The term Hydro means water. Therefore, it can be said that the study of hydrophilic and hydrophobic molecules deals with the solubility and properties of these materials as they link to and interact with water. The two terms may seem to be the same, but they are actually opposites.
The word ‘phobic’ has been derived from the word ‘phobia’, which means fear. Hence the term hydrophobic means fear of water.
The term ‘philic’ has been derived from the word ‘philia’ which means friendship. Hence the term hydrophilic means loving water.
Thus, hydrophilic materials are those that link well with water, whereas hydrophobic molecules are those that do not interact well with water. The difference between hydrophilic and hydrophobic materials is drawn by observing their reaction towards water, either attraction to water or repellency of water.
For example, we can see that there are a few solubles that get absorbed in water, while there are few that do not. Salt can get dissolved in water easily, whereas powdered makeup cannot. Salt
On the other hand, does not get absorbed in oil, which is a hydrophobic liquid, whereas powdered or crushed makeup can get dissolved in oil.
Thus, it can be said that powdered makeup is hydrophobic, whereas salt is hydrophilic.
Hydrophilic vs Hydrophobic
The main difference between Hydrophilic and Hydrophobic materials is that the hydrophilic materials are water-loving or water attractive. The hydrophilic molecules attract water. On the other hand, the hydrophobic materials are water-repelling or water-hating. The hydrophobic molecules repel water.
Comparison Table Between Hydrophilic and Hydrophobic
| Parameter of Comparison | Hydrophilic | Hydrophobic |
| Meaning | It means water-loving or having a strong inclination towards water. | It means being resistant to water or avoiding water. |
| Molecules | The hydrophilic molecules are called hydrophiles. | The hydrophobic molecules are called hydrophobes. |
| Interaction with water | The hydrophilic molecules attract water. | The hydrophobic molecules repel water. |
| Polarity | Hydrophilic molecules are polar. | Hydrophobes are non polar. |
| Reaction | Dissolving the hydrophilic molecules in water is an exothermic reaction. | Dissolving the hydrophilic molecules in water is an endothermic reaction. |
What is Hydrophilic?
The word Hydro means water. The word ‘philic’ has been derived from the word ‘philia’ which means friendship. Thus the word hydrophilic means loving water.
Hydrophilic molecules that are known as hydrophiles are molecules that attract water. Hydrophilic molecules are polar in nature.
Application of Hydrophilic molecules:
The hydrophilic molecules are largely used in a number of fields, such as chemistry, physics, food, engineering, paint, drug delivery, paper, textiles, biomedical, pharmaceuticals, water treatment, constructions, coatings, adhesives, thickeners, film formers, gallants, stabilizers, dispersing and suspending agents, humectants, flocculants, personal care, lubricants and binders, detergents, mineral processing, building products, and oil field products.
Examples of hydrophilic substances:
There are a large number of hydrophilic substances, such as starch, salt, sugar, keratin, protein, cotton, cellulose, wool, silica, alcohols, polyethylene glycol ethers, polyvinyl alcohol, gelatin, inulin, guar gum, albumin, chitosan, xanthan gum, agarose, pectin, agar, dextran, algin, carrageenan and so on.
What is Hydrophobic?
The word Hydro means water. The term ‘phobic’ has been derived from the word ‘phobia’, which means fear. Hence the term hydrophobic means fear of water.
Hydrophobic molecules that are known as hydrophobes are molecules that repel water. Hydrophobes are non polar in nature.
Application of Hydrophobic molecules:
The hydrophobic interactions have an important role in many fields, such as oil-water separation, self-cleaning, antibacterial, corrosion resistance, anti-icing, protein folding, chemical separation process, management of oil spills, separation of non-polar elements from polar elements and so on.
Examples of Hydrophobic substances:
A large number of hydrophobic substances can be seen in both the industrial and the domestic sectors. Greasy compounds, fats, oils, alkanes and most of the organic compounds are examples of hydrophobic substances. Other examples of hydrophobic substances include hydrophobicity in plants and animals. A large number of plants are hydrophobic, which means that there is a presence of hydrophobic coatings on the leaves surface.
Hydrophobicity can be seen in birds as well and it plays a vital role. The hydrophobicity in the feathers and bodies does not allow water penetration in the bodies and thus helps to avoid weight gains and helps them in flying smoothly.
Main Differences Between Hydrophilic and Hydrophobic
- Hydrophilic means having harmony with water or water-loving. On the other hand, Hydrophobic means resistance to wetting.
- Hydrophiles are the hydrophilic molecules, whereas hydrophobes are the hydrophobic molecules.
- Hydrophiles get dissolved or absorbed in water. Hydrophobes do not get dissolved in water, but only get absorbed in oil-based substances.
- Hydrophilic molecules are ionic and polar, while Hydrophobic molecules are nonpolar.
- When the hydrophilic molecules are added to water, the entropy gets increased. When the hydrophobic molecules are added to water, the entropy gets decreased.
Conclusion
When water hits a surface, it either spreads evenly or pearls into tiny drops.
These properties have been noticed by people for many years, and a proper understanding of such properties could help bring new applications.
The property that focuses on maximum contact, which has a strong inclination towards water is hydrophilic. The property that causes drops to be formed, and repels water, is hydrophobic.
The hydrophobic and hydrophilic properties are differentiated based on the geometry or formation of water on a surface, mainly the contact angle. It is the angle between the flat surface and the edge of the droplet.
The difference between Hydrophilic and Hydrophobic molecules is its interaction with water. The hydrophilic materials are water-loving. The molecules attract water. On the other hand, the Hydrophobic materials are water-hating. They repel water.Hydrophilic molecules get absorbed or dissolved in water easily, whereas Hydrophobic molecules do not get absorbed in water. Salt, sugar, cellulose, starch are examples of hydrophilic molecules.
References
- https://pubs.rsc.org/en/content/articlehtml/2001/gc/b103275p
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.96.186101