Recently, superhydrophobic surfaces with tunable wettability have aroused much attention. Noticeably, almost all present smart performances rely on the variation of surface chemistry on static micro/nanostructure, to obtain a surface with dynamically tunable micro/nanostructure, especially that can memorize and keep different micro/nanostructures and related wettabilities, is still a challenge. Herein, by creating micro/nanostructured arrays on shape memory polymer, a superhydrophobic surface that has shape memory ability in changing and recovering its hierarchical structures and related wettabilities was reported. Meanwhile, the surface was successfully used in the rewritable functional chip for droplet storage by designing microstructure-dependent patterns, which breaks through current research that structure patterns cannot be reprogrammed. This article advances a superhydrophobic surface with shape memory hierarchical structure and the application in rewritable functional chip, which could start some fresh ideas for the development of smart superhydrophobic surface.
Smart surfaces with tunable wettability have aroused much attention in the past few years. However, to obtain a surface that can reversibly transit between the lotus-leaf-like superhydrophobic isotropic and rice-leaf-like superhydrophobic anisotropic wettings is still a challenge. This paper, by mimicking microstructures on both lotus and rice leaves, reports such a surface that is prepared by creating micro/nanostructured arrays on the shape memory polymer. On the surface, the microstructure shapes can be reversibly changed between the lotus-leaf-like random state and the rice-leaf-like 1D ordered state. Accordingly, repeated switch between the superhydrophobic isotropic and anisotropic wettings can be displayed. Research results indicate that the smart controllability is ascribed to the excellent shape memory effect of the polymer, which endows the surface with special ability in memorizing different microstructure shapes and wetting properties. Meanwhile, based on the smart wetting performances, the surface is further used as a rewritable functional platform, on which various droplet transportation programmes are designed and demonstrated. This work reports a superhydrophobic surface with switchable isotropic/anisotropic wettings, which not only provides a novel functional material but also opens a new avenue for application in controlled droplet transportation.
Metal–organic
framework (MOF)-derived magnetic metal/carbon
nanocomposites have shown tremendous potential for lightweight electromagnetic
wave (EMW) absorption. However, it is a challenge but highly significant
to design and construct mixed-dimensional hierarchical architectures
with synergistically integrated characteristics from individual MOFs
for advancing the EMW absorption performance. Inspired by the structure
of cactus, a novel hierarchical one-dimensional (1D)–two-dimensional
(2D) mixed-dimensional Co/N-decorated carbon architecture comprising
carbon nanotubes grafted on carbon flakes (abbreviated as CoNC/CNTs)
has been fabricated by the pyrolysis of bimetallic CoZn-ZIF-L. The
CoNC/CNTs integrate the advantages of 1D nanotubes for the extra polarization
of EMW and 2D nanoflakes with an interconnected porous structure for
multiple reflection losses of EMW and optimization of impedance matching.
The resultant CoNC/CNTs demonstrate excellent EMW absorbing performance.
For the optimal EMW absorbing material of CoNC/CNT-3/1, minimum reflection
loss reaches −44.6 dB at 5.20 GHz with a low filler loading
of 15 wt %. Moreover, the largest effective bandwidth range achieves
4.5 GHz with a thickness of 1.5 mm and a filled ratio of 20 wt %.
These findings indicate that such a mixed 1D–2D hierarchical
architecture synergistically enhances EMW absorbing performance. This
work sheds light on the rational design of a mixed-dimensional carbon
architecture derived from MOFs for desirable functionalities.
Recently, self-healing superhydrophobic surfaces have become a new research focus due to their recoverable wetting performances and wide applications. However, until now, on almost all reported surfaces, only one factor (surface chemistry or microstructure) can be restored. In this paper, a new superhydrophobic surface with self-healing ability in both crushed microstructure and damaged surface chemistry is prepared by creating lotus-leaves-like microstructure on the epoxy shape memory polymer (SMP). Through a simple heating process, the crushed surface microstructure, the damaged surface chemistry, and the surface superhydrophobicity that are destroyed under the external pressure and/or O plasma action can be recovered, demonstrating that the obtained superhydrophobic surface has a good self-healing ability in both of the two factors that govern the surface wettability. The special self-healing ability is ascribed to the good shape memory effect of the polymer and the reorganization effect of surface molecules. This paper reports the first use of SMP material to demonstrate the self-healing ability of surface superhydrophobicity, which opens up some new perspectives in designing self-healing superhydrophobic surfaces. Given the properties of this surface, it could be used in many applications, such as self-cleaning coatings, microfluidic devices, and biodetection.
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