Water contact angle

The water contact angle, often simply referred to as the water contact angle, is a fascinating phenomenon that describes the interaction between a water droplet and the surface of a solid. It gives us deep insights into the properties of surfaces and helps us understand how liquids react on different materials.

When you drop a drop of water onto a surface, that drop either stretches out or stays in a spherical shape. This behavior is determined by the water contact angle. The higher the angle, the less the water drop adheres to the surface. This is closely related to the surface energy of the solid: a high water contact angle indicates a low surface energy.

If the water edge angle is greater than 100°, it indicates that the surface is non-stick. Such surfaces are desirable for rain jackets, shoes or cookware, for example, as they prevent water from sticking to the surface.

Measuring the water contact angle can also help check the quality of surface coatings, test the effectiveness of cleaning agents or evaluate the efficiency of non-stick coatings.

But how exactly is the water contact angle measured? Specialized instruments, often called goniometers, are used to determine the precise angle at which a drop of water rests on a surface. This angle is then analyzed to draw conclusions about the properties of the surface.

It's fascinating to see how this seemingly simple concept has so many practical applications in modern technology and industry. From developing water-repellent clothing to optimizing coatings for medical devices, the water contact angle plays a crucial role in many areas.