scholarly journals Facile Method to Prepare Superhydrophobic and Water Repellent Cellulosic Paper

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ioannis Karapanagiotis ◽  
Diana Grosu ◽  
Dimitra Aslanidou ◽  
Katerina E. Aifantis
Keyword(s):  
Particle Concentration ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Tissue Paper ◽  
Nanoparticle Films ◽  
High Particle ◽  
Aesthetic Appearance ◽  
Static Contact ◽  
Wide Range

Silica nanoparticles (7 nm) were dispersed in solutions of a silane/siloxane mixture. The dispersions were applied, by brush, on four types of paper: (i) modern, unprinted (blank) paper, (ii) modern paper where a text was printed using a common laser jet printer, (iii) a handmade paper sheet detached from an old book, and (iv) Japanese tissue paper. It is shown that superhydrophobicity and water repellency were achieved on the surface of the deposited films, when high particle concentrations were used (≥1% w/v), corresponding to high static (θS≈ 162°) and low tilt (θt< 3°) contact angles. To interpret these results, scanning electron microscopy (SEM) was employed to observe the surface morphologies of the siloxane-nanoparticle films. Static contact angles, measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v), increased with particle concentration and attained a maximum value (162°) which corresponds to superhydrophobicity. Increasing further the particle concentration did not have any effect onθS. Colourimetric measurements showed that the superhydrophobic films had negligible effects on the aesthetic appearance of the treated papers. Furthermore, it is shown that the superhydrophobic character of the siloxane-nanoparticle films was stable over a wide range of pH.

scholarly journals TEOS-Based Superhydrophobic Coating for the Protection of Stone-Built Cultural Heritage

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 135
Author(s):  
Fotios G. Adamopoulos ◽  
Evangelia C. Vouvoudi ◽  
Eleni Pavlidou ◽  
Dimitris S. Achilias ◽  
Ioannis Karapanagiotis
Keyword(s):  
Cultural Heritage ◽  
Water Repellency ◽  
Contact Angles ◽  
Tetraethyl Orthosilicate ◽  
Superhydrophobic Coating ◽  
Water Penetration ◽  
Wetting Properties ◽  
Aesthetic Appearance ◽  
Static Contact ◽  
Water Drops

Tetraethyl orthosilicate (TEOS) is extensively used in the conservation of stone-built cultural heritage, which is often subjected to water-induced degradation processes. The goal of this study was to produce and study a TEOS-based material with the ability to repel liquid water. A sol solution of TEOS and 1H,1H,2H,2H-perfluorooctyl triethoxysilane (FAS) was prepared and deposited on marble. The static contact angles (CAs) of water drops on the coated marble surface were >170° and the sliding angles (SA) were <5°, suggesting that superhydrophobicity and water repellency were achieved on the surface of the synthesized TEOS-based coating. FTIR and SEM-EDS were employed to characterize the produced coating. The latter offered good protection against water penetration by capillarity, reducing the breathability of marble only by a small extent and with practically no effect on its aesthetic appearance. The durability of the coating was evaluated through various tests that provided very promising results. Finally, the versatility of the method was demonstrated as the TEOS-based coating was successfully deposited onto glass, brass, wood, silicon, paper and silk, which obtained extreme wetting properties.

scholarly journals Superhydrophobic Coatings Based on Siloxane Resin and Calcium Hydroxide Nanoparticles for Marble Protection

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 334 ◽  
Author(s):  
Aikaterini Chatzigrigoriou ◽  
Ioannis Karapanagiotis ◽  
Ioannis Poulios
Keyword(s):  
Electron Microscopy ◽  
Calcium Hydroxide ◽  
Composite Coatings ◽  
Exchange Process ◽  
Sio2 Nanoparticles ◽  
Contact Angles ◽  
Water Repellent ◽  
Aqueous Emulsion ◽  
Aesthetic Appearance ◽  
Static Contact

Calcium hydroxide (Ca(OH2)) nanoparticles are produced following an easy, ion exchange process. The produced nanoparticles are characterized using transmission electron microscopy (TEM) and Fourier- transform infrared spectroscopy (FTIR) and are then dispersed in an aqueous emulsion of silanes/siloxanes. The dispersions are sprayed on marble and the surface structures of the deposited coatings are revealed using scanning electron microscopy (SEM). By adjusting the nanoparticle concentration, the coated marble obtains superhydrophobic and water repellent properties, as evidenced by the high static contact angles of water drops (> 150°) and the low sliding angles (< 10°). Because Ca(OH)2 is chemically compatible with limestone-like rocks, which are the most common stones found in buildings and objects of the cultural heritage, the produced composite coatings have the potential to be used for conservation purposes. For comparison, the wetting properties of another superhydrophobic and water repellent coating composed of the same siloxane material and silica (SiO2) nanoparticles, which were commonly used in several previously published reports, were investigated. The suggested siloxane+Ca(OH)2 composite coating offers good protection against water penetration by capillarity and has a small effect on the aesthetic appearance of marble, according to colorimetric measurements.

Development of multifunctional cotton fabric via chemical foam application method

2019 ◽  
Vol 90 (9-10) ◽  
pp. 991-1001 ◽  
Author(s):  
Zeynep Omerogullari Basyigit ◽  
Dilek Kut ◽  
Peter Hauser
Keyword(s):  
Cotton Fabric ◽  
Textile Industry ◽  
Performance Test ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Test Results ◽  
Important Place ◽  
Application Method ◽  
Color Spectrum

Nowadays, the methods and techniques used in the textile industry are required to be environmentally friendly, and water and energy saving. In addition to these, they should transfer more than one functionality, in other words give multifunctionality to the textile material with reliable and sufficient results in terms of efficiency and permanence. With the increase in and diversification of today's industrial requirements, one functionality on the fabric may be insufficient to meet the requirements, and therefore the subject of multifunctionality holds an important place in the textile industry. Therefore, in this study flame retardant, antibacterial and water-repellent, single-layered multifunctional 100% cotton fabrics with different functionalities on different sides (back and face surfaces) of the fabric were obtained via a chemical foam application method, which has many advantages compared with conventional methods. In some of the experimental parts, impregnation and foam application methods were combined in the process in order to optimize the multifunctionality properties of the fabrics. In order to indicate the performance test of cotton fabric, vertical burning test, contact angle test, antibacterial test against Gram positive and Gram negative bacteria, color spectrum analysis and tearing strength test were carried out while, in terms of characterization tests, Fourier transform infrared (attenuated total reflectance) and scanning electron microscope analyses were performed. According to the test results, the flame retardancy effect of the samples was improved significantly while antibacterial results showed a 99% reduction of bacteria and the finished fabrics demonstrated improved water repellency with contact angles up to 125°. In addition, the functionalities were durable up to 50 washing and 50 drying cycles.

scholarly journals Fluorosilane Water-Repellent Coating for the Protection of Marble, Wood and Other Materials

Heritage ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 2668-2675
Author(s):  
Fotios G. Adamopoulos ◽  
Evangelia C. Vouvoudi ◽  
Dimitris S. Achilias ◽  
Ioannis Karapanagiotis
Keyword(s):  
Polymer Networks ◽  
Treated Wood ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Capillary Absorption ◽  
Durability Test ◽  
Water Contact ◽  
Produce Water ◽  
The Aesthetic

The preservation of cultural heritage monuments and artifacts requires the development of methods to produce water-repellent materials, which can offer protection against the effects of atmospheric water. Fluorosilanes are a very promising class of materials, as they act as precursors for the formation of low surface energy polymer networks. 1H,1H,2H,2H-perfluorooctyl-triethoxysilane is applied on marble, wood and the surfaces of other materials, such as glass, silicon wafer, brass, paper and silk. According to the measurements of static water contact angles, it is reported that superhydrophobicity and enhanced hydrophobicity are achieved on the surfaces of coated marble and wood, respectively. Hydrophobicity and hydrophilicity were observed on the treated surfaces of the other materials. More important, water repellency is achieved on any hydrophobic or superhydrophobic surface, as revealed by the very low sliding angles of water drops. The study is accompanied by colorimetric measurements to evaluate the effects of the treatment on the aesthetic appearances of the investigated materials. Finally, the capillary absorption test and a durability test are applied on treated wood and marble, respectively. 

scholarly journals Air retaining grids—a novel technology to maintain stable air layers under water for drag reduction

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190126 ◽  
Author(s):  
M. Mail ◽  
M. Moosmann ◽  
P. Häger ◽  
W. Barthlott
Keyword(s):  
Drag Reduction ◽  
Stable Solution ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Lotus Effect ◽  
Ship Hulls ◽  
First Results ◽  
Air Layers ◽  
Micro Pillars

Extreme water repellent ‘superhydrophobic’ surfaces evolved in plants and animals about 450 Ma: a combination of hydrophobic chemistry and hierarchical structuring causes contact angles of greater than 150°. Technical biomimetic applications and technologies for water repellency, self-cleaning (Lotus Effect) and drag reduction (Salvinia Effect) have become increasingly important in the last two decades. Drag reduction (e.g. for ship hulls) requires the presence of a rather thick and persistent air layer under water. All existing technical solutions are based on fragile elastic hairs, micro-pillars or other solitary structures, preferably with undercuts (Salvinia Effect). We propose and provide experimental data for a novel alternative technology to trap persistent air layers by superhydrophobic grids or meshes superimposed to the solid surface: AirGrids. AirGrids provide a simple and stable solution to generate air trapping surfaces for drag reduction under water as demonstrated by first prototypes. Different architectural solutions, including possible recovery techniques for the air layer under hydrodynamic conditions, are discussed. The most promising target backed by first results is the combination of Air Retaining Grids with the existing microbubble technology. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Natural colloid mobilization and leaching in wettable and water repellent soil under saturated condition

2018 ◽  
Vol 66 (3) ◽  
pp. 271-278 ◽  
Author(s):  
Nasrollah Sepehrnia ◽  
Olga Fishkis ◽  
Bernd Huwe ◽  
Jörg Bachmann
Keyword(s):  
Organic Matter ◽  
Colloidal Particles ◽  
Sessile Drop ◽  
Organic Matter Content ◽  
Water Repellency ◽  
Contact Angles ◽  
Matter Content ◽  
Soil Horizon ◽  
Water Repellent ◽  
Coupled Transport

AbstractThe coupled transport of pollutants that are adsorbed to colloidal particles has always been a major topic for environmental sciences due to many unfavorable effects on soils and groundwater. This laboratory column study was conducted under saturated moisture conditions to compare the hydrophobic character of the suspended and mobilized colloids in the percolates released from a wettable subsoil and a water repellent topsoil. Both soils with different organic matter content were analyzed for wettability changes before and after leaching using sessile drop contact angles as well as water and ethanol sorptivity curves, summarized as repellency index. Hydrophobicity of the effluent suspensions was assessed using the C18 adsorption method. Water repellency level of the repellent soil decreased after leaching but remained on a lower level of water repellency, while, the wettable soil remained wettable. The leached colloids from the repellent soil were predominantly hydrophilic and the percentage of the hydrophobic colloid fraction in the effluent did not systematically changed with time. Total colloid release depended on soil carbon stock but not on soil wettability. Our results suggest that due to the respective character of transported colloids a similar co-transport mechanism for pollutants may occur which does not depend explicitly on soil wettability of the releasing horizon, but could be more affected by total SOM content. Further studies with a wider range of soils are necessary to determine if the dominant hydrophilic character of leached colloids is typical. Due to the mostly hydrophilic colloid character we conclude also that changes in wettability status, i.e. of wettable subsoil horizons due to the leachate, may not necessarily occur very fast, even when the overlaying topsoil is a repellent soil horizon with a high organic matter content.

Extreme hydrophobicity and omniphilicity of high-aspect-ratio silicon structures

2015 ◽  
Vol 29 (06n07) ◽  
pp. 1540009 ◽  
Author(s):  
Moon Kyu Kwak ◽  
Cheol Woo Park ◽  
Kwang-Il Hwang ◽  
Choon Man Park ◽  
Hoon Eui Jeong ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Environmental Remediation ◽  
Water Repellency ◽  
Contact Angles ◽  
Experimental Simulation ◽  
Black Silicon ◽  
Water Separation ◽  
Static Contact ◽  
Silicon Structures

We present an application of high-aspect-ratio (high-AR) silicon structures (black silicon) with high water repellency and good wettability by oils and solvents. The fabrication of black silicon consists of a deep reactive-ion etching process for extremely-high-AR silicon structures and surface treatment with C 4 F 8 gas. Such high-AR structures were found to be highly resistant against wetting by water, but they also have good wetting characteristics with respect to certain liquids such as ethanol, hexane and mineral oil. To determine the relationship between the AR of nanostructures and wetting selectivity, four different black silicon samples with different pattern heights were used. The static contact angles of various liquid were measured for the analysis of wetting properties of the four black silicon samples. To explore feasible applications, ethanol–water separation was performed as a miniaturized experimental simulation of environmental remediation.

Superhydrophobic and transparent surfaces on cotton fabrics coated with silica nanoparticles for hierarchical roughness

2016 ◽  
Vol 87 (5) ◽  
pp. 552-560 ◽  
Author(s):  
Seon Ah Jeong ◽  
Tae Jin Kang
Keyword(s):  
Silica Nanoparticles ◽  
Contact Angle Hysteresis ◽  
Water Repellency ◽  
Cotton Fabrics ◽  
Contact Angles ◽  
Water Repellent ◽  
Textile Fabrics ◽  
Hierarchical Roughness ◽  
Silica Nanomaterials ◽  
Alcohol Solvent

Superhydrophobic and transparent surfaces on cotton fabrics have been developed using silica nanomaterials. Initially, trichlorododecylsilane was treated on the silica nanoparticles to lower the surface energy of the fabric. By simply spraying alcohol suspensions containing hydrophobized silica nanoparticles, extremely water repellent coatings were formed on the textile fabrics. The effect of three types of alcohol solvent on the hydrophobicity of the coated cotton fabrics was examined by measuring the surface wettability. The treated cotton textiles in methanol exhibited contact angles higher than 160°, contact angle hysteresis lower than 10°, and good water repellency. It proved to be essential to form hierarchical morphology in achieving superhydrophobicity.

The isolation and characterisation of bacteria with the potential to degrade waxes that cause water repellency in sandy soils

Soil Research ◽  
2004 ◽  
Vol 42 (4) ◽  
pp. 427 ◽  
Author(s):  
Margaret M. Roper
Keyword(s):  
Agricultural Production ◽  
Complex Mixture ◽  
Sandy Soils ◽  
Water Repellency ◽  
Water Repellent ◽  
Bacterial Isolates ◽  
Hydrophobic Compounds ◽  
Degrading Bacteria ◽  
Wide Range ◽  
Fatty Acids And Alcohols

Water repellency in soils is caused by waxy coatings on particles and can seriously limit agricultural production. Bioremediation of these soils, using wax-degrading bacteria isolated from soils and other sources rich in microorganisms, was investigated. Wool wax, a complex mixture of fatty acids and alcohols, was used to select bacteria capable of metabolising hydrophobic compounds. Of the 37 stable isolates, two-thirds were actinomycetes. These organisms are known for their ability to metabolise a wide range of organic compounds. Degradation of waxes associated with soil particles is facilitated by the production of biosurfactants that emulsify hydrophobic compounds. Measurement of biosurfactant production indicated that those isolates that grew best on hydrocarbon were also the most prolific biosurfactant producers. Inoculation of water-repellent soils, under controlled conditions, with the most efficient wax-degrading bacterial isolates resulted in significant improvements in soil wettability.

scholarly journals Influence of organic manure amendments on water repellency, water entry value, and water retention of soil samples from a tropical Ultisol

2016 ◽  
Vol 64 (2) ◽  
pp. 160-166 ◽  
Author(s):  
T.D.P. Liyanage ◽  
D.A.L. Leelamanie
Keyword(s):  
Organic Matter ◽  
Soil Water ◽  
Water Retention ◽  
Water Repellency ◽  
Water Entry ◽  
Contact Angles ◽  
Organic Manure ◽  
Water Repellent ◽  
Water Contact ◽  
In Series

AbstractLowered stability of soil aggregates governed by insufficient organic matter levels has become a major concern in Sri Lanka. Although the use of organic manure with water repellent properties lowers the wetting rates and improves the stability of soil aggregates, its effects on soil hydrophysical properties are still not characterized. Therefore, the objective of this study was to examine the relation of water repellency induced by organic manure amendments to the water entry value and water retention of a Sri Lankan Ultisol. The soil was mixed with ground powders of cattle manure (CM), goat manure (GM),Gliricidia maculata(GL) and hydrophobicCasuarina equisetifolia(CE) leaves to obtain samples ranging from non-repellent to extremely water repellent, in two series. Series I was prepared by mixing GL and CE with soil (5, 10, 25, 50%). Series II consisted of 5% CM, GM, and GL, with (set A) and without (set B) intermixed 2% CE. Water repellency, water entry value, and water retention of samples were determined in the laboratory. Soil-water contact angle increased with increasing organic matter content in all the samples showing positive linear correlations. Although the samples amended with CE showed high soil-water contact angles in series I, set A (without 2% CE) and set B (with 2% CE) in series II did not show a noticeable difference, where >80% of the samples had soil-water contact angles <90°. Water entry value (R2= 0.83–0.92) and the water retention at 150 cm suction (R2= 0.69–0.8) of all the samples increased with increasing soil-water contact angles showing moderate to strong positive linear correlations. However, set A (without 2% CE) and set B (with 2% CE) in series II did not differ noticeably. Water entry value of about 60% the samples was <2.5 cm. Mixing of a small amount (2%) of hydrophobic organic matter with commonly used organic manures slightly increased the water repellency of sample soils, however not up to detrimental levels. It did not generate adverse effects on water entry and increased the water retention. It was clear that intermixing of small quantities of hydrophobic organic manure with organic manures commonly used in Sri Lankan agriculture, would not generate unfavorable impacts on soils.

Sign in / Sign up

Export Citation Format

Share Document