Biology Inspired Superhydrophobic Surfaces

2011 ◽  
Vol 409 ◽  
pp. 814-819 ◽  
Author(s):  
J. J. Victor ◽  
D. Facchini ◽  
G. Palumbo ◽  
Uwe Erb
Keyword(s):  
Electron Microscopy ◽  
Contact Angle ◽  
Surface Structure ◽  
Tilt Angle ◽  
Elevated Temperatures ◽  
Superhydrophobic Surfaces ◽  
Optical Methods ◽  
Nanocrystalline Nickel ◽  
Structured Surface ◽  
Wetting Properties

In this study, the surface structure of a self-cleaning, superhydrophobic leaf was examined using electron microscopy and optical methods, and its wetting properties were measured using a contact angle goniometer. Using the micro/nanostructural surface features of this leaf as a blueprint, an inexpensive surface structuring technique was developed by modifying the surface of nanocrystalline nickel to create a template. These templates were then pressed into softened polyethylene at elevated temperatures and pressures, thereby transferring the structured surface to the polymer samples. All templates and pressed polymers were characterized in the same manner as the leaves. This method increased the wetting angle for polyethylene from 96° to 151° and reduced the tilt angle from 38° to <5°.

Mimicking the Nature to Achieve Superhydrophobic Surfaces by Vapor Phase Deposition

2007 ◽  
Vol 1008 ◽  
Author(s):  
Sushant Gupta ◽  
Arul Arjunan Chakkaravarthi ◽  
Rajiv Singh ◽  
Nate Stevens ◽  
Jeff Opalko ◽  
...  
Keyword(s):  
Thin Films ◽  
Contact Angle ◽  
Chemical Nature ◽  
Superhydrophobic Surfaces ◽  
Pulse Electron ◽  
Wetting Properties ◽  
Novel Technique ◽  
Ptfe Surface ◽  
Vapor Phase Deposition ◽  
Deposited Film

AbstractA novel technique was developed to create superhydrophobic polytetrafluoroethylene (PTFE) surface using nanosecond pulse electron deposition (PED) technique. The PTFE or Teflon thin films deposited on silicon substrate showed superhydrophobicity evidenced by the contact angle of 166±2 degrees. The SEM micrographs reveal the clustered growth of the deposited film and two level sub-micron asperities which is corroborated by the AFM. FTIR and contact angle studies were conducted to study the chemical nature and the wetting properties of the films.

Contact Angle Measurement in the Environmental Scanning Electron Microscope (ESEM)

2000 ◽  
Vol 6 (S2) ◽  
pp. 780-781
Author(s):  
J.P. Craven ◽  
N.A. Stelmashenko ◽  
E.M. Terentjev ◽  
B. L. Thiel
Keyword(s):  
Contact Angle ◽  
Water Vapour ◽  
High Pressures ◽  
Water Pressure ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Petroleum Engineering ◽  
Optical Methods ◽  
Depth Of Field ◽  
Wetting Properties

The ESEM uses a novel differential pumping system combined with a pressure-limiting aperture to achieve relatively high pressures of up to 10 torr in the specimen chamber. Using this system allows samples to be imaged in the presence of water vapour or other gases. Conveniently the saturated water pressure at 275K lies within this range, allowing the stabilisation of hydrated samples, condensation from water vapour and evaporation to be performed in situ within the microscope chamber.Wetting of surfaces is of fundamental importance in many different areas of science, from textiles to petroleum engineering. The ESEM now provides an opening for high-resolution studies of these phenomena without the problematic depth-of-field limitations that optical methods present. The contact angle, θ, is defined as the angle between the tangent to the liquid-fluid interface and the tangent to the solid interface. It provides a ready indication to the wetting properties of a system.

scholarly journals Surface Modification of Lightweight Mortars by Nanopolymers to Improve Their Water-Repellency and Durability

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1350 ◽  
Author(s):  
Małgorzata Szafraniec ◽  
Danuta Barnat-Hunek ◽  
Małgorzata Grzegorczyk-Frańczak ◽  
Maciej Trochonowicz
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Contact Angle ◽  
Lightweight Aggregate ◽  
Water Repellency ◽  
Fold Increase ◽  
Wetting Properties ◽  
Hydrophobic Coating ◽  
Structure Surface ◽  
Scanning Electron

The paper explores the possibility of covering the mortar with the lightweight aggregate by the nanopolymer silane and siloxane as surface hydrophobisation. The investigation involved the mortars with two types of hydrophobic agents diluted with water in a ratio of 1:4 and 1:8. Mortar wetting properties were determined by measuring the absorbability, water vapor diffusion, contact angle (CA) and surface free energy (SFE) of their structure. Surface micro-roughness and 2D topography were evaluated. Scanning electron microscopy (SEM) has shown the microstructure and distribution of pores in mortars. The reduction in absorbency after the first day of testing by 87% was shown. An improvement in frost resistance after 25 cycles by 97% and an 18-fold decrease in weight loss after the sulphate crystallization test were observed. The hydrophobic coating reduces the SFE of mortars and increases the CA. In the case of using silanes, a 9-fold increase CA was observed.

A study of the shape, surface structure and frictional wear of fibres by reflexion electron microscopy

1954 ◽  
Vol 226 (1166) ◽  
pp. 400-407 ◽  
Keyword(s):  
Electron Microscopy ◽  
Surface Structure ◽  
Friction And Wear ◽  
Permanent Deformation ◽  
Optical Microscope ◽  
Glass Wool ◽  
Optical Methods ◽  
Depth Of Field ◽  
Frictional Wear ◽  
Single Fibres

The reflexion electron microscope has been used in a direct study of the shape and surface structure of small fibres of orlon, viscose rayon, cellulose acetate, glass wool, and undrawn and drawn nylon. The images obtained are superior in resolution and depth of field to those obtained by conventional optical methods and have the particular advantage of presenting a focused image of a large part of the curved surface. It is thus possible to evaluate the shape and surface structure of a fibre much more readily than with the optical microscope. The friction and wear of single fibres of drawn nylon when a flat platinum slider is rubbed once along the fibre has been investigated, using the reflexion technique. It has been found that under high sliding pressures the fibre undergoes considerable permanent deformation and severe tearing occurs at the centre of the track.

Electrical Sheet Resistance and Wetting Properties of TiO2 Nanoparticle Thin Films Prepared by Sparking Process

2017 ◽  
Vol 866 ◽  
pp. 313-317
Author(s):  
Buppachat Toboonsung
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Contact Angle ◽  
Sheet Resistance ◽  
Water Contact Angle ◽  
Annealing Temperature ◽  
Water Contact ◽  
Titanium Dioxide Nanoparticle ◽  
Wetting Properties ◽  
Scanning Electron

An electrical sheet resistance and water contact angle of titanium dioxide nanoparticle thin films were prepared by sparking process. The experiments were carried out by the titanium wires as electrodes of sparking process and varied the sparking time of 1-4 h and the annealing temperature of 200-400 OC for 2 h. The as-deposited and as-annealed of thin films on glass substrate were measured a water contact angle and a sheet resistance whereas a surface was analyzed by a scanning electron microscopy. The results found that the optimum as-deposited TiO2 NP thin films was shown the homogeneity surface, the minimum sheet resistance and the duplicate water contact at the sparking time of 3 h. The optimum as-deposited TiO2 NP thin films was annealed which the water contact angle and the sheet resistance of the as-annealed TiO2 NP thin films decreased with increasing the annealing temperature. However, the hydrophilic property was shown optimum at the annealing temperature of 400 OC.

Superhydrophobic surfaces by dynamic nanomasking and deep reactive ion etching

2007 ◽  
Vol 221 (2) ◽  
pp. 41-48 ◽  
Author(s):  
Ying Song ◽  
Min Zou
Keyword(s):  
Contact Angle ◽  
Au Nanoparticles ◽  
Reactive Ion Etching ◽  
Thin Layers ◽  
Superhydrophobic Surfaces ◽  
Sem Images ◽  
Water Contact ◽  
Ion Etching ◽  
Deep Reactive Ion Etching ◽  
Wetting Properties

This paper reports a study on fabricating superhydrophobic surfaces with micro- and nanohierarchical topography by dynamic nanomasking (DNM) and deep reactive ion etching (DRIE). In this study, thin layers of gold (Au) were sputtered on silicon (Si) wafers followed by annealing the samples in a conventional furnace to break the thin films into Au nanoparticles attached to the Si surfaces. These randomly distributed nanoparticles served as dynamic nanomasks during DRIE processes, in which sulphur hexafluoride (SF6) and octofluorocyclobutane (C4F8) were used as etching and polymerization gases, respectively. Surface topography and wetting properties of the samples were characterized by scanning electron microscopy (SEM) and a video-based optical contact angle meter (VOCAM). SEM images show that this technique created micro-sized craters with Au nanoparticles residing on the ridges of the microstructures. The largest water contact angle (WCA) obtained by this method is about 163°. The surface superhydrophobicity is attributed to the combination of micro- and nano-hierarchical topography and surface polymerization.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

High resolution surface structure of foot-and-mouth disease virus

1978 ◽  
Vol 36 (2) ◽  
pp. 376-377
Author(s):  
S. S. Breese ◽  
H. L. Bachrach
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Surface Structure ◽  
Disease Virus ◽  
Potassium Phosphate ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Physical Measurements ◽  
Mouth Disease Virus ◽  
Foot And Mouth

Models for the structure of foot-and-mouth disease virus (FMDV) have been proposed from chemical and physical measurements (Brown, et al., 1970; Talbot and Brown, 1972; Strohmaier and Adam, 1976) and from rotational image-enhancement electron microscopy (Breese, et al., 1965). In this report we examine the surface structure of FMDV particles by high resolution electron microscopy and compare it with that of particles in which the outermost capsid protein VP3 (ca. 30, 000 daltons) has been split into smaller segments, two of which VP3a and VP3b have molecular weights of about 15, 000 daltons (Bachrach, et al., 1975).Highly purified and concentrated type A12, strain 119 FMDV (5 mg/ml) was prepared as previously described (Bachrach, et al., 1964) and stored at 4°C in 0. 2 M KC1-0. 5 M potassium phosphate buffer at pH 7. 5. For electron microscopy, 1. 0 ml samples of purified virus and trypsin-treated virus were dialyzed at 4°C against 0. 2 M NH4OAC at pH 7. 3, deposited onto carbonized formvar-coated copper screens and stained with phosphotungstic acid, pH 7. 3.

Examination of Schistosome Cercariae and Schistosomules by Scanning Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 50-51
Author(s):  
D. Johnson ◽  
P. Moriearty
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Light Microscopy ◽  
Surface Structure ◽  
Extensive Study ◽  
Scanning Microscopy ◽  
Host Parasite ◽  
Conventional Electron Microscopy ◽  
Scanning Electron

Since several species of Schistosoma, or blood fluke, parasitize man, these trematodes have been subjected to extensive study. Light microscopy and conventional electron microscopy have yielded much information about the morphology of the various stages; however, scanning electron microscopy has been little utilized for this purpose. As the figures demonstrate, scanning microscopy is particularly helpful in studying at high resolution characteristics of surface structure, which are important in determining host-parasite relationships.

Electron microscopy of crystalline structure in thermotropic random copolymers

1991 ◽  
Vol 49 ◽  
pp. 1054-1055
Author(s):  
Afzana Anwer ◽  
S. Eilidh Bedford ◽  
Richard J. Spontak ◽  
Alan H. Windle
Keyword(s):  
Electron Microscopy ◽  
Crystalline Structure ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Random Copolymers ◽  
Molecular Characteristics ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Identical Monomer ◽  
Periodic Layer

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

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