ABSTRACT
Lightweight structural materials are commonly used as effective fillers for advanced composites with high toughness. This study focused on enhancing the toughness of direct-spun carbon nanotube yarns (CNTYs) by controlling the micro-textural structure using a water-gap-based direct spinning. Drawing inspiration from the structural features of natural spider silk fibroin, characterized by an α-helix in the amorphous region and ß-sheet in the crystalline region, multiscale bundles within CNTYs are reorganized into a unique nano-coil-like structure. This nano-coiled structure facilitated the efficient dissipation of external mechanical loads through densification with the rearrangement of multiscale bundles, improving specific strength and strain. The resulting CNTYs exhibited exceptional mechanical properties with toughness reaching 250 J g-1, making them promising alternatives to commercially available fibers in lightweight, high-toughness applications. These findings highlight the significance of nano-coiling engineering for emulating bio-inspired micro-textural structures, achieving remarkable enhancement in the toughness of CNTYs.
ABSTRACT
Fiber-type solid-state supercapacitors are being widely investigated as stable power supply for next-generation wearable and flexible electronics. Integrating both high charge storage capability and superior mechanical properties into one fiber is crucial to realize fiber-type solid-state supercapacitors. In this study, we design a "jeweled necklace"like hybrid composite fiber comprising double-walled carbon nanotube yarn and metal-organic frameworks (MOFs). Subsequent heat treatment transforms MOFs into MOF-derived carbon (MDC), thereby maximizing energy storage capability while retaining the superior mechanical properties. The hybrid fibers with tunable properties, including thickness and MDC loading amount, exhibit a high energy density of 7.54 milliwatt-hour per cubic centimeter at a power density of 190.94 milliwatt per cubic centimeter. The mechanical robustness of the hybrid fibers allows them to operate under various mechanical deformation conditions. Furthermore, it is demonstrated that the resulting superstrong fiber delivers sufficient power to switch on light-emitting diodes by itself while suspending 10-kilogram weight.
ABSTRACT
We developed a new category of porous silica and organosilicas nanostructures in a facile method based on weakly acidic aqueous-ethanol media by utilizing two different pentablock copolymer templates of type PLGA-PEO-PPO-PEO-PLGA. Pluronic block templates were used mainly to prepare these pentablock copolymers with different molecular weights and volume ratios. Silica precursor tetraethyl orthosilicate and organosilicas precursor 1,4-bis(triethoxysilyl)benzene have been used as main source for synthesizing the silica and organosilicas samples. Weak Lewis acids iron(III) chloride hexahydrate, aluminum(III) chloride hexahydrate, and boric acid were utilized as catalyst instead of any strong inorganic acids and the molar ratio of catalyst/precursor has been optimized to 1-2 for preparation of ordered mesostructures. Reaction temperatures have been optimized to 25 °C for pure silica and both 25 °C as well as 40 °C for organosilicas to get the best result for mesostructures. A detailed analysis by using various analytical techniques like synchrotron small angle X-ray scattering, nitrogen sorption, transmission electron microscopy, scanning electron microscope, solid-state 29Si CP-MAS nuclear magnetic resonance (NMR), and so on has revealed well developed mesostructures with surface area of 388-836 m2/g for silica and 210-691 m2/g for organosilica samples, respectively. Furthermore, bimodal typepores have been observed from pore size distribution plot of the samples. Thermal stability of the materials was up to 400 °C as analyzed by thermogravimetric analysis.
ABSTRACT
It is of importance to explore a new carbon nanomaterial possessing vital functions to fulfill the high standards for practical achievement of the electromagnetic (EM) barrier for blocking EM waves and the electrochemical (EC) barrier as a functional separator for EC energy storage. Herein, facile synthesis of a new class of carbon nanostructures, which consist of interconnected N-doped graphitic carbon nanocubes partially embedded by nickel nanoparticles, is described. The hollow interior of graphitic nanocube induces internal reflection of EM waves and confines active materials of EC energy storage. Nitrogen functionalities implanted in graphitic structure enhance electrical conductivity as well as improve chemical interaction with active materials. Furthermore, nickel nanoparticles in graphitic nanocube function as an EM wave-absorbing material and an electrocatalyst for EC energy storage. Through comprehensive assessments, remarkable performances originating from distinctive nanostructures give new insights into structural design for the carbon nanostructure-based high-performance EM and EC barriers.
