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Material Coatings: How to Make a Part Surface Hydrophobic

Written by: George Osenga

There is often a question by manufacturers of how to make a surface of a part hydrophobic.  Plasma coating with a PTFE-like material using a plasma system with a monomer of choice is a viable solution.  A Monomer can be selected by a manufacturer in order to facilitate the best and most cost-effective solution.

What is a hydrophobic surface?

A hydrophobic surface is defined as a surface that has very low surface energy.  This means fluids do not wet or bond to a surface.  This means there are no molecular forces holding fluid to a surface, and charge related forces are very weak or low strength.  If glue or a coating were applied to a hydrophobic surface and allowed to dry or cure.  Resulting coating would easily be removed or peeled off.  A lack of bonding forces between a base material and your application fluid produces little to no adhesion.  

A surface that is hydrophobic in nature will often have other properties as well such as corrosion resistance, chemical resistance, electrically insulated, and low surface energy.  These are sometimes favorable properties that a manufacturer will look to optimize in their materials.

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The benefits of hydrophobic coatings

Many materials will not have the hydrophobic property with a desired base material on its own.  In this application a coating is used to achieve hydrophobic surface performance.  This thin layer can provide a barrier layer on a surface which will limit the rate that a liquid or a gas can penetrate or pass through a base material of a part.  These coatings are desirable in materials for applications such as containers for food, chemical, and biological applications to eliminate interaction between a container and materials within them.

Manufacturers will also use hydrophobic coatings to obtain scratch resistance or protective coatings on their parts.  These coatings can have better hardness or material wear characteristics than a standard polymer material.  This is a common practice in the automotive and communications industries.  

Hydrophobic coatings are also used in the biotech and pharmaceutical industries where instruments need a hydrophobic coating inside to prevent test chemicals from remaining inside the instrument.  An example would be to apply the coating on the inside of a pipette to ensure all test material or process chemistry is expelled from your pipette in order to provide more accurate sample measurements and minimize downstream chemistry drag out or transfer.

The electronics industry is also a significant user of hydrophobic coatings.  These are used for electronic printed circuit boards to make them water resistant to minimize damage by water or other wet contamination.

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Benefits of using plasma deposition to apply a hydrophobic coating

There is often a challenge in adding a precise hydrophobic coating to a material.  By plasma depositing coatings using a monomer or polymerizing gas as the volatilized gas feedstock in a plasma system, this will produce a polymer coating at a very precise rate or thicknesses from 10 nm to 10 micrometers thick.  Benefits from this approach are that coatings can be very thin and uniformly applied to parts or materials.  When a plasma process is used to apply a coating a very repeatable, higher quality, reliable product can be produced.  These coatings are also often resistant to chemical, mechanical, and thermal degradation.  

Manufacturers like to apply a hydrophobic coating using a plasma system because it provides many advantages to observed properties of the surface of their parts and products without changing the aspects of a base or bulk material.  Plasma coating provides better quality coatings than other conventional coating methods and is free from potential material contamination.  Since plasma processing is performed in a sealed environment (vacuum chamber), process materials are free from outside contamination and your process is isolated from operators which provides good industrial hygiene.

Interested in learning more about how coatings enable manufacturers to improve the quality of their products? Please consider downloading our eBook titled "The Manufacturer's Plasma Coating Playbook" to learn about Hydrophobic surfaces and other coating applications. If you are interested in speaking to an expert in plasma applications, please consider reaching out and scheduling a plasma treatment overview discussion

The Manufacturer’s Plasma Coating Playbook

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