Polyurethane (PU) foam is known as the popular material for the applications in many fields of industry and life. To improve the mechanical and thermal properties of this material, in this research, PU foam was reinforced with aniline-modified multiwalled carbon nanotubes (MWCNTs). Fourier transform infrared FTIR spectrum of modified MWCNTs showed the aniline was grafted on the surface of MWCNTs through the appearance of –NH2 stretches. The effect of MWCNTs with and without modification on the density, porosity, compressive strength, and heat conductivity of PU/MWCNT foam nanocomposites was investigated. The dispersibility of MWCNTs in the PU matrix was enhanced after modification with aniline. Compressive strength of PU nanocomposite reached the highest value after adding 3 wt.% of modified MWCNTs into PU foam. Besides, the water uptake of PU nanocomposites using 3 wt.% of MWCNTs was decreased to 13.4% as compared to that using unmodified MWCNTs. The improvement in thermal conductivity of PU/aniline-modified MWCNT nanocomposite was observed due to the change in the cellular size of PU foam in the presence of MWCNTs as shown by SEM images.
An opalic plasmonic sample, constituted by a hexagonal arrangement of metallized silica spheres, presents remarkableoptical properties due to the mixing of periodic arrangement and singularities at the sphere touching points. It is therefore an interesting candidate for exploiting the excitation of both localized and propagating surface plasmons. Several channels of excitation based on these properties orexploitinga certain level of disorder are evidenced, openingnew routes for the efficient excitation of plasmons on a wide spectral range. The versatility of such hybrid system is evidenced in the context of two complementary experiments: specular reflective spectrometry and photoemission electron microscopy. Both techniques offer different points of view on the same physical phenomenon and the link between them is discussed. Such experiments evidence the opportunities offered by these 2D hybrid materials in the context of nanophotonics.Keywords: opal, localized surface plasmon, surface plasmon polariton,specular reflectometry, photoemission electron microscopy (PEEM)Engineering the density of states is a key issue in nanophotonics for controlling and manipulating the interaction between light and matter. Passive devices like waveguides as well as active ones like light nanosources require the manipulation of the density of states in volume or on surface.Photonic crystals are well known for the engineering of the Q factor. In 2D structures high Q factors are obtained in connection to the use of high contrast index materials 1, 2, 3, 4, 5 . In3D,photonic crystalsare usually fabricated with low-index materials yielding tolower Q factors.However, laserinduced lithographic crystals 6, 7 or self-assembled artificial opals 8,9,10 have permitted the engineering of the density of states 11 ,leading to a reinforcement of the light-matter interaction for emitters inserted in these structures 12,13,14,15 .Despite the limitation in achievable Purcell factors in low-Q cavities, a modification of emission rate has been evidenced 16,17 . A major characteristic of low-Q nanostructures is that they are much less demanding in terms of spectral matching. They offer a high versatility in the spectral tuning of the devices which isa major advantage for applications. Another strategy for increasing the interaction between light and matter, is not only to play with the Q factor, but also with the spatial confinement of the mode. Therefore plasmonic devices offering the opportunity to obtain intense fields in a very small volume are very good candidates for tuning the emission. An acceleration of the spontaneous emission in various antenna devices has been evidenced 18,19,20,21 as well as an increase in the photon extraction 22,23,24 .Moreover, the versatilityof
Opal-based photonic crystals are promising materials to engineer complex heterostructures for efficient manipulation of nano-emitters fluorescence. We fabricated and characterized a structure composed of a layer of silica embedded between two silica opals. Thanks to this controlled planar defect which opens a permitted frequency band in the photonic stopband, an 10 increase of emission, depending on angular distribution, is evidenced through photoluminescence spectroscopy. We discuss the use of such a structure as a self-assembled micrometer-sized spectroscopic device and demonstrate that it can be used to point the maximum emission wavelength of an unknown light source up to a certain linewidth. It can as well separate two sources, emitting at different wavelengths, with a resolution given by the 15 Rayleigh criterion.
This report presents the effect of synthesis conditions on the synthesis of graphene nanosheets via electrochemical exfoliation method for adsorbing methylene blue from aqueous solution. Oxygen-containing functional groups and defects in the material were characterized by Raman and X-ray photoelectron spectroscopy (XPS). As a result, by using voltage of 15 V, (NH4)2SO4 (5%, 250 mL) and KOH (7.5%, 250 mL), the obtained material showed the highest MB adsorption capacity due to the high densities of oxygen-containing groups and defects comparison to other conditions.
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