Hydrophobic Plasma Coatings

Hydrophobic plasma coatings are a sub-category of plasma surface functionalisation, the specific precursor being chosen to produce a permanent, low surface energy layer on the material or part being treated. The hydrophobic surface is typically less than 1/100th thickness of a human hair, colourless, odourless and doesn’t affect the look or feel of the material in any way.

Permanent hydrophobic surfaces are rapidly finding new applications all the time. Liquid repellent coatings currently enhance products in the textile, medical device, opthalmic and consumer electronics industries to name but a few.

In plasma coating a nano-scale polymer layer is formed over the entire surface area of an object placed in the plasma. The coating process takes just a few minutes. The coating produced is typically less than 1/100th thickness of a human hair, colourless, odourless and doesn’t effect the look or feel of the material in any way. It is a permanent coating too, being bound to the material surface on an atomic scale.

Plasma coatings are one of the most exciting areas of plasma technology, offering enormous potential to enhance a material’s function and value over a wide range of applications. They deliver two main categories of surface property: totally liquid (water & oil) repellent, or totally wettable.

liquid repellent Plasma Coatings

Specific treatments render surfaces totally water repellent to water, solvents and oils as shown below in the example of cotton that has been plasma coated.

A water droplet totally absorbed by a sample of tissue prior to plasma treatment A water droplet totally repelled by a sample of tissue after permanent coating deposition as a result of plasma treatment

How Plasma Coatings Work

Monomers are introduced with the plasma feed gas. Monomers are small molecules which will, under the correct conditions, bond together to form polymers. Plasmas create the right conditions at the surface of the material for this to happen both quickly and efficiently. Different monomers are used to produce hydrophobic and hydrophilic surfaces.

An illustrative example of a piece prior to plasma coatingAn illustrative example of a piece during plasma treatment polymerisationAn illustrative example of a piece with a deposited layer, after the plasma coating has been applied

Plasma coating is suitable for:

  • general plastics and rubber
  • performance textiles
  • filtration media
  • metals, glass, ceramics and composites
  • medical plastics
  • consumer electronics plastics
  • automotive components
  • aerospace components