Condensate Microdrop Self-propelling Research Articles

Fabrication and Condensate Microdrop Self-Propelling of Biomimetic Nanostructured Polymer Surfaces without Chemical Modification

Condensate microdrop self-propelling (CMDSP) can occur on the cicada wing surfaces due to very low solid–liquid adhesion of the closely packed nanopillars. A promising and industrial strategy is proposed for successively replicating the nanopillars on the cicada wing onto the polypropylene (PP) surfaces. Its process includes nickel replica fabrication and PP replica injection molding. Packed nanopillars with nanoscale interspaces endow the PP replicas with CMDSP functionality. Mechanism for the CMDSP on the PP replica is analyzed. This work should be the first report of achieving the CMDSP function on polymer surfaces without chemical modification, which is favorable for industrial applications such as anti-icing/frosting and enhanced condensation heat transfer.

Bio‐Inspired Superhydrophobic Closely Packed Aligned Nanoneedle Architectures for Enhancing Condensation Heat Transfer

AbstractBionic condensate microdrop self‐propelling (CMDSP) surfaces are attracting intensive interest due to their academic and commercial values. Up to now, it is still a great challenge to design and fabricate CMDSP nanostructures with superior condensation heat transfer (CHT) efficiency. Here, it is reported that the CHT coefficient of copper surfaces can be enhanced maximally ≈320% via in situ growth and geometric regulation of closely packed aligned nanoneedles with CMDSP function. These experiments and theoretical analyses indicate that reducing the interspaces of nanoneedles can help reduce the departure diameters of condensate microdrops and increase their nucleation density, both of which are beneficial to enhance CHT. In contrast, increasing the tip size and height of nanoneedles can increase drop departure diameters and film‐layer thermal resistance, respectively, either of which is disadvantageous to enhance CHT. Clearly, only considering superhydrophobic effect is insufficient and both choosing ideal nanoarchitectures and optimizing their geometric parameters are very crucial to realize high‐efficiency CHT, which optimization can be achieved via simply controlling growth time of nanostructures. These findings offer new insights into the design and development of first‐rank CHT interface nanomaterials.

Recent Progress in Bionic Condensate Microdrop Self-Propelling Surfaces.

Bionic condensate microdrop self-propelling (CMDSP) surfaces are attracting increased attention as novel, low-adhesivity superhydrophobic surfaces due to their value in fundamental research and technological innovation, e.g., for enhancing heat transfer, energy-effective antifreezing, and electrostatic energy harvesting. Here, the focus is on recent progress in bionic CMDSP surfaces. Metal-based CMDSP surfaces, which are the most promising in their respective fields, are highlighted for use in future applications. The selected topics are divided into four sections: biological prototypes, mechanism and construction rules, fabrication, and applications of metal-based CMDSP surfaces. Finally, the challenges and future development trends in bionic CMDSP surfaces are envisioned, especially the utilization of potential bionic inspiration in the design of more advanced CMDSP surfaces.

Design and Fabrication of a Tip‐Like ZnO Nanotube Array Structure with Condensate Microdrop Self‐Propelling Function

AbstractHere, we present a type of tip‐like nanotube array with condensate microdrop self‐propelling (CMDSP) function. Based on the basic principle that condensate microdrops can self‐remove via coalescence‐released weak surface energy as long as interface adhesion induced energy dissipation is sufficiently low, we design tip‐like nanotubes with extremely low solid–liquid interface adhesion. To verify the feasibility of this idea, we propose a strategy of preferential etching of six corners and the interior of ZnO nanopencils to achieve tip‐like nanotubes. Our studies demonstrate that this nanostructure can be achieved by immersing ZnO nanopencils in 0.006 m HCl aqueous solution at 80 °C for 3 h. After silane modification, the resulting nanostructure shows CMDSP function. This work offers a new avenue for developing CMDSP functional films, which can find a variety of technological applications such as moisture self‐cleaning, antifrosting and enhancing heat transfer.

Understanding the Role of Dynamic Wettability for Condensate Microdrop Self-Propelling Based on Designed Superhydrophobic TiO2 Nanostructures.

The ability to release the adhered drops on superhydrophobic surfaces is very important for self-cleaning, antifrosting/icing, microfluidic device, and heat transfer applications. In this paper, three types of in situ electrochemical anodizing TiO2 nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO2 nanotube arrays, irregular TiO2 nanotube arrays, and hierarchical TiO2 particle arrays (HTPA), and their corresponding behavior in condensate microdrop self-propelling (CMDSP) is investigated. Compared to the flat titanium counterpart, all three types of rough TiO2 samples demonstrate a uniform distribution of smaller microscale droplets. Among the treated surfaces, the HTPA possesses the highest condensate density, and more than 80% of the droplets possess a diameter below 10 μm. Theoretical analysis indicates that the feature is mainly due to the morphology and structure induced extremely low droplet adhesion on super-antiwetting TiO2 hierarchical surfaces, where the excess surface energy released from the migration leads to the self-propelling of merged microdrop. This work offers a way to rationally construct CMDSP surfaces with excellent self-cleaning, antifrosting/icing ability, and enhanced condensation heat transfer efficiency.

Design and fabrication of clustered rugged ZnO nanotube films with condensate microdrop self-propelling function.

We design and fabricate a type of condensate microdrop self-propelling (CMDSP) clustered rugged nanotube film, which is achieved by two-step electrodeposition and low-surface-energy silane modification. This work offers an avenue for developing CMDSP surfaces with self-cleaning, antifrosting, and antidewing functions.

Facile Fabrication of Anodic Alumina Rod-Capped Nanopore Films with Condensate Microdrop Self-Propelling Function.

We report that aluminum surfaces can be endowed with condensate microdrop self-propelling (CMDSP) function by one-step voltage-rising mild anodization in hot phosphoric acid solution followed by fluorosilane modification. Via regulating reaction parameters, we can achieve anodic alumina self-standing rod-capped nanopore films and minimize their solid-liquid interface adhesion. Such low-adhesive nanostructured film owns remarkable CMDSP function, especially to condensate microdrops with sizes below 50 μm, differing from usual gravity-driven dropwise condensation on flat aluminum surfaces. Clearly, this work offers a facile, efficient, and industry-compatible approach to processing CMDSP aluminum materials, which is significant for developing innovative energy-saving air-conditioner heat exchangers.

Copper-Based Ultrathin Nickel Nanocone Films with High-Efficiency Dropwise Condensation Heat Transfer Performance.

We report a type of copper-based ultrathin nickel nanocone films with high-efficiency dropwise condensation heat transfer (DCHT) performance, which can be fabricated by facile electrodeposition and low-surface-energy chemistry modification. Compared with flat copper samples, our nanosamples show condensate microdrop self-propelling (CMDSP) function and over 89% enhancement in the DCHT coefficient. Such remarkable enhancement may be ascribed to the cooperation of surface nanostructure-induced CMDSP function as well as in situ integration and ultrathin nature of nanofilms. These findings are very significant to design and develop advanced DCHT materials and devices, which help improve the efficiency of thermal management and energy utilization.

Condensate Microdrop Self-Propelling Aluminum Surfaces Based on Controllable Fabrication of Alumina Rod-Capped Nanopores

Here, we report a type of aluminum-based condensate microdrop self-propelling (CMDSP) functional films based on the controllable fabrication of anodic alumina rod-capped nanopores, which can be realized by a three-step method based on the skillful combinations of well-established hard anodization, mild anodization and chemical etching techniques. Such a surface nanoengineering strategy is verified to be feasible via our exemplified experiments and scanning electronic microscopy characterizations. After fluorosilane modification, the surface nanostructure can induce the efficient self-jumping of small-scale condensate microdrops, especially below 50 μm. This work offers an avenue for developing CMDSP aluminum surfaces with self-cleaning, antifrosting, and antidewing functions.

Fabrication of condensate microdrop self-propelling porous films of cerium oxide nanoparticles on copper surfaces.

Condensate microdrop self-propelling (CMDSP) surfaces have attracted intensive interest. However, it is still challenging to form metal-based CMDSP surfaces. We design and fabricate a type of copper-based CMDSP porous nanoparticle film. An electrodeposition method based on control over the preferential crystal growth of isotropic nanoparticles and synergistic utilization of tiny hydrogen bubbles as pore-making templates is adopted for the in situ growth of cerium oxide porous nanoparticle films on copper surfaces. After characterizing their microscopic morphology, crystal structure and surface chemistry, we explore their CMDSP properties. The nanostructure can realize the efficient ejection of condensate microdrops with sizes below 50 μm.

Fabrication of Condensate Microdrop Self‐Propelling Porous Films of Cerium Oxide Nanoparticles on Copper Surfaces

AbstractCondensate microdrop self‐propelling (CMDSP) surfaces have attracted intensive interest. However, it is still challenging to form metal‐based CMDSP surfaces. We design and fabricate a type of copper‐based CMDSP porous nanoparticle film. An electrodeposition method based on control over the preferential crystal growth of isotropic nanoparticles and synergistic utilization of tiny hydrogen bubbles as pore‐making templates is adopted for the in situ growth of cerium oxide porous nanoparticle films on copper surfaces. After characterizing their microscopic morphology, crystal structure and surface chemistry, we explore their CMDSP properties. The nanostructure can realize the efficient ejection of condensate microdrops with sizes below 50 μm.