共查询到20条相似文献，搜索用时 0 毫秒
1.
H. Wang Y. Wang X. Zhou L. Zhou J. Tang J. Lei C. Yu 《Advanced functional materials》2007,17(4):613-617
By employing commercial poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) block copolymers as templates in near‐neutral aqueous solutions in the absence of organic cosolvents, unilamellar siliceous vesicles and nanofoams with ultrahigh pore volumes (> 3 cm3 g–1) are successfully synthesized. At controlled pH, a tubular micelle → unilamellar vesicle → nanofoam structural transformation is observed by increasing the reaction temperature. It is proposed that the siliceous vesicles are synthesized via a co‐operative block‐copolymer vesicle templating approach, while the siliceous nanofoams are obtained by the fusion of vesicles at increased ionic strength. Compared to literature methods to synthesize siliceous vesicles and foams, our method is convenient, cheap, and produces a high yield. Siliceous nanofoams synthesized by using our approach show superior bioimmobilization capacity over other porous materials for biomolecules with large molecular weight. 相似文献
2.
E. Palacios‐Lidn B. Perez‐García J. Abelln C. Miguel A. Urbina J. Colchero 《Advanced functional materials》2006,16(15):1975-1984
Mixtures of poly(3‐octylthiophene) (P3OT) with graphite nanoparticles have been investigated by scanning force microscopy (SFM) techniques. The morphology as well as the mechanical and electrical properties of the blends has been characterized at the nanoscale level as a function of the carbon nanoparticle content in the blend. An increase in the concentration of carbon nanoparticles results in an increase in the surface roughness of the blend and the appearance of distinct regions with well‐defined electrical and mechanical properties. At intermediate concentrations (5–10 wt % of carbon nanoparticles), the samples show pure P3OT regions, as well as round regions containing a mixture of the polymer and carbon nanoparticles, while at higher concentrations (> 15 wt %), the entire sample is composed of this mixture. The interface between the two regions has been studied by electrostatic scanning force microscopy (ESFM) as a function of the applied tip–sample voltage. ESFM provides evidence for the creation of new electronic states at the heterojunction. The observed results can be qualitatively explained in terms of the electronic properties of the individual molecular components, P3OT, functionalized graphite nanoparticles, and their corresponding heterojunction. The implications of these results for organic polymer solar cells are also discussed. 相似文献
3.
W. H. Binder L. Petraru T. Roth P. W. Groh V. Pálfi S. Keki B. Ivan 《Advanced functional materials》2007,17(8):1317-1326
Supramolecular gels consisting of trivalent polyisobutylene and bivalent poly(ethylene oxide) are generated. Strong hydrogen bonding interactions, affixed to the end‐group moieties of the respective polymers (binding constant Kassn = 105 M –1), serve as molecular glue, leading to the formation of weak gels. Two different gels were prepared: one, with a short telechelic poly(ethylene glycol) (PEG) segment (gel A), and one with a longer PEG segment (number‐average molecular weight Mn = 2000 g mol–1) (gel B). Both gels show a significant increase in viscosity upon mixing of the two polymeric components, with a lag time of several minutes, indicative of nucleation mechanisms as the formation principle. However, only gel A displays classical gel‐like behavior, with a loss modulus G′ larger than the storage modulus G″ after formation. Both gels display microphase‐separated behavior with a spacing between 4–5 nm as probed via small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. The incorporation of magnetic nanoparticles (Fe2O3; radius r = 3.5 nm) is successfully achieved, generating new magnetic gels with strongly thermoresponsive properties, displaying a strong temperature‐dependent release profile of included dye molecules. Magnetic measurements indicate a superparamagnetic behavior of the incorporated nanoparticles, prospecting the application as magneto‐sensitive delivery gels for pharmaceutical purposes. 相似文献
4.
V. Palermo G. Ridolfi A. M. Talarico L. Favaretto G. Barbarella N. Camaioni P. Samorì 《Advanced functional materials》2007,17(3):472-478
Light‐induced generation of charges into an electron acceptor–donor phase‐segregated blend is studied. The blend is made of highly ordered nanoscopic crystals of 3″‐methyl‐4″‐hexyl‐2,2′:5′,2″:5″,2?:5?,2″″‐quinquethiophene‐1″,1″‐dioxide embedded into a regioregular poly(3‐hexylthiophene) matrix, acting as acceptor and donor materials, respectively. Kelvin probe force microscopy investigations reveal a tendency for the acceptor nanocrystals to capture the generated electrons whereas the donor matrix becomes more positively charged. The presence of particular positively charged defects, i.e., nanocrystals, is also observed within the film. The charging and discharging of both materials is studied in real time, as well as the effect of different acceptor–donor ratios. Upon prolonged thermal annealing at high temperatures the chemical structure of the blend is altered, leading to the disappearance of charge separation upon light irradiation. The obtained results allow a better understanding of the correlation between the nanoscopic structure of the photoactive material and solar‐cell performance. 相似文献
5.
一种新型的STM探针 总被引：2，自引：0，他引：2
以普通的石英光纤为材料,用熔拉腐蚀复合的方法制备出nm量级的光纤探针,而后在针尖表面镀上数十nm厚的金属膜,达到导电性,使其能传导隧道电流,从而研制出一种新型的扫描隧道显微镜（STM）光纤隧道探针,在STM上取得了比较理想的实验结果。本文将光纤隧道探针与金属隧道探针作了比较,并对其性能作了分析。 相似文献
6.
D. Blond V. Barron M. Ruether K.&#x;P. Ryan V. Nicolosi W.&#x;J. Blau J.&#x;N. Coleman 《Advanced functional materials》2006,16(12):1608-1614
Poly(methyl methacrylate) (PMMA)‐functionalized multiwalled carbon nanotubes are prepared by in situ polymerization. Infrared absorbance studies reveal covalent bonding between polymer strands and the nanotubes. These treated nanotubes are blended with pure PMMA in solution before drop‐casting to form composite films. Increases in Young's modulus, breaking strength, ultimate tensile strength, and toughness of ×1.9, ×4.7, ×4.6, and ×13.7, respectively, are observed on the addition of less than 0.5 wt % of nanotubes. Effective reinforcement is only observed up to a nanotube content of approximately 0.1 vol %. Above this volume fraction, all mechanical parameters tend to fall off, probably due to nanotube aggregation. In addition, scanning electron microscopy (SEM) studies of composite fracture surfaces show a polymer layer coating the nanotubes after film breakage. The fact that the polymer and not the interface fails suggests that functionalization results in an extremely high polymer/nanotube interfacial shear strength. 相似文献
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Annalisa Bonfiglio Rita Paradiso Ermanno Di Zitti Davide Ricci Alberto Bolognesi William Porzio 《Advanced functional materials》1993,2(6):295-299
The self-assembly technique experimented for the deposition of alkanes and alkyl derivatives on layered compounds at the liquid/solid interface has been successfully extended to the adsorption of poly(3-decyl-thiophene) on graphite. The molecular films so obtained have been investigated using scanning tunnelling microscopy (STM). Images taken in both the constant-current and constant-height modes show highly packed arrays of molecules characterised by an average length and an average spacing that are in good agreement with results obtained by X-ray diffraction investigations. Constant-current images allow one to observe domain formations in preferential directions coincident with the main axes of the graphite lattice, while constant-height imaging, performed on small areas, allows one to resolve atomic structures within the polymer backbone. In particular, periodic, 0.71 nm spaced features have been identified along the side of the polymer backbone; they can be associated with the length of two monomer units and are attributable to imaging of sulphur atoms in the backbone. 相似文献
10.
Patrick W. Leech Brett A. Sexton Russell J. Marnock 《Microelectronic Engineering》2002,60(3-4):339-346
The fine-scale features of optically variable devices (OVDs) fabricated in resist by electron beam lithography have been examined using scanning probe microscopy (SPM). These features have included patterns of gratings, micro-text and geometrical images. Scanning probe microscopy has provided information on the groove angle, depth of profile and spatial frequency of the features as determined by the details of processing of the image. The OVD patterns formed in EBR-9 and X-AR-P 7400 resists exhibited a more rounded profile with a lower side-wall angle than in ZEP-7000 and PMMA resists. 相似文献
11.
J.&#x;N. Coleman M. Cadek R. Blake V. Nicolosi K.&#x;P. Ryan C. Belton A. Fonseca J.&#x;B. Nagy Y.&#x;K. Gun'ko W.&#x;J. Blau 《Advanced functional materials》2004,14(8):791-798
Polymer–multiwalled carbon nanotube composite films were fabricated using two types of polymer matrices, namely poly(vinyl alcohol), (PVA) and chlorinated polypropylene. In the first case, the PVA was observed to form a crystalline coating around the nanotubes, maximising interfacial stress transfer. In the second case the interface was engineered by covalently attaching chlorinated polypropylene chains to the nanotubes, again resulting in large stress transfer. Increases in Young's modulus, tensile strength, and toughness of × 3.7, × 4.3, and × 1.7, respectively were observed for the PVA‐based materials at less than 1 wt.‐% nanotubes. Similarily for the polypropylene‐based composites, increases in Young's modulus, tensile strength and toughness of × 3.1, × 3.9, and × 4.4, respectively, were observed at equivalent nanotube loading levels. In addition, a model to describe composite strength was derived. This model shows that the tensile strength increases in proportion to the thickness of the interface region. This suggests that composite strength can be optimized by maximising the thickness of the crystalline coating or the thickness of the interfacial volume partially occupied by functional groups. 相似文献
12.
M. Surin D. Marsitzky A.&#x;C. Grimsdale K. Müllen R. Lazzaroni P. Leclre 《Advanced functional materials》2004,14(7):708-715
In this paper, we describe the synthesis and characterization of poly(9,9′‐dioctylfluorene)–poly(ethylene oxide) (PF‐PEO) block copolymers with different block ratio and molecular architectures (diblock or triblock copolymers). Tapping‐mode atomic force microscopy is used to investigate the relationship between the molecular structure and the microscopic morphology of thin deposits. Copolymers with a low average volume ratio of PEO (fEO from 0.1 to 0.3) exhibit a well‐defined organization into nanoribbons. A model of chain packing is proposed; these structures arise from the interplay of π–π interactions between conjugated PF segments and the interactions of PEO with the mica substrate surface. For copolymers with higher average volume ratio of PEO (fEO > 0.4), the organized structures disappear and lead to untextured aggregates, probably because long‐range, regular π–π stacking of the segments can no longer take place. We also observe that the nature of the solvent from which deposits are grown and the substrate polarity have a strong impact on the microscopic morphology. 相似文献
13.
A novel, three-phase, double-percolating composite with NiZn-ferrite particles and nickel particles embedded in a poly(vinylidene fluoride) matrix is prepared by a simple hot-pressing method. Large ferrite particles in the composite not only act as a magnetic phase, thus endowing the composite with a high initial permeability, but also present (in a high volume fraction) a discrete (non-percolating) phase, confining polymer and metallic particles into a continuous double-percolating structure of low volume fraction. In particular, a large enhancement in both the initial permeability and the dielectric constant of the three-phase composites is observed, which is due mainly to the addition of a small number of nickel particles that act as both magnetic and percolative metallic phases. The dielectric and magnetic behavior observed in the three-phase composites can be explained by effective-medium and percolation theories. 相似文献
14.
J.‐M. Kim Y.&#x;B. Lee S.&#x;K. Chae D.&#x;J. Ahn 《Advanced functional materials》2006,16(16):2103-2109
Poly(vinyl alcohol) (PVA) films embedded with functional polydiacetylene (PDA) are efficiently prepared for color and fluorescence imaging. Intensely blue films are obtained by mixing and drying solutions containing PDA vesicles and PVA. A blue‐to‐red color transition is observed upon heating the polymer films. In addition, selective UV irradiation (through a photomask) of PVA films containing diacetylene monomer results in the generation of micropatterned color (without heating) and both color and fluorescent images (after heating the films at 120 °C for 10 s). Patterned two‐color (blue and red) images in the polymer film are readily obtained by a sequential process of photomasked irradiation, heating, and unmasked irradiation. 相似文献
15.
Extensive research efforts are devoted into seeking the thermally and mechanically durable dielectric materials for flexible electronics. In this work, a series of sulfonylated poly (phenylene ether)s (PPEs) were synthesized and served as gate dielectrics in the flexible OFET devices with crosslinked poly (2-allyl-6-methylphenol-co-2,6-dimethylphenol) (APPE) as substrate. The chemical structure, thermal, morphology, and dielectric properties were investigated, and the corresponding OFET devices were accordingly fabricated and characterized. We found that the discrepancy in sulfone content of PPE-xS renders the difference in thermal stability, surface polarity and dielectric constants. Among them, PPE-9kS with the highest sulfone content of 63% shows the best dielectric properties in the flexible OFET devices with hole mobility (μp) of 0.45 cm2 V−1 s−1, outperforming its parent polymer without sulfone group (PPE-9k) with μp of 0.14 cm2 V−1 s−1. Besides, the flexible device with PPE-9kS as dielectric exhibits highly retained device performance after cyclic bending or thermal treatment, which indicates the decent mechanical and thermal durability. The present study documents a practical methodology to fabricate a high-performance flexible OFET with excellent thermal and mechanical stability. 相似文献
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Steffen Cosson Stefan A. Kobel Matthias P. Lutolf 《Advanced functional materials》2009,19(21):3411-3419
A versatile strategy to rapidly immobilize complex gradients of virtually any desired protein on soft poly(ethylene glycol) (PEG) hydrogel surfaces that are reminiscent of natural extracellular matrices (ECM) is reported. A microfluidic chip is used to generate steady‐state gradients of biotinylated or Fc‐tagged fusion proteins that are captured and bound to the surface in less than 5 min by NeutrAvidin or ProteinA, displayed on the surface. The selectivity and orthogonality of the binding schemes enables the formation of parallel and orthogonal overlapping gradients of multiple proteins, which is not possible on conventional cell culture substrates. After patterning, the hydrogels are released from the microfluidic chip and used for cell culture. This novel platform is validated by conducting single‐cell migration experiments using time‐lapse microscopy. The orientation of cell migration, as well as the migration rate of primary human fibroblasts, depends on the concentration of an immobilized fibronectin fragment. This technique can be readily applied to other proteins to address a wealth of biological questions with different cell types. 相似文献
18.
《Mechatronics》2015
A macro-scale atomic force microscope (macro-AFM) has been designed and used for teaching precision mechatronics. The macro-AFM uses a novel electromagnetic self-sensing self-actuating probe. It operates in frequency-modulation AFM (FM-AFM) mode with intermittent contact. The AFM has an imaging volume of 250 mm × 40 mm × 1 mm with a resolution of about 1 μm at 1 Hz measurement bandwidth. The macro-AFM is simple and relatively inexpensive to build. It is scaled to make motion visible to the eye and is robust for a lab environment, all of which make it an affordable and effective educational tool. The macro-AFM is used in Mechatronics (2.737), a graduate level course at MIT, where in a series of 11 laboratory exercises, the students assembled and programmed the AFM system. This article provides the design and theory used for making and controlling the macro-AFM, as well as experimental results. 相似文献
19.
Scanning Probe Microscopy (SPM) imaging process is inherently slow, and commonly suffers from instrumental drift. According to experience, drift is a time dependent phenomenon and therefore it influences measurement results obtained using the instruments for long periods of time, e.g. when high resolution imaging is performed by taking many profiles. Evaluation and control of actuator drift is an important issue for high accuracy measurements. In particular, a better probe positioning can be obtained through characterization of the scanning system’s metrological performance, and distinguishing systematic and stochastic behavior components. In this work, a new approach is proposed to study long term thermal phenomena, correlating them to SPM scanner drift distortions evaluated using calibrated reference samples. Long term drift evaluation is then cross-correlated to thermal analyses carried out in parallel by means of an infrared-camera. Eventually, it is discussed how the investigations here presented may be used to improve the instrument set-up in order to reduce measurement uncertainty. 相似文献
20.
O. Azzaroni S.&#x;E. Moya A.&#x;A. Brown Z. Zheng E. Donath W.&#x;T.&#x;S. Huck 《Advanced functional materials》2006,16(8):1037-1042
In this work a new variation of microcontact printing is described, which is used to transfer chemical patterns onto different substrates. The approach is based on the use of conventional elastomeric stamps modified with polyelectrolyte brushes. It is demonstrated that, by using stamps modified with brushes acting as preconcentrating/sorbent nanolayers, it is possible to control the uptake of aqueous inks containing ionic species. This controlled uptake can be easily used for site‐selective delivery of the loaded species by means of soft lithography. The potential of this approach is demonstrated by creating patterned counterion domains in a flat polyelectrolyte brush and by promoting a site‐selective metallization through galvanic displacement reactions with reactive species. 相似文献