Showing papers by "Wenli Deng published in 2014"

Chemically Stable and Mechanically Durable Superamphiphobic Aluminum Surface with a Micro/Nanoscale Binary Structure

Abstract: We developed a simple fabrication method to prepare a superamphiphobic aluminum surface. On the basis of a low-energy surface and the combination of micro- and nanoscale roughness, the resultant surface became super-repellent toward a wide range of liquids with surface tensions of 25.3–72.1 mN m–1. The applied approach involved (1) the formation of an irregular microplateau structure on an aluminum surface, (2) the fabrication of a nanoplatelet structure, and (3) fluorination treatment. The chemical stability and mechanical durability of the superamphiphobic surface were evaluated in detail. The results demonstrated that the surface presented an excellent chemical stability toward cool corrosive liquids (HCl/NaOH solutions, 25 °C) and 98% concentrated sulfuric acid, hot liquids (water, HCl/NaOH solutions, 30–100 °C), solvent immersion, high temperature, and a long-term period. More importantly, the surface also exhibited robust mechanical durability and could withstand multiple-fold, finger-touch, intensi...

Highly Efficient and Large-Scale Fabrication of Superhydrophobic Alumina Surface with Strong Stability Based on Self-Congregated Alumina Nanowires

Abstract: In this study, a large-area superhydrophobic alumina surface with a series of superior properties was fabricated via an economical, simple, and highly effective one-step anodization process, and subsequently modified with low-surface-energy film. The effects of the anodization parameters including electrochemical anodization time, current density, and electrolyte temperature on surface morphology and surface wettability were investigated in detail. The hierarchical alumina pyramids-on-pores (HAPOP) rough structure which was produced quickly through the one-step anodization process together with a low-surface-energy film deposition [1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES) and stearic acid (STA)] confer excellent superhydrophobicity and an extremely low sliding angle. Both the PDES-modified superhydrophobic (PDES-MS) and the STA-modified superhydrophobic (STA-MS) surfaces present fascinating nonwetting and extremely slippery behaviors. The chemical stability and mechanical durability of the PDES-MS...

Steric matching and the concentration induced self-assembled structural variety of 2,7-bis(n-alkoxy)-9-fluorenone at the aliphatic solvent/graphite interface

Abstract: Controlling and unraveling structural polymorphism has received special attention in 2D self-assembled monolayers. In this work, we investigated the steric matching and solution concentration controlled structural variety in the self-assembly of 2,7-bis(n-alkoxy)-9-fluorenone (F–OCn) at the n-tetradecane and n-tridecane/graphite interface under different concentrations, respectively. Scanning tunneling microscopy (STM) revealed that the coadsorbed adlayers of F–OCn and solvents (n = 12 to 16) were formed and exhibited concentration dependent 2D phases due to the steric matching. The self-assembled monolayer of F–OCn (n = 12 to 16) evolved from a low-density coadsorbed linear lamellar packing, which was formed at low concentrations, to higher-density patterns at relatively high concentrations. F–OC14 exhibited a complex structural variety, in which a systematic trend of decrease in the molecular density per unit cell with decreasing concentration was obtained. Except for F–OCn (n = 13, 15, 17), the zigzag structure showing the linear lamella with dimers was observed. Systematic experiments revealed that the self-assembly of F–OCn was chain-length dependent. The results provide insight into the structural variety exhibited by a series of organic molecules and furnish important guidelines to control the morphology by changing the solution concentration.

A facile approach for preparing biomimetic polymer macroporous structures with petal or lotus effects

Abstract: In this paper, three kinds of superhydrophobic polymethylmethacrylate (PMMA) macroporous membranes with controlled adhesion were fabricated by a simple hierarchical alumina template wetting method. This alumina template was obtained through a convenient one-step anodization method, achieving a hierarchical structure combining the upper macroporous structure and lower nanopore topography. These final PMMA products perfectly replicate the original macroporous structure of the template. By simply controlling the reaction temperature, we can obtain the different PMMA surfaces with diverse topographies. The testing results confirm that the PMMA samples not only could achieve superhydrophobicity after the post-modification treatment but also present huge differences in adhesive abilities. The shallow bowl-shape structure presents a slippery property, which has a low sliding angle (SA) of 3°; the deep bowl-shape morphology possesses a SA of 30°, presenting a little sticky performance; the deep honey-comb texture possesses a large SA, which can hold a 10 μL water droplet even upside down, totally showing strong sticky water adhesion. Noticeably, the as-prepared superhydrophobic PMMA samples have remarkable resistivity to acid/alkali, various organic solvents and a long-time period. Moreover, the approach in this work can also be applied to any other soluble polymers. It is believed that our work provide a convenient and promising method to prepare polymer superhydrophobic surfaces with controlled adhesion, which has been rarely reported up to now.

Two-dimensional self-assembly of single-, poly- and co-crystals at the liquid/solid interface

Abstract: Studying two-dimensional (2D) and three-dimensional (3D) crystallization in tandem is a powerful way to acquire a deep understanding of molecular self-assembly. X-ray crystallography results indicate that N-[6-(fluoren-9-ylideneamino)hexyl]fluoren-9-imine (C1), N-[12-(fluoren-9-ylideneamino)dodecyl]fluoren-9-imine (C2), and co-crystal of naphthalene-1,5-diamine and 9-fluorenone (C3) are single-, poly- and co-crystals, respectively. Furthermore, the self-assembled structures of these three kinds of crystals (C1, C2 and C3) at the 1-phenyloctane/HOPG interface are investigated using scanning tunneling microscopy under ambient conditions. The C1 molecule, with a short chain, is lying flat on the substrate with a close packing phase, which is the same in its 3D crystal structure. The C2 molecule, bearing a longer chain, forms two types of linear structures, which are stable enough to endure continuous tip scanning. In Type I, the C2 molecules lie flat on the substrate to form a linear zigzag pattern, while in Type II one of the fluorene cores in each C2 molecule adopts an edge-on arrangement and interlocks with the adjacent fluorene core in one lamella. In the co-crystal C3, naphthalene-1,5-diamine and 9-fluorenone arrange perpendicular to the HOPG surface in a herringbone pattern via hydrogen bonds and π–π interactions. The lying or standing orientation of the three kinds of crystals show that the functional groups tethered to the middle spacer can modulate the motifs of self-assembly in the 2D and 3D crystallization. Furthermore, it also highlights that physical adsorption on the HOPG surface is not only controlled by the adsorbate–substrate interactions but also by the size and shape of the adsorbates.