Hydrophobic substances, those that repel water, play a fundamental role in the development of new materials with improved properties. Proof of this is that in the last decade there has been a multitude of studies aimed at their research. In this article, we explain what a hydrophobic material is and its industrial applications.
What are hydrophobic substances?
Hydrophobic materials are those based on the chemical concept of hydrophobicity, i.e. the ability of the substance to repel water.
Hydrophobicity is a term derived from the Greek “hydro”, meaning water, and “phobos”, meaning fear. Hydrophobic substances are composed of non-polar molecules that repel bodies of water and attract other neutral molecules and non-polar solvents.
Examples of these molecules are alkanes, oils and fats in general.
Water droplets on hydrophobic surfaces have a characteristic shape that is called the lotus effect, after the appearance of water on a lotus leaf.
These types of surfaces occur in nature, such as the wings of butterflies or the feathers of ducks, which are used as a reference for the creation and innovation of hydrophobic materials.
To understand the behavior of a surface against water, its contact angle must be measured, which will provide information about the interaction energy between the surface and the liquid. Hydrophobic substances are characterized by a contact angle with water greater than 90°. However, there are also superhydrophobic materials, which have angles greater than 150º and whose surfaces resist wetting.
Applications and uses of hydrophobic material
When oil or fats are mixed with water, two distinct layers are formed that will be immiscible with each other, since water is polar and fats are not. Some of the best known applications of hydrophobic substances are related to this phenomenon.
For example, processes for the removal of fats from aqueous solutions, the management of oil spills and the chemical separation of polar and non-polar elements.
However, hydrophobic substances perform many other essential industrial functions. In this respect, superhydrophobic coatings are used in everything from automotive, commercial, aerospace, alternative energy, construction, technology and even for the development of new materials of the future.
Hydrophobic and superhydrophobic substances can be designed using many manufacturing methods, such as layer-by-layer assembly, laser processing, solution immersion, sol-gel techniques, chemical etching and the Hummers method.
The usefulness of this property is really significant. For example, there is a wide variety of hydrophobic coatings that improve the performance and service life of materials.
Some of the industrial uses of hydrophobic materials are:
- Removal of oil from aqueous solutions.
- Removal of oil from aqueous solutions applied to plastics, ceramics and mesh.
- Strong self-cleaning effect and creation of new materials by surface modification in plastics, heat pipes, metals, textiles, glass, paints and electronic components.
- Improved antifreeze behavior of heat pipes.
- Functions as a protective coating against water and dust on electronic products.
- Plays an essential role in water treatment.
- Heat transfer applications
- Improving the functionality of biomedical devices, etc.
Advantages and Properties of Hydrophobic Substances
The use of hydrophobicity generates many advantages.
Hydrophobics are typically low-energy surface materials that resist wetting and have increased corrosion resistance.
These substances are used to improve moisture detection instruments and to prevent moisture contamination in heat tracing tubes and analytical sample transfer systems. For example, we can use hydrophobic substances in medical diagnostic systems to improve separation and corrosion resistance.
Similarly, hydrophobic surfaces are used in the manufacture of paints for their antibacterial action, as well as in metal refining, in stain-resistant textiles or in the manufacture of flame-retardant and waterproof clothing.
In addition, hydrophobic materials made from polymers are widely used because of their low cost and simple preparation.
We can conclude that, given the success of hydrophobicity, a great deal of research is currently being carried out focused on the development of new superhydrophobic materials, which are considered to be one of the materials of the future.
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