvent content demonstrate the potential of a copper reactor for scale up of SET‐LRP.