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Research Article Issue
Large-area ultrastrong and stiff aramid nanofiber based layered nanocomposite films
Nano Research 2024, 17 (2): 829-835
Published: 13 October 2023
Downloads:150

One-dimensional (1D) aramid nanofiber (ANF) based nanocomposite films have drawn increasing attentions in various applications due to their excellent mechanical properties and impressive chemical and thermal stabilities. However, the large-area fabrication of aramid nanocomposite films with ultrastrong mechanical properties under mild conditions remains a great challenge. Here we present a facile superspreading-assisted strategy to produce aramid nanofiber based oriented layered nanocomposites using phase inversion process that occurs at the fully swollen hydrogel surfaces. The nanocomposite films based on ANF, carboxylation carbon tube (CNT–COOH), poly(vinyl alcohol) (PVA), and MXene nanosheet exhibit a tensile strength of up to 870.8 ± 85 MPa, a Young’s modulus of 21.8 ± 2.2 GPa, and outstanding toughness (up to 43.2 ± 4.6 MJ/m3), which are much better than those conventional aramid nanofiber based materials. Electrical conductivity of our nanocomposite films reaches the maximum of about 1100 S/m. The fabulous mechanical properties combination and continuous production capability render our strategy representing a promising direction for the development of high-performance nanocomposites.

Research Article Issue
Continuous preparation of strong and tough PVA nanocomposite fibers by mechanical stretching-assisted salting-out treatment
Nano Research 2024, 17 (4): 3156-3163
Published: 13 September 2023
Downloads:115

Polymer composite fibers with superior properties such as excellent combined strength and toughness and biocompatibility can be used in high-tech applications of braided protective devices and smart wearable, however the research of high-performance polymer composite fiber remains in the infant stage. Here we present a strategy to produce strong and tough anisotropic polymer nanocomposite fibers with orientedly aligned salt rods using mechanical stretching-assisted salting-out treatment. The prepared nanocomposite fibers have a tensile strength of up to 786 ± 2.7 MPa and an elongation at break of 81%, and the anisotropic fibers exhibit good transmission of mechanical vibration in the longitudinal direction with high resolution. During the fabrication process, the salt builds up into oriented rods during the directional salting process, and the polymer is confined to the 150 nm domain between the rods after the solvent is completely evaporated, giving the nanocomposite fibers superior mechanical properties. The presented strategy can be applied to the continuous mass production of nanocomposite fibers and is also generalizable to other polymer nanocomposites, which could extend the applicability of nanocomposite fibers to conditions involving more demanding mechanical loading and mechanical vibration transmission.

Research Article Issue
Amphiphilic Pd@micro-organohydrogels with controlled wettability for enhancing gas–liquid–solid triphasic catalytic performance
Nano Research 2022, 15 (1): 557-563
Published: 22 June 2021
Downloads:21

The wettability of catalyst plays an important role in regulating catalytic performance in heterogenous catalysis because the microenvironment around the catalytic sites directly determines the mass transfer process of reactants. Inspired by gas trapped on the surface of subaquatic spiders, amphiphilic micro-organohydrogels with tunable surface wettabilities were developed by anchoring various alkane chains onto a poly(2-(dimethylamino)ethyl methacrylate) (p(DMAEMA)) hydrophilic microgel network. Palladium nanoparticles (Pd NPs) were encapsulated in amphiphilic microgels (amphiphilic Pd@M) to catalyze hydrogenation reaction, achieving higher activities than pristine monohydrophilic Pd@M composite. The underwater oleophilicity and aerophilicity of Pd@M composites were quantified by oil/gas adhesion measurements and computational simulations. The higher amphiphilic catalytic activities are attributed to the formation of a gas–oil–solid reaction interface on the catalyst surfaces, allowing rapid transport of H2 and organic substrates through water to the Pd catalytic sites. Additionally, amphiphilic Pd@M composites also exhibit more superior catalytic performance in multi-substrates reaction.

Research Article Issue
Magnetic-programmable organohydrogels with reconfigurable network for mechanical homeostasis
Nano Research 2021, 14 (1): 255-259
Published: 05 January 2021
Downloads:36

Synthetic materials with tunable mechanical properties have great potential in soft robotics and biomedical engineering. However, current materials are limited to the mechanical duality altering their mechanical properties only between soft and hard states and lack of consecutively programmable mechanics. Herein, the magnetic-programmable organohydrogels with heterogeneous dynamic architecture are designed by encasing oleophilic ferrofluid droplets into hydrogel matrix. As magnetic field increases, the mechanical properties of organohydrogels can be consecutively modulated owing to the gradual formation of chain-like assembly structures of nanoparticles. The storage modulus G′ increases by 2.5 times when magnetic field goes up to 0.35 T. Small-Angle X-ray Scattering (SAXS) confirms the reconfigurable orientation of nanoparticles and the organohydrogels show reversible modulus switching. Besides, the materials also exhibit high stretchability, magnetic actuation behavior and effective self-healing capability. Furthermore, the organohydrogels are applied into the design of effectors with mechanical adaptivity. When subjected to serious external perturbations, the effector can maintain mechanical homeostasis by regulating modulus of organohydrogel under applied magnetic field. Such materials are applicable to homeostatic systems with mechanically adaptive behaviors and programmed responses to external force stimuli.

Research Article Issue
Hierarchical structures hydrogel evaporator and superhydrophilic water collect device for efficient solar steam evaporation
Nano Research 2021, 14 (4): 1135-1140
Published: 19 November 2020
Downloads:28

Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials. Conventional strategies are focused on the development of the composition and structure of the hydrogel’s internal network. In our point of view, the importance of the surface structure of hydrogel has usually been underestimated or ignored. Here inspired by the excellent absorbance and water transportation ability of biological surface structure, the hierarchical structured hydrogel evaporators (HSEs) increased the light absorption, trapping, water transportation and water-air interface, which is the beneficial photothermal conversion and water evaporation. The HSEs showed a rapid evaporation rate of 1.77 kg·m−2·h−1 at about 92% energy efficiency under one sun (1 kW·m−2). Furthermore, the superhydrophilic window device was used in this work to collect the condensed water, which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water. Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment, this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.

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