共查询到20条相似文献,搜索用时 15 毫秒
1.
Kai Du Aihua H. He Xin Liu Charles C. Han 《Macromolecular rapid communications》2007,28(24):2294-2299
Highly exfoliated poly(propylene) (PP)/clay nanocomposites with obvious improvements in both the tensile strength and toughness have been prepared by a novel TiCl4/MgCl2/imidazolium‐modified montmorillonite (IOHMMT) compound catalysts. Through this approach, in situ propylene polymerization can actually take place between the silicate layers and lead not only to PP with a high isotacticity and molecular weight, but also to a highly exfoliated structure even at high clay content levels (as high as 19 wt.‐%).
2.
Shanju Zhang Lingbo Zhu Ching‐Ping Wong Satish Kumar 《Macromolecular rapid communications》2009,30(22):1936-1939
Carbon nanotube–polymer composite fibers are obtained by infiltration of a monomer liquid into aligned carbon nanotube aerogel fibers with subsequent in situ polymerization. The monomer, methyl methacrylate (MMA), was infiltrated into the aerogel fibers of multi‐walled carbon nanotubes (MWNTs) at room temperature and subsequently polymerized at 50 °C into poly(methyl methacrylate) (PMMA). Cross‐sections of the PMMA/MWNT composite fibers showed that the PMMA filled the spaces of the nanotube fibers and bound the nanotubes together. PMMA in the composite fibers exhibited local order. The resultant composite fibers with 15 wt.‐% nanotube loading exhibited a 16‐fold and a 49‐fold increase in tensile strength and Young's modulus, respectively, compared to the control PMMA.
3.
We report a facile method to accomplish the crosslinking reaction of PVA with SWNTs, MWNTs, and C‐60 using MW irradiation. Nanocomposites of PVA crosslinked with SWNT, MWNT and C‐60 were prepared expeditiously by reacting the respective carbon nanotubes with 3 wt.‐% PVA under MW irradiation, maintaining a temperature of 100 °C, representing a radical improvement over literature methods to prepare such crosslinked PVA composites. This general preparative procedure is versatile and provides a simple route to manufacture useful SWNT, MWNT and C‐60 nanocomposites.
4.
Jae Whan Cho Jeong Won Kim Yong Chae Jung Nam Seo Goo 《Macromolecular rapid communications》2005,26(5):412-416
Summary: Electro‐active shape‐memory composites were synthesized using conducting polyurethane (PU) composites and multi‐walled carbon nanotubes (MWNTs). Surface modification of the MWNTs (by acid treatment) improved the mechanical properties of the composites. The modulus and stress at 100% elongation increased with increasing surface‐modified MWNT content, while elongation at break decreased. MWNT surface modification also resulted in a decrease in the electrical conductivity of the composites, however, as the surface modified MWNT content increased the conductivity increased (an order of 10−3 S · cm−1 was obtained in samples with 5 wt.‐% modified‐MWNT content). Electro‐active shape recovery was observed for the surface‐modified MWNT composites with an energy conversion efficiency of 10.4%. Hence, PU‐MWNT composites may prove promising candidates for use as smart actuators.
5.
In this communication, the synthesis, characterization, and properties of highly conductive core–shell nanocomposites of poly(N‐vinylcarbazole) (PNVC)–polypyrrole (PPY) copolymers with multi‐walled carbon nanotubes (MWCNTs) are described. A unique free‐radical coupling reaction between PNVC and PPY cation radicals in chloroform solvent, using feric chloride as an oxidant, in the presence of suspended MWCNTs in the reaction medium, was used for the synthesis of nanocomposite. Field‐emission scanning and transmission electron microscopy studies showed the formation of the core–shell nanocomposite. Raman spectrocopy results as well as thermogravimetric analysis supported the electron microscopic observations. The resulting PNVC–PPY copolymer‐coated MWCNTs showed an unprecedentedly increased value of direct electrical conductivity (bulk) compared to the conductivity of all samples even with pure MWCNTs.
6.
Summary: Nanocomposites were formulated by curing a sonicated mixture of epoxy resin, C18 clay, and acrylic rubber dispersants. At 5.5 phr (parts per hundred) organoclay loading and a rubber concentration of 15 phr, the tensile‐failure strain of the nanocomposite was found to be higher than that of epoxy nanocomposite, rubber‐dispersed epoxy, and pristine epoxy. A plausible mechanism for improvement of the failure strain of nanocomposites is proposed.
7.
DNA fibers were prepared by solution spinning of DNA in a lysozyme (LSZ) coagulation/gelation bath. Strong positive charges carried by LSZ protein condensed the DNA (strong negative charged) molecules resulting in self‐assembly and the formation of fibrillar structures in a gel‐like network. DNA/LSZ fibril formation was found to be dependent on the ratio of DNA to LSZ. A minimum 0.1 wt.‐% of LSZ was necessary to condense 0.1 wt.‐% of DNA into micro‐fibrils. Macroscopic fiber spinning was possible by introducing a 0.1 wt.‐% DNA aqueous solution into a 0.2 wt.‐% LSZ coagulation bath which resulted in fibers with ≈20 µm diameter. Single‐walled carbon nanotubes (SWNT) were also incorporated into these fibers to explore the possibility for creating hybrid materials. All DNA‐based fibers exhibit strong birefringence confirming molecular orientation along the fiber axis. Due to the presence of LSZ, the fibers exhibit antimicrobial activity against bacteria like Micrococcus lysodeikticus.
8.
Sophie Barrau Philippe Demont Cline Maraval Alain Bernes Colette Lacabanne 《Macromolecular rapid communications》2005,26(5):390-394
Summary: The glass transition temperatures of conducting composites, obtained by blending carbon nanotubes (CNTs) or polypyrrole (PPy) particles with epoxy resin, were investigated by using both differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). For both composites, dc and ac conductivity measurements revealed an electrical percolation threshold at which the glass transition temperature and mechanical modulus of the composites pass through a minimum.
9.
One‐dimensional methyl orange fibrils can be easily prepared. They are stable in acidic aqueous solutions and soluble in neutral water. When used to synthesize conducting polymer microtubules, the fibrils act as “hard templates” formally but as “soft templates” effectively. Microtubular structures of polypyrrole, polyaniline, and poly(3,4‐ethylenedioxythiophene) have been achieved successfully via such water‐soluble versatile templates.
10.
Lanyong Zhang Huan Sun Di Li Shiping Song Chunhai Fan Shu Wang 《Macromolecular rapid communications》2008,29(17):1489-1494
In this work, we report the design of a new multi‐functional, water‐soluble conjugated polymer integrating both a DNA intercalator and a redox label. Based on this multi‐functional conjugated polymer, we develop a sequence‐specific electrochemical DNA sensor, where the acridine unit serves as the basis for sequence discrimination, and the ferrocene label provides the electrochemical signal. Moreover, the conjugated polythiophene helps transfer electrons from ferrocene to the electrode. This sensor provides a new way for rapid and convenient detection of DNA targets.
11.
PVA/SWNT dispersions yield aloe plant‐like crystals, where the leaves are single crystals templated by PVA coated SWNT. Longer growth times (≈18 months) lead to hexagonal rod‐like crystals. HR‐TEM images show evidence that PVA molecules are aligned parallel to the SWNT axis. WAXD, electron diffraction, and HR‐TEM observations of these aloe plant and hexagonal crystals suggests evidence for possible PVA‐SWNT epitaxy. Wide‐angle and electron diffraction data of these crystals also show that the structure seems to mimic the 2D hexagonal crystal packing of SWNT. PVA lattice images and moiré fringes were also observed in the leaf‐like crystals.
12.
Lei Liu Krishna C. Etika Kang‐Shyang Liao Lance A. Hess David E. Bergbreiter Jaime C. Grunlan 《Macromolecular rapid communications》2009,30(8):627-632
Carbon nanotubes typically require the use of a dispersing or stabilizing agent to prevent significant aggregation during incorporation into a polymer matrix. These additives must be strongly associated, either covalently or physically, to achieve their purpose. In this study, multi‐walled carbon nanotubes (MWNTs) were dispersed into an epoxy matrix using polyethylenimine (PEI) as a dispersant that was either covalently attached to the nanotubes or physically mixed to result in only noncovalent interaction. Epoxy composites containing covalently modified MWNTs exhibited greater storage modulus and reduced electrical conductivity.
13.
Yunze Long Lijuan Zhang Yongjun Ma Zhaojia Chen Nanlin Wang Ze Zhang Meixiang Wan 《Macromolecular rapid communications》2003,24(16):938-942
Camphor sulfonic acid (CSA) doped polyaniline (PANI) nanotubes (175 nm in outer diameter and 120 nm in inner diameter) were synthesized successfully by a self‐assembly method. It is found that the room‐temperature conductivity of an individual PANI nanotube is 30.5 S · cm−1; in particular, the intrinsic resistance of an individual nanotube (30 kΩ) is much smaller than the contact resistance of crossed nanotubes (500 kΩ).
14.
Matthew T. Hunley Petra Ptschke Timothy E. Long 《Macromolecular rapid communications》2009,30(24):2102-2106
Nanoscale fibers with embedded, aligned, and percolated non‐functionalized multiwalled carbon nanotubes (MWCNTs) were fabricated through electrospinning dispersions based on melt‐compounded thermoplastic polyurethane/MWCNT nanocomposite, with up to 10 wt.‐% MWCNTs. Transmission electron microscopy indicated that the nanotubes were highly oriented and percolated throughout the fibers, even at high MWCNT concentrations. The coupling of efficient melt compounding with electrospinning eliminated the need for intensive surface functionalization or sonication of the MWCNTs, and the high aspect ratio as well as the electrical and mechanical properties of the nanotubes were retained. This method provides a more efficient technique to generate one‐dimensional nanofibers with aligned MWCNTs.
15.
Seok‐Ho Hwang Pingshan Wang Charles N. Moorefield Jae‐Chang Jung Jeong‐Yeol Kim Sang‐Won Lee George R. Newkome 《Macromolecular rapid communications》2006,27(21):1809-1813
Summary: An O‐hexyl‐3,5‐bis(terpyridine)phenol ligand has been synthesized and transformed into a hexagonal Zn(II)‐metallomacrocycle by a facile self‐assembly procedure capitalizing on terpyridine‐Zn(II)‐terpyridine connectivity. The structural composition was confirmed by NMR and mass spectral techniques; photo‐ and electroluminescence properties were also investigated. The OLED device shows green electroluminescent emission at 515 nm with a maximum luminance of 39 cd · m−2 and maximum efficiency of 0.16 cd · A−1.
16.
Xiaoming Yang Zhengxi Zhu Tingyang Dai Yun Lu 《Macromolecular rapid communications》2005,26(21):1736-1740
Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in‐situ polymerization. During the process fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self‐degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures.
17.
He Li Di Qiang Wang Hua Lin Chen Bai Ling Liu Li Zhen Gao 《Macromolecular bioscience》2003,3(12):720-724
This letter focuses on the first result of the preparation and the swelling behavior of a novel hybrid gelatin hydrogel with carbon nanotubes. A novel hybrid gelatin hydrogel with carbon nanotubes was synthesized by a physical mixing method. The structure of the novel hydrogel obtained was characterized by SEM. Besides, the swelling behavior of the synthesized hydrogel was measured at two different temperatures. The results indicate that carbon nanotubes added could maintain the stability of the hybrid hydrogel without cross‐linking at 37 °C. This suggests that the hybrid gelatin hydrogel with carbon nanotubes could be used in biomedical field. Besides, its application in protein separation is discussed.
18.
Roberto Napolitano 《Macromolecular theory and simulations》2006,15(8):614-618
Summary: A comparison between the crystal structure of isotactic cis‐1,4‐poly(1,3‐pentadiene) previously predicted by molecular mechanics calculations and that successively determined by other authors by experimental data is reported. The agreement between the two structures is very good as far as the space group, the unit cell parameters and the conformation of the polymer chain are concerned. The mode of packing of the chains proposed in the experimental crystal structure is very similar to that found as relative minimum in the previous energy calculations. The coexistence, in different amounts, of these two modes of packing is suggested by the analysis of the simulated X‐ray spectra and by the results of new energy calculations.
19.
Wilfrid Nri Maryse Maugey Pierre Miaudet Alain Derr Ccile Zakri Philippe Poulin 《Macromolecular rapid communications》2006,27(13):1035-1038
Summary: Fibers and yarns are promising forms to use and control the spatial orientation of carbon nanotubes in macroscopic materials. Various approaches have been proposed in the last few years to achieve fibers with a fraction of carbon nanotubes. Among them, coagulation spinning in aqueous media has proven to be a simple and capable method of leading to super‐tough materials. However, all water‐based processes described so far have made use of surfactant‐stabilized carbon nanotubes. In the present work, a method is shown to spin fibers from surfactant‐free nanotube solutions while preserving an all water‐based process. The resultant fibers exhibit mechanical and electrical properties that compare well with those of previously reported fibers spun with surfactants. The fibers exhibit a significant toughness and a high electrical conductivity.
20.
Petra Ptschke Nicolas Peer Zschoerper Bjrn P. Moller Uwe Vohrer 《Macromolecular rapid communications》2009,30(21):1828-1833
Multiwalled carbon nanotubes in the form of bucky papers were modified using Ar/O2 plasma and thereafter melt‐mixed into polycarbonate. The effect of plasma modification on the nanotubes was followed by XPS, indicating the formation of carboxylic or ester groups at the nanotube surfaces. In the melt‐mixed nanocomposites, the modified nanotubes exhibited a better macrodispersion and better phase adhesion to the matrix as evidenced by morphological investigations. The electrical percolation threshold was not altered and occurred below 0.5 wt.‐% nanotubes. The mechanical properties were improved by having higher values of stress at yield, stress beyond the yield point, and strain at break illustrating the effect of both better dispersion and enhanced phase adhesion.