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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.

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