While both hydrophobic and hydrophilic coatings can be utilised to reduce surface friction, there are key differences between the two to help determine which is the best option for your circumstances.
The key difference can be understood by looking at the meaning of the two words:
hydrophobic = as a literal translation, this means ‘water fearing’ but in a practical sense it relates to a surface having the ability to repel water meaning that there is essentially no interaction between water molecules and hydrophobic surfaces, known to be non-polar.
hydrophilic = literally translates as ‘water loving’, which means these surfaces can attract and interact with water molecules, hydrophilic substances are said to be polar.
When it comes to determining whether a surface is hydrophobic or hydrophilic, it is the contact angle of water on the surface that helps to define this – contact angle refers to the angle between the edge of a droplet and the surface it is on. A hydrophobic surface will have a contact angle of more than 90 degrees as the surface attempts to repel the water droplet, this will usually lead to any water remaining in a spherical shape on the surface. On the other hand, a droplet on a hydrophilic surface will have a contact angle of less than 90 degrees due to the surface interacting with the fluid and this can be shown by water spreading across the surface.
In terms of usage of the two different coatings, due to the key feature of hydrophobic surfaces being their ability to repel water, this means that they can be a good choice to be implemented in cases where non stick properties are required or can also be used for instances where a product needs to be waterproofed. The main area where hydrophilic coatings come into use is within the medical industry – coating medical equipment and needles with a hydrophilic coating gives greatly reduced friction between the equipment and the patient’s skin/body, this can help to make insertion much easier and also lowers the chance of procedures causing unnecessary discomfort.
Whatever your requirements, our years of industry experience mean we can help you ensure that the best possible coating for your needs is used. Get in touch with one of our specialists to find out how we can help.