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Polyaniline-decorated reduced graphene oxide/ferrite nanofiller (RGPF) prepared by the solution mixing method in three different ratios (1 : 3, 1 : 1 and 3 : 1) of polyaniline-decorated reduced graphene oxide and ferrite have been studied for microwave absorption properties in defence application. The polyaniline-decorated reduced graphene oxide/ferrite and neat ferrite nano-fillers have been used for the preparation of an epoxy nanocomposite (RGPFE) of 60 wt%. The distribution of the RGPF nanofiller in the epoxy matrix was analyzed by field emission scanning electron microscopy. Further, thermal gravimetric analyses revealed the excellent thermal stability of the nanocomposites. A vibrating sample magnetometer was employed to find out the magnetic behavior of the prepared nanocomposites. The complex permittivity and permeability were investigated to evaluate the principal properties in the frequency range from 2 to 18 GHz. These results show that an epoxy nanocomposite with 60 wt% RGPF filler in the ratio of 3 : 1 has maximum dielectric loss. Finally, these electromagnetic data were used to calculate the reflection loss of the epoxy nanocomposites, and showed good agreement between the calculated and measured data of these nanocomposites. The minimum reflection loss was observed as -10.26 dB in the X band with a thickness of 3.0 mm, and the bandwidth was 8.47 GHz for RL ≤-10 dB. On the basis of the above observations, these nanocomposites could be a good candidate for electromagnetic interference shielding (EMI) and microwave absorption applications.

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The presence of low-dimensional functional nanofillers during the formation of morphological phase boundaries in polymeric nanofibers by electrospinning was highlighted in this study. PAN and TPU were both selected with differential viscosities to understand the phase-segregated internal supramolecular structures on functional surfaces of different length scales. The low-dimensional carbon nanofillers displayed a significant role in the topological orientation of the polymeric chains in TPU due to the presence of hard and soft segments in the geometry of TPU. The nano-hybrid shish-kebab-type microphase separation was observed on 1D nanofillers, whereas the anisotropic hierarchical microdomains were formed in the presence of 0D nanofillers. The 2D functional surface produced highly folded nanoscale lamellae by molecular interactions with polymeric chains. By combining different dimensional nanofillers, the hybrid 1D-2D networks created multifaceted structural hierarchies with epitaxial growth on the planar surface and shish-kebab geometry on the 1D functional backbone. Our study has demonstrated the significance of the configuration of nanoscale functional surfaces on the texture of polymeric chain assemblies during electrospinning for controlled flexible scaffolds.

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Micron long carbon nanofibers (CNFs) were grown on porous carbon beads to give an active surface for rapid immobilization of guest molecules. The fabrication of nanostructures using a catalytic route involving chemical vapour deposition on a porous substrate was accomplished by the controlled synthesis of iron nanoclusters on the surface of porous carbon beads. The challenge of catalyst nanoparticle diffusion into the porous substrate was addressed by using iron coordinated ligand complexes and optimizing the loading percentage of metal salts onto beads. The effect of using tethered bottom up surface processed CNFs on the porous beads' morphologies was established using structural characterization. The protruding architecture of CNFs on the porous carbon surface was subjected to bacterial colonisation in order to determine the efficiency of cell conjugation onto hairy structures, particularly at a low concentration. The interfaces of immobilized bacteria on the textured surface were studied by varying the pH and external physical stimuli to check the biofilm formation. The strategy of fabricating all carbon porous beads, which had topologically controlled 'nano on micro' geometries, to give fast immobilization of guest molecules could be useful in the future for developing an active disinfectant surface.

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This study is aimed to represent the role of carbonaceous nanofillers to reinforce the commercially available polyurethane porous structure. The effect of dimensionality of fillers to anchor the construction of stable three-dimensional (3D) cellular architectures has been highlighted. The cellular frameworks of commercially available thermoplastic polyurethane (TPU) have been fabricated through the thermoreversible supramolecular self-assembly route. It was established that the minimum shrinkage of TPU lattice structures occurred when the solid-state network is strengthened by the topologically engineered 3D hierarchical nanofillers, where the amount of reinforcement was found to play a critical role. It has been established by series of structure-property correlations that reinforcing the cellular structure to endure the capillary stress is equally effective as supercritical drying for producing low-density porous morphologies. The removal of liquid phase from gel is as important as the presence of 3D fillers in the matrix for reinforcing the cellular structures when replacing the solvent phase with air to generate a two-phase solid-gas engineered morphology. The insight into the polyurethane network structure revealed that the dimensionality, amount, and distribution of fillers in the matrix are critical for reinforcing the cellular scaffolds in solid gel without any cross-linking.

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The interfacial debonding of graphite lattices using iron (Fe) nanoparticles and Fenton's reagent is reported, towards the scalable production of few-layer graphene flakes. Acoustic cavitation via a sonochemical route was adapted to produce iron and iron oxide nanoparticles in the graphite matrix. The oxygenated species were introduced into the graphite lattice using a physical method, and then Fenton chemistry was utilized to generate localized hydroxyl radicals at the Fe nanoparticle-graphite interfaces for zipping and self-exfoliation of the defected graphite lattices. The functional groups were found to have been introduced predominately at the periphery of the flake, confirming that the lateral dimension of graphene had not been affected, and at the same time, good dispersion in organic solvents had been achieved. Defect engineering could be modulated at the organic-inorganic hybrid interfaces, in order to control the zipping rate and regulate the degree of functionalization and the lateral dimensions of the graphene sheet.

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We have investigated the agglomeration behaviour of two types of multi-walled carbon nanotubes (MWNTs; N-MWNTs and D-MWNTs), which have different chemical functionalities, average diameter, varying extent of agglomeration and agglomerations. The properties were altered by varying the agglomerated structure. The strength of the MWNT agglomerates was estimated via nanoindentation. The work done to indent D-MWNT agglomerates (3910.3 × 10(-8) erg) was higher than for N-MWNTs agglomerates (2316.4 × 10(-8) erg). An organic modifier, the Li salt of 6-aminohexanoic acid (Li-AHA), was used to deagglomerate the MWNTs in an aqueous medium. The stability of the aqueous dispersion of Li-AHA-modified MWNTs was analyzed by UV-vis spectroscopy and zeta potential measurements. An increase in Li-AHA concentration increased the dispersion of MWNTs in the aqueous medium. Furthermore, the mechanism of dispersion of the two types of MWNTs in the aqueous medium in the presence of Li-AHA was determined based on the electrostatic charge repulsion between the negatively charged species. A fluorescence-activated cell sorting technique was used to assess the debundling of MWNT agglomerates in the aqueous medium. We examined the morphology-property relationship in Li-AHA-modified MWNTs.

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Carbon microcoils are generally prepared by catalytic chemical vapor deposition of acetylene, using Ni as the catalyst and thiophene as the promoter. In this work, a new catalyst has been developed on purpose to avoid the introducing of noxious and unpleasant thiophene during the reaction process. The products obtained at temperature of 740 degrees C were pure, regular and had perfect morphology. Scanning electron microscopy and Raman spectroscopy were employed to characterize the asprepared carbon microcoils.

RESUMEN

An effective method of growth by catalytic chemical vapor deposition (CCVD) to get a large-scale yield of carbon nanotubes is reported. In this method, acetylene is decomposed catalytically over well-dispersed metal particles (Co-Fe and Co-Ni) embedded in commercially available zeolite at a lower temperature (600-700 degrees C). The two binary-metal catalysts (Co-Fe and Co-Ni) used are compared by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Crucial reaction parameters, such as reaction time, temperature, and the effect of purity of gas to obtain optimum production of the nanotubes, both qualitatively and quantitatively, are also reported.

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