Defined: Hydrophilic, Hydrophobic, Oleophilic, Oleophobic, Hygroscopic

When discussing enhanced materials we often use terms like “hydrophilic/hydrophobic” and “oleophilic/oleophobic.” Just what do these terms mean exactly? Let’s take a quick look.

• Hydrophilic − Refers to substances that absorb water. A hydrophilic substance will bond, on a molecular level with water.
• Hydrophobic − Refers to materials that will repel water.
• Oleophilic − Refers to a substance that absorb oils or nonpolar liquids.
• Oleophobic − Refers to a substance that repels oils or nonpolar liquids.
• Hygroscopic − Refers to the ability of a material to absorb humidity from the air. A hygroscopic substance will actively attract and absorb water, without bonding. (A hygroscope is an instrument that indicates changes in humidity.)

Water is itself hydrophilic (it mixes with more water easily) and oils or fats are generally hydrophobic and will separate from water, forming an oily layer.

Note: The suffix "philic" means loving or attracted to. The suffix "phobic" means fear or fearful.

There’s a lot more to learn, but this is certainly a useful place to start. If we can help you sort these terms out or provide information on how to modify materials to enhance (or suppress) any these characteristics, please do not hesitate to reach out to our experts.