共查询到20条相似文献，搜索用时 0 毫秒
1.
Alaitz Ruiz de Luzuriaga Agustín Etxeberria Javier Rodríguez José A. Pomposo 《先进技术聚合物》2008,19(7):756-761
An entropic model is introduced for the prediction of the χ interaction parameter and phase diagram of athermal all‐polymer nanocomposites (chemically identical polymer‐nanoparticle/linear‐polymer blends). According to this model, dilution of contact (hard sphere‐like) nanoparticle/nanoparticle interactions upon mixing plays a key role in explaining the miscibility behavior of athermal all‐polymer nanocomposites in the presence of unfavorable chain expansion (or contraction) effects. The new model is valid both for the cases of chain stretching and chain contraction and provides an appropriate capture of entropy changes accompanying the mixing of chemically identical nanoparticles and polymers. A good agreement was found between predicted χ interaction parameter (χcal = ?2.3 × 10?3) and reported small angle neutron scattering (SANS) experimental data ( ～ ?2 × 10?3) for 211 kDa cross‐linked poly(styrene) (PS)‐nanoparticles dissolved in 473 kDa deuterated linear‐PS. In addition, the miscibility boundary calculated from the model for PS‐nanoparticle/linear‐PS nanocomposites (?1 = 0.02) compared very favorably to that experimentally found. For this system, the spinodal line in the polymer radius of gyration (Rg) versus nanoparticle radius (a) phase diagram was found to follow the simple scaling law: , being the polymer radius of gyration at which the second derivative of the free energy of mixing vanishes. Finally, the model has been employed for the prediction of the entropic χ interaction parameter, the miscibility behavior, and the melting point depression of athermal poly(ethylene) (PE)‐nanoparticle/linear‐PE nanocomposites using recent chain dimension data from Monte Carlo (MC) simulations, where chain stretching or chain contraction effects were observed depending on nanoparticle size. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
2.
Mukesh Agrawal Nikolaos E. Zafeiropoulos Smrati Gupta Ekaterina Svetushkina Jürgen Pionteck Andrij Pich Manfred Stamm 《Macromolecular rapid communications》2010,31(4):405-410
A novel and versatile approach for the mixing of ZnO nanofillers into a host polymer matrix, poly(ethyl methacrylate) (PEMA), is reported. Firstly, ZnO nanoparticles are deposited onto the surface of polystyrene (PS) colloidal particles in a “raspberry‐like” fashion and subsequently obtained PS/ZnO composite particles are mixed into the PEMA matrix in the range of 0.5 to 5 wt.‐%. Microscopic analyses reveal a homogenous distribution of PS/ZnO domains into the PEMA matrix even at 5 wt.‐% loading level. Thermogravimetric analysis and differential scanning calorimetry results indicate an improvement in thermal stability of PEMA matrix after mixing with PS/ZnO filler particles. A significant enhancement in mechanical properties of PEMA matrix in the presence of PS/ZnO particles has been evidenced by dynamic mechanical analysis and three point bending measurements.
3.
C. Zamecnik M. J. Loureiro C. Postnikoff Y. Kong A. Penlidis 《高分子科学杂志，A辑:纯化学与应用化学》2013,50(10):906-909
In this study, poly(N-isopropylacrylamide) (PNIPAAM) hydrogels were synthesized via a liquid template polymerization method using 200–400 nm polydimethylsiloxane (PDMS) droplets as the porogens, which were stabilized by sodium dodecyl sulfate (SDS). Similar hydrogels were also synthesized with iron (III) oxide superparamagnetic nanoparticles embedded within the gel. These gels were subjected to freeze- or air-drying, and then imaged using scanning electron microscopy. It was found that pores were not accessible from the surface of the freeze-dried gels, but were visible on the surface parallel to the crack plane within the polymer. In contrast, air-dried gels exhibited a well-defined nanoporous structure on the surface. The iron oxide nanoparticles did not have a significant effect on the hydrogel morphology. 相似文献
4.
James D. Mayo Sonia Behal Alex Adronov 《Journal of polymer science. Part A, Polymer chemistry》2009,47(2):450-458
Phase separation of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blends was used as a means to segregate PS‐ or PMMA‐functionalized single‐walled carbon nanotubes (SWNTs) in thin films. Dilute solutions (5 wt % in THF) of 1:1 PS/PMMA blends containing the functionalized nanotubes were spin cast and annealed at 180 °C for 12 h. Two different polymer molecular weights were used (Mn = 8000 or Mn = 22,000), and were of approximately equivalent molecular weight to those attached to the surface of the nanotubes. Nanotube functionalization was accomplished using the Cu(I)‐catalyzed [3 + 2] Huisgen cycloaddition, in which alkyne‐decorated nanotubes were coupled with azide‐terminated polymers, resulting in polymer‐SWNT conjugates that were soluble in THF. Characterization of the annealed films by scanning Raman spectroscopy, which utilized the unique Raman fingerprint of carbon nanotubes, enabled accurate mapping of the functionalized SWNTs within the films relative to the two phase‐separated polymers. It was found that nanotube localization within the phase‐separated polymer films was influenced by the type of polymer attached to the nanotube surface, as well as its molecular weight. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 450–458, 2009 相似文献
5.
6.
Luca Valentini Silvia Bittolo Bon Josè Kenny 《Journal of Polymer Science.Polymer Physics》2013,51(13):1028-1032
A simple and solvent‐free practical way to obtain freestanding poly(methyl methacrylate)/graphene oxide films is reported. Falling liquid droplets are used to produce an impulse necessary for the mechanical excitation of such composite films. A pressure wave is generated on the surface of the films by the impact. It is reported how such films are able to convert mechanical energy of the impact to electrical power. The reported example is of interest to enhance the mechanical energy harvesting and to add new functionalities to traditional polymer nanocomposites. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1028–1032 相似文献
7.
A review of recent trends in the dispersion, purification, and assembly of colloidal nanoparticles highlights a number of growing analogies with ideas borrowed from polymer science. Beyond the similar scales of size, several key concepts lying at the foundation of polymer physics—such as polydispersity, fractionation, phase ordering, and viscoelasticity—are taking on new and unique significance in the contemporary realm of nanotechnology. Leveraging “soft matter” at the nanoscale to simplify materials processing and improve material performance is becoming a reality, with potentially profound implications for a number of emerging technologies. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym. Phys. 2013 , 51, 1195–1208 相似文献
8.
9.
Achmad Syafiuddin 《中国化学会会志》2019,66(8):793-814
This article provides a comprehensive understanding of development of textiles functionalized with silver nanoparticles (AgNPs). There are three established methods to fabricate textiles functionalized with AgNPs, namely, solution‐immersion, layer‐by‐layer deposition, and sonochemical. In addition, several textile types such as cotton, wool, polyester, silk, cotton/polyester blend, polyamide, and regenerated cellulose have been used for the fabrication. The AgNP deposition mechanism on textiles is mainly due to electrostatic interaction between AgNPs and textile constituents. It was exhibited that the deposition of AgNPs on textiles can transform their textiles colors. In addition, it was demonstrated that the deposition of AgNPs on textiles is not permanent, particularly against washing treatment. Textiles modified with AgNPs have several promising applications such as antibacterial, antifungal, catalyst, electronic devices, water treatment, sun protection, air treatment, and surface‐enhanced Raman scattering, which are comprehensively discussed in this article. Future challenges in fabricating textiles functionalized with AgNPs remain on how this can be carried out to improve long‐term stabilization of AgNPs on textiles to achieve their permanent deposition by employing greener approaches. 相似文献
10.
Yang‐Fei Zhang Shu‐Lin Bai Xiong‐Kui Li Zhong Zhang 《Journal of Polymer Science.Polymer Physics》2009,47(10):1030-1038
The viscoelastic properties of the epoxy filled with silica nanoparicles have been investigated by dynamic nanoindentation and characterized by the storage modulus and loss tangent. The materials studied are neat epoxy and silica/epoxy composites with silica volume fraction of 1, 3, 6, 10, and 14 vol %, respectively. The silica nanoparticles with an average diameter of 25 nm are found to disperse homogeneously in the epoxy matrix. The effect of the particle content, force frequency, and penetration load on the viscoelastic behavior is studied and discussed. The comparison with traditional testing methods such as tension, bending, and DMTA is made. Besides, theoretical results by using micromechanics models are also obtained and compared with the experimental results. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1030–1038, 2009 相似文献
11.
The sol–gel method of synthesis of the hybrid nanocomposite films of ZnO/(2‐hydroxypropyl) cellulose (HPC) on silica glass is presented. The sol phases were prepared for different weight ratios of zinc acetate dihydrate to HPC in the presence of triethylamine (TEA). Raman spectrum of the mixture of ZnAc and HPC indicates coordinating interaction between zinc ion and HPC. The generation of ZnO nanoparticles in the HPC matrix proceeds in situ through the annealing of the gel phase at a temperature of 160°C. Identification of ZnO nanoparticles in the HPC matrix is done by using photoluminescence (PL), UV–Vis, and Raman spectroscopy. The films of ZnO/HPC nanocomposite are transparent in the visible light and show a higher energy value of absorption edge compared with ZnO in the bulk. Nanocrystalline films of ZnO were obtained by the calcination of ZnO/HPC nanocomposite at 500°C. ZnO films possess a good transparency for the visible light and high absorbance for UV light. Nanocrystallite sizes of ZnO particles were estimated from the X‐ ray lines broadening. The properties of ZnO layers were studied by the evaluation of PL, X‐ray investigation and atom force microscope (AFM) scanning, and the optical absorption edge. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
12.
13.
Chung WJ Simmonds AG Griebel JJ Kim ET Suh HS Shim IB Glass RS Loy DA Theato P Sung YE Char K Pyun J 《Angewandte Chemie (International ed. in English)》2011,50(48):11409-11412
14.
Gang He Valeriy V. Ginzburg Anna C. Balazs 《Journal of Polymer Science.Polymer Physics》2006,44(17):2389-2403
Nanoparticle additives provide a means of imparting the desired electrical, optical, or mechanical properties to a polymeric matrix. The difficulty faced in creating these composites is determining the optimal conditions for forming a thermodynamically stable mixture, where the particles will not phase separate from the matrix material. This challenge is even more daunting when the polymeric matrix is itself a multicomponent mixture, as is often the case in advanced materials. Ideally, the nanoparticles would not only contribute the needed physical properties, but also stabilize the mixture so that the entire system forms a single‐phase system. In this study, we use a free energy expression for a binary blend that contains nanoparticles and take the interaction parameters between the different species to be independent variables. Thus, the particles can have distinct enthalpic interactions with each of the polymeric components. Using this expression, we determine the conditions under which the mixture forms a stable, single‐phase material. In particular, we isolate how variations in the system's parameters (e.g., polymer composition, particle volume fraction, particle size, interaction energies) affect the phase diagrams. The findings provide guidelines for creating effective formulations and can allow researchers to understand how choices made in the nature of the components affect the overall macroscopic properties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2389–2403, 2006 相似文献
15.
16.
Brett W. Guralnick Jonathan E. Seppala Michael E. Mackay 《Journal of Polymer Science.Polymer Physics》2011,49(11):772-780
Previously we characterized the active layer in polymer‐based solar cells containing Poly(3‐hexylthiophene) with the electron acceptor Phenyl‐C61‐butyric acid methyl ester (PCBM) to find a thin, pure polymer layer at the air interface just after spin coating. In this study, we find that when the aluminum back electrode was thermally evaporated onto the active layer, at high enough rate, craters were found in the pure polymer layer. This was determined by dissolving the aluminum and characterizing the active layer with an atomic force microscope. Poor device performance was noted under this condition. However, if the aluminum was evaporated at a slower rate, resulting in a flat active layer surface and no crater formation, the efficiency more than doubled. A similar result is found if lithium fluoride (LiF) is deposited before aluminum evaporation and no craters were found even for the higher aluminum evaporation rate. So, it appears that LiF acts as a momentum shield to crater formation allowing superior device performance. If the active layer is annealed before deposition of the back electrode then, regardless of deposition rate, similar device performance is found. Again, in our previous study, it was found that annealing the active layer forced PCBM to the air interface which apparently also acts as a momentum shield. Annealing the device after aluminum deposition produces poorer performance than annealing before deposition. However, these devices have a better fill factor. Examining the active layer shows that it undergoes a buckling transition due to differences in the aluminum and active layers' thermal expansivities which reduces overall contact with the electrodes. However, whatever contact is made, is superior, accounting for the improved fill factor. If the buckling instability could be avoided then this processing procedure may be used in the future to manufacture even better devices than with any of the other annealing procedures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
17.
Zhao Z Jacovetty EL Liu Y Yan H 《Angewandte Chemie (International ed. in English)》2011,50(9):2041-2044
18.
19.
Toshimi Shimizu 《Journal of polymer science. Part A, Polymer chemistry》2006,44(17):5137-5152
Supramolecular nanotube hosts with precisely controlled inner or outer diameters have been synthesized by self-assembly of unsymmetrical bolaamphiphilic monomers or glucopyranosylamide lipids, respectively. Time-resolved fluorescent measurement using 8-anilinonaphthalene-1-sulfonate (ANS) as a probe revealed that the water confined in a cardanyl-β-D -glucopyranoside lipid nanotube has relatively lower solvent polarity corresponding to that of propanol than bulk water. Extensively developed hydrogen bond networks also characterize the confined water in comparison to the case in bulk water. Encapsulation ability of the glucopyranosylamide lipid nanotube has been examined by filling the lyophilized LNTs with gold or silver nanoparticles, ferritin, or magnetic crystals. Filling the unsymmetrical bolaamphiphile nanotube possessing positively charged inner surfaces with negatively charged polymer beads or ferritin proved to be successful without depending on capillary action. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5137–5152, 2006 相似文献
20.
Yves Termonia 《Journal of Polymer Science.Polymer Physics》2015,53(12):869-875
We present a Monte Carlo simulation study of the Brownian motion of polymer chains in a melt confined in a periodically asymmetric channel of nanometric dimensions. We assume no friction between the chains and the channel. A detailed analysis of the conformations of the chains reveals the presence of a favorable entropy gradient along the easy flow direction. For high molecular weight chains, this gradient is seen to drive a self‐sustained polymer flow with Peclet numbers as high as 0.9, which makes our observation experimentally accessible. Much weaker efficiences are observed at low molecular weights. We show that the unexpected directed Brownian motion of polymers in confined geometries is of significant importance in the design and stabilization of platelet nanocomposites which typically age over time under quiescent conditions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 869–875 相似文献