hydrophobic materials examples

• Hydrophobic materials in biology are substances that do not dissolve in water, repel water, or are themselves repelled by water molecules.
• Examples include greases, waxes, steroids, alkanes, and fats. Hydrophobic materials exhibit characteristics of nonpolarity, formation of micelles, and an affinity to bond to other nonpolar substances.
• Hydrophobic substances are useful in molecular folding, nanotechnology, biomedicine, and gains in energy efficiency.

What are examples of hydrophobic substances?

Examples of hydrophobic substances include fats, oils, waxes, alkanes and other greasy substances. The term hydrophobic comes from the Greek and is translated as “having a horror of water” or “water fearing.”. In other words, hydrophobicity is a property of a substance that repels water. This means lacking affinity for water, tending ...

What compounds are hydrophobic?

Oils, fats, alkanes, and most other organic compounds are hydrophobic. If you mix oil or fat with water, the mixture will separate. If you shake a mixture of oil and water, the oil globules will eventually stick together to present a minimum surface area to the water. Hydrophobic molecules are nonpolar.

What makes something hydrophobic?

what makes fats hydrophobic

• Fats – biochemistry
• Hydrophilic vs Hydrophobic | Substances | Cell Membranes. What is fat?
• Unsaturated vs Saturated vs Trans Fats, Animation

What are some examples of hydrophilic substances?

There are many hydrophilic molecules examples, such as:

• Glucose (sugar)
• Starch
• Cellulose
• Amino acids (some)
• Ethanol
• Methanol
• Sodium chloride
• Sodium hydroxide

What are hydrophobic materials?

Hydrophobic materials are known as non-polar materials with a low affinity to water, which makes them water repelling. A contact angle of less than 90° indicates hydrophilic interaction where as an angle greater than 90° indicates a hydrophobic interaction.

What is an example of a hydrophilic material?

Examples of hydrophilic liquids include ammonia, alcohols, some amides such as urea and some carboxylic acids such as acetic acid.

What materials are naturally hydrophobic?

Natural hydrophobes include alkanes, fats and oils. Hydrophobic materials are often used to remove oil from water, manage oil spills, and chemical separation processes that require the removal of non-polar substances from polar compounds.

Which are example is hydrophobic in nature?

Alkanes, oils, fats, and greasy compounds are hydrophobic in nature. The process of hydrophobicity can be found in both plants and birds.

What is hydrophobic and hydrophilic examples?

Many metal surfaces are hydrophilic, for example aluminium foil. Hydrophobic surfaces tend to repel water, causing it to form droplets; lotus leaves are incredibly hydrophobic and cause water to bead, due to their surface structure.

Is soap hydrophobic or hydrophilic?

Soap is made of pin-shaped molecules, each of which has a hydrophilic head — it readily bonds with water — and a hydrophobic tail, which shuns water and prefers to link up with oils and fats.

Is paper a hydrophobic material?

However, the hydrophilic nature of paper due to the presence of -OH groups limits its application in various sectors. Paper can absorb water from the environment or from food and become hydrated (Khwaldia 2010).

Is plastic hydrophobic?

During healthcare and pharmaceutical product development, hydrophilicity is a crucial factor in determining the product performance limits, and a challenge that porous plastic manufacturers face is that plastic polymers are naturally hydrophobic; that is, liquids bead up on the surface and do not form strong ...

Is wax a hydrophobic material?

Plant-derived wax has excellent hydrophobicity because its main components are esters of long-chain fatty alcohols, acids, and long-chain alkanes (Saji 2020) . Therefore, such wax is a natural medium for the preparation of hydrophobic materials. ...

Are metals hydrophobic?

The negative solvation free energy implies that whereas the bare metal surface attracts water, the composite water–metal surface is hydrophobic and as such preferentially attracts oil.

Is olive oil hydrophobic?

Olive oil is hydrophobic. It doesn't mix with water and presents the minimum surface area to water.

Is wood hydrophilic?

Wood is porous and hydrophilic, and transformation of the surface from hydrophilic to hydrophobic is often associated with blockage, modification, or removal of hydroxyls present in cellulose, hemicelluloses, and lignin.

What are some examples of hydrophobic substances?

Examples of hydrophobic substances include fats, oils, waxes, alkanes and other greasy substances. The term hydrophobic comes from the Greek and is translated as “having a horror of water” or “water fearing.”. In other words, hydrophobicity is a property of a substance that repels water.

Why are hydrophobic materials used in oil spills?

This is because they are waterproof, corrosion resistant and stable against inorganic and organic pollutants.

Why is hydrophobic effect important?

When this happens, the hyrophobes have less contact with water. The hydrophobic effect is important for biological structures and is responsible for protein folding, protein-to- protein interactions and the formation of nucleic acid structures and lipid-bilayer membranes. ADVERTISEMENT.

Does water repel hydrophobes?

Unlike water, hydrophobes cannot form hydrogen bonds; therefore, water tends to repel hydrophobes; instead, preferring to bond with itself. This is referred to as the hydrophobic effect or hydrophobic interaction.

Can hydrophobic substances dissolve in water?

Hydrophobic substances cannot dissolve in water as their molecules tend to be nonpolar. These molecules are known as hydrophobes or water-insoluble molecules, and they tend to attract nonpolar solvents and neutral molecules. Unlike water, hydrophobes cannot form hydrogen bonds; therefore, water tends to repel hydrophobes; instead, ...

What are hydrophobic materials?

Natural hydrophobes include alkanes, fats and oils. Hydrophobic materials are often used to remove oil from water, manage oil spills, and chemical separation processes that require the removal of non-polar substances from polar compounds. Ross Nanotechnology's NeverWet superhydrophobic spray-on coating.

How to make glass hydrophobic?

Material scientists have been working on using various chemicals to alter the surface properties of a surfaces to make them hydrophobic. To provide glass with a hydrophobic characteristic, silanes are often used. The leaves of lotus have been a great source of inspiration in the formation of superhydrophobic materials. Studies revealed that the rough surface of the leaves contain wax nanocrystals, which aids the repulsion of water. The water drops come in contact with a large fraction of air that forces it to form a bead shape and slide off the surface. Another extremely useful benefit of this is that as the water slides off, it also drags the surface dirt with it, rendering the surface clean and water-free.

What is the meaning of hydrophobicity?

Hydrophobicity is a term derived from a Greek term ‘hydro’ meaning water and ‘phobos’ meaning fear. Hydrophobic molecules (or hydrophobes) repel bodies of water and, owing to the fact that hydrophobes are non-polar, they attract other neutral molecules and non-polar solvents.

What is the reaction of a material's surface?

A material’s surface can react either in a hydrophilic (water-loving) or a hydrophobic (water-hating) manner.

What is the name of the product that absorbs water?

Another revolutionary product that uses the hydrophobic material is a sponge called ‘Obsorb’, which was developed by Paul Edmiston of the College of Wooster. This sponge is designed to absorb oils and solvents in water and grow to about eight times its weight.

Why do water drops come off surfaces?

Another extremely useful benefit of this is that as the water slides off, it also drags the surface dirt with it, rendering the surface clean and water-free.

Is Berghaus waterproof?

The DWR-coated down retained up to 80% of its loft after 3 min in water, meaning the jacket will not only be water-resistant but will also keep you warm.

What is hydrophobic substance?

A hydrophobic substance exhibits hydrophobicity and may be termed hydrophobic. Hydrophobic molecules tend to be nonpolar molecules that group together to form micelles rather than be exposed to water. Hydrophobic molecules typically dissolve in nonpolar solvents (e.g., organic solvents).

What does it mean to be hydrophobic?

To be hydrophobic means to fear water. In chemistry, it refers to the property of a substance to repel water. It isn't that the substance is repelled by water so much as it has a lack of attraction to it. A hydrophobic substance exhibits hydrophobicity and may be termed hydrophobic.

Why do nonpolar molecules clump together?

The structure is more ordered than free water molecules. The change in entropy (disorder) causes nonpolar molecules to clump together to decrease their exposure to water and thus decrease the entropy of the system.

What is the shape of water droplets on superhydrophobic surfaces called?

The shape of water droplets on superhydrophobic surfaces is called the Lotus effect , in reference to the appearance of water on a lotus leaf. Superhydrophobicity is considered a result of interfacial tension and not a chemical property of matter.

Is oil hydrophobic or hydrophobic?

Oils, fats, alkanes, and most other organic compounds are hydrophobic. If you mix oil or fat with water, the mixture will separate. If you shake a mixture of oil and water, the oil globules will eventually stick together to present a minimum surface area to the water.

Is olive oil hydrophobic?

Olive oil is hydrophobic. It doesn't mix with water and presents the minimum surface area to water. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. To be hydrophobic means to fear water.

Is hydrophobic the same as lipophilic?

While the terms hydrophobic and lipophilic are often used interchangeably, the two words don't mean the same thing. A lipophilic substance is "fat-loving." Most hydrophobic substances are also lipophilic, but exceptions include fluorocarbons and silicones.

What is hydrophobic chemistry?

Hydrophobic literally means “the fear of water”. Hydrophobic molecules and surfaces repel water. Hydrophobic liquids, such as oil, will separate from water. Hydrophobic molecules are usually nonpolar, meaning the atoms that make the molecule do not produce a static electric field. In polar molecules these opposite regions of electrical energy attract to water molecules. Without opposite electrical charges on the molecules, water cannot form hydrogen bonds with the molecules. The water molecules then form more hydrogen bonds with themselves and the nonpolar molecules clump together.

Why are macromolecules hydrophobic?

The hydrophobic effect is caused by nonpolar molecules clumping together. Large macromolecules can have hydrophobic sections, which will fold the molecule so they can be close to each other, away from water. Many amino acids in proteins are hydrophobic, helping the proteins obtain their complicated shapes.

Why are amino acids hydrophobic?

Many amino acids in proteins are hydrophobic, helping the proteins obtain their complicated shapes. The hydrophobic effect extends to organisms, as many hydrophobic molecules on the surface of an organisms help them regulate the amount of water and nutrients in their systems.

What are the molecules that make up the cell membrane?

Cell membranes are made of macromolecules known as phospholipids. Phospholipids have phosphorous atoms in the heads of the molecules, which attract water. The tail of the molecule is made of lipids, which are hydrophobic molecules. The hydrophilic heads point towards water, and the hydrophobic tails attract toward each other.

What are hydrophilic and nonpolar?

Related Biology Terms. Hydrophilic – Molecules or substances that are attracted to water. Polar – Molecules having static electric charges, which can interact with water. Non polar – Molecules that do not have static electric charges, and are much more likely to interact with other nonpolar molecular than with water.

How do birds get hydrophobic?

The birds brush the hydrophobic oils they secrete from their skin and special glands onto their feathers. When they dive underwater, the oils form a hydrophobic barrier that keeps water from penetrating. Then, when they emerge, they simply shake the water off and are able to fly.

Why are leaves hydrophobic?

It is important that rain and water are not absorbed through the leaves, as this would disrupt the flow of nutrients, which rely on the passage of water from root to leaf.

What is hydrophobic material?

Those that naturally repel water, causing droplets to form, are known as hydrophobic. Both classes of materials can have a significant impact on the performance of power plants, electronics, airplane wings and desalination plants, among other technologies, says Kripa Varanasi, an associate professor of mechanical engineering at MIT.

What is a surface that is superhydrophilic?

Though the definitions of these terms are less precise, surfaces where tight droplets form a contact angle of more than 160 degrees are considered superhydrophobic. If the droplets are spread out nearly flat, with a contact angle of less than about 20 degrees, the surface is superhydrophilic.

What are the new technologies that have contributed to the field of nanotechnology?

New technologies have also contributed to the field: The ability to create nanopatterned surfaces, with bumps or ridges just a few billionths of a meter across, has enabled a new generation of water-grabbing and water-shedding materials; new high-resolution imaging of surfaces in motion has enabled better understanding of the processes involved.

What is hydrophobic material?

A hydrophobic material is one that repels water. Inspiration for these materials tends to come from nature – for a long time the best hydrophobic materials worked on the same principle that allow lotus leaves to float on water without becoming waterlogged (the leaves have a rough surface that minimises the contact area between the liquid and solid). More recently, new materials have been developed by re-creating the nanopatterns on the wings of the Morpho butterfly which allow them to fly through rain undisturbed.

How to measure hydrophobicity?

The hydrophobicity of a material is generally measured by the ‘contact angle’ that a droplet of water makes with its surface . A droplet on a surface that is easily wetted will spread out and flatten, resulting in a very small contact angle, whereas a droplet on a hydrophobic surface will maintain it’s spherical shape, sitting on top of the surface with a contact angle of more than 90 degrees. The lotus leaf and butterfly wings mentioned above are examples of ‘super-hydrophobic’ materials, which are defined as having a contact angle of greater than 150 degrees.

What are some examples of omniphobic surfaces?

Nevertheless there are a few examples of omniphobic surfaces in nature, such as the collembola or springtail – a small wingless soil-dwelling insect.

How does superhydrophobicity help plants?

In many instances nature has used superhydrophobicity to allow plants and insect to survive under water for long periods of time. One example is Salvinia molesta, an extremely invasive fern that can survive underwater for weeks, continuing to photosynthesise. ‘It has the most complex surface we know in plants,’ says Barthlott. ‘No material scientist in their weirdest nightmare would have thought of such a solution!’ Its water-repellent surface holds a protective air layer via an array of whisk-shaped hairs (called trichomes) that make up the surface. The tips of the whisks are chemically distinct, being hydrophilic, and this firmly pins a water layer to the surface with air trapped underneath. The pinning effect keeps the air layer – as large as 3.5mm – under a negative pressure in small individual pockets.

What are the compounds that extrude waxy layers?

Barthlott says they are usually complex mixtures of long-chain hydrocarbons (20–30 carbons) which can be alkanes, ketones, aldehydes, alcohols, fatty acids and esters. 1 But it’s not only the chemistry that reduces wettability. ‘There is an enormous range of substances that can be used, ...

How to measure wettability of a surface?

The wettability of a surface is measured by the contact angle of a drop of liquid on the surface. This essentially measures how much of the drop is in contact with the surface – the higher the angle the smaller the contact with a surface. In the case of water, when this angle exceeds 150°, the surface is considered superhydrophobic and very difficult to wet.

How is crude oil extracted?

Large amounts of crude oil are now extracted from reservoirs using injected steam, but separating the resulting emulsion is difficult and requires materials that can function above 130°C. Banerjee has created an entirely new filtration process based on a stainless steel mesh coated with zinc oxide nanotetrapods.

What is the function of rough hierarchical surfaces?

The function of the rough hierarchical surface is to create air pockets. A water droplet sits on top of the trapped air and this drastically reduces the contact between solid and liquid, allowing the droplets to form near perfect spheres which easily roll off. One of the most famous examples of this behaviour is the lotus leaf, whose self-cleaning surface has a contact angle approaching 180°. Scanning probe microscopy shows the leaves are covered with 1–5μm bumps called papillae underneath a waxy crystalline top layer. This means rain drops will roll off, along with any surface dirt.

Do plants and animals have non-stick surfaces?

Numerous plants and animals have surfaces designed to repel water, and in some instances even oil. But the chemistry of these surfaces is not nature’s only trick – complex nanostructuring plays a huge role. Exploiting these designs is now helping chemists to produce the next generation of non-stick coatings.

Why are superhydrophobic surfaces used?

Consequently, superhydrophobic surfaces are being pursued as antibacterial coatings to reduce infections using the entrapped air layer to inhibit adherence. Unlike many of the other applications discussed thus far, antibacterial suppression is necessary for a short duration after implantation. There is a critical period of hours-to-days where bacterial binding and growth must be suppressed to allow cell and tissue integration to occur [166]. Many of the approaches employing superhydrophobic materials are reviewed by Zhang et al. and the reader is referred to this article [167]. Crick et al. [168] fabricated a superhydrophobic surface from a silicone elastomer using aerosol-assisted CVD. When compared to flat glass surfaces or flat silicone surfaces, counts of both Escherichia coli ( E. coli) and Methicillin-resistant Staphylococcus aureus ( S. aureus) are reduced after submersion in the bacterial broth for 1 h. S. aureus showed significantly less growth on superhydrophobic surfaces (2.5-fold lower), and E. coli showed slightly less than either control (1.6-fold lower). Loss of air may account for the small amount of bacterial growth suppression observed. Tang et al. [169] used flat TiO 2 surfaces and calcined to form TiO 2 nanotubes, and coated both with perfluorooctyl-triethoxysilane (PTES) to form superhydrophobic and hydrophobic surfaces. The superhydrophobic surfaces resisted S. aureus adhesion compared to unmodified nanotubes and the flat hydrophilic titanium surfaces. Loo et al. [170] showed the delayed growth of bacteria on polyvinyl chloride (PVC) endotracheal tubes with texturing of the surfaces. A rough microstructure PVC with micron-sized features is prepared using a controlled precipitation method via selection of appropriate solvent combinations. Smooth PVC surfaces showed Pseudomonas aeruginosa binding within 6 h and subsequent biofilm formation. With the superhydrophobic textured PVC surfaces, binding and biofilm production did not occur until 18–24 h ( Fig. 7 ). After 96 h, extensive growth is observed on all surfaces, with only a small amount of suppression on superhydrophobic surfaces. The authors state that the air layer at superhydrophobic surfaces is likely fully removed by 96 h.

What is the function of superhydrophobic surfaces?

Fig. 8. Superhydrophobic surfaces allow deposition of molecules on a small number of pillars during evaporation (a, b, c). Concentration of non-volatile components at pillars allows detection of femto-to attomolar concentrations of biomolecules with an appropriate plasmonic structure on the pillars. Adapted with permission from Ref. [196].

What is switchable wetting?

Surfaces with switchable wetting are also being investigated for diagnostics applications. Shiu et al. [193] demonstrated the ability to switch a surface from superhydrophobic to complete wetted with application of an applied electric field (electrowetting), allowing an array of protein microspots to selectively form. Before application of the electric field, protein binding is inhibited, allowing protein binding to be turned on or off. A widely investigated material for stimuli-responsive wetting is TiO 2, because under UV irradiation it exhibits photocatalysis and generates hydroxyl groups to make a rough surface superhydrophilic [35]. Meng et al. [194] employed surfaces with rough TiO 2 nanostructure to capture cells and adhere antibodies for diagnosis. The TiO 2 surfaces can be reused by photocatalytic cleaning under UV light to afford the original properties. The authors demonstrated four cycles of this process while maintaining the same cell capture efficiency and complete removal of protein as measured by immunofluorescence. Long-term maintenance of superhydrophobic materials may require this type of periodic cleaning cycle. Another diagnostic with responsive wetting is the pressure-deformable membrane reported by Seo et al. [195]. The authors fabricated an elastic, 275 μm thick PDMS membrane textured with ∼2 μm wide pillars, and demonstrated that the curvature created by applying vacuum altered the local contact angle. This process can then be used to drive droplet flow and merging, as well as mixing of reagents (e.g., siRNA and synthetic delivery vectors) to prepare supramolecular structures for effective siRNA transfection.

How does superhydrophobic surface prevent protein adsorption?

The use of superhydrophobic surfaces for preventing protein adsorption utilizes a unique strategy to those previously mentioned through maintenance of an air layer at the material surface. This air layer at the interface limits the available water-material surface area and decreases the total area available for protein binding. This is the first step in biofouling, the prevention of which has been the subject of multiple reviews [84], [126], [127]. Work by Leibner et al. [128] nicely contextualizes the use of superhydrophobic surfaces for biomedical applications, and the conflicting design criteria that are required for their use. Their work focused on the adsorption of human serum albumin to commercially available expanded polytetrafluoroethylene (ePTFE). When entrapped air is maintained within the highly hydrophobic ePTFE matrix, little or no adsorption of albumin from phosphate buffered saline (PBS) is detected on the material surface. However, when air is removed from the ePTFE material, albumin is adsorbed to the entire material surface, including the portion of the surface that once housed air. Huang et al. [129] showed similar results, where a templated superhydrophilic-superhydrophobic structure comprised of TiO 2 nanotubes exhibited suppression of protein binding when air is present in the superhydrophobic regions. Removal of the air layer increases protein binding, as shown in Fig. 3. Work by both sets of authors demonstrates that superhydrophobic surfaces support an entrapped air layer to initially prevent protein binding, but removing the air “reveals” a high surface area material that adsorbs larger quantities of protein to the surface.

What happens when a cell binds to a superhydrophobic surface?

Cells that bind superhydrophobic surfaces form a round morphology with few cellular projections. After several days of incubation and growth, cell contractility, reorganization of FN at the cell surface, and cell proliferation are all reduced on superhydrophobic surfaces compared to non-superhydrophobic surfaces.

Why are metastable materials being investigated as delivery platforms?

Metastable superhydrophobic materials are themselves being investigated as delivery platforms because the rate of wetting controls drug release from the material. In general, drug delivery from electrospun fibers is an active area of research and techniques for electrospinning nanofibers are reviewed by Hu et al. and Chou et al. [215], [216]. Reports from our laboratory [76], [77], [78], [217], [218] describe the fabrication and characterization of superhydrophobic 3D materials as drug delivery devices. By varying the stability of an entrapped air layer within these 3D materials, the rate of drug release is controlled.

What are the nanostructures of Taro leaves?

Ma et al. [171] demonstrated that the nanostructures on the Taro leaf, which impart superhydrophobicity, are responsible for its resistance to P. aeruginosa adhesion. They attribute this to the microstructures on the “papilla” which trap air at the surface and prevent binding. When the leaves are wetted with ethanol to completely remove the air layer, bacteria binding increased on the surface although the wax crystals present on the leaves still suppressed bacterial growth even when wetted. Epidermal cells between the wax crystals showed extensive growth with removal of the protective air layer. Pernites et al. [172] manufactured superhydrophobic surfaces by depositing PS particles on a surface with subsequent electropolymerization of conductive polythiophene on top to produce a rough superhydrophobic surface. Without an electric field, the films are resistant to fibrinogen and E. coli binding. When an electric field is used to remove the air layer (electrowetting), attachment of both fibrinogen and E. coli is enhanced.

Material Properties of Hydrophobic Materials

How to Make A Hydrophobic Material

• Hydrophobic materials can be created using two methods. The simpler method is to coat a surface with wax, oil, or grease. The other is using nanoengineering to help create a unique, nanopatterned textured surface. The nanopatterns consist of small bumps that have a width of 10 µm. Researchers at MIT have taken this to another level by coating a nan...

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