They say opposites attract, not so when comparing hydrophobic and hydrophilic surfaces. Put the two together and you're either all wet or dry as a bone. We compared coated surfaces and the benefits of moisture management. Here's what we learned.
How To Make a Surface Hydrophobic or Hydrophilic?
In this blog post you will learn:
A hydrophobic surface is a water repelling, low surface energy surface that resists wetting. Moisture contact angle measurements will classify a surface as hydrophobic when the contact angle of the water droplet exceeds 90 degrees. Exceed the 150 degree contact angle mark and the surface will be classified as superhydrophobic. Water will jump right off the surface as seen in this video.
There are many benefits of a moisture repelling surface. They include:
|Surface icing prevention||Condenser & evaporator fouling prevention|
|Improved corrosion resistance||Prevent moisture contamination in heat trace tubing|
|Produced water filtration & management||Improved reliability in continuous emissions monitors (CEMS)|
|Improved moisture detection instrumentation||HPLC medical diagnostics improved separation & corrosion resistance|
|Manage moisture contamination in liquid natural gas systems||Prevent contamination in analytical sample transfer systems|
Have a question about this blog or controlling moisture resistance? Click the box below to discuss your application with one of our coating scientists.
Not to be outdone, hydrophilic surfaces have benefits as well. What are hydrophilic surfaces? They are high surface energy substrates that attract water and allow wetting of the surface. They typically have a droplet contact angle measurement of less than 90 degrees. Lots of surfaces tend to be more water friendly including, glass, steel, or stainless steel and many coatings and paints. Of course test results can depend on the surface roughness and surface energy of the material you're testing.
Benefits of a moisture friendly surface include.
|Improved separation in medical diagnostics (application dependent)||Improved efficiency in heat transfer devices & heat exchangers|
|Improve acceptance of In-body devices||Improve surface interaction in filtration devices (application dependent)|
Achieving the Desired Water Repelling Property
How do I get a surface to match my desired moisture level of moisture resistance?
You don't have to make a super radical change to material or product construction in order to change the moisture performance. Fortunately we offer silicon barrier coatings with a wide range of water management capabilities.
Want a more corrosion resistant or inert coating with a low surface contact angle? Try SilcoNert® 1000 or Silcolloy®. If you're looking for an inert coating that's not too moisture repelling, go with SilcoNert® 2000. Need a hydrophobic coating or superhydrophobic coating? Dursan® or our new Notak® coating may do the trick. Note, that our Notak coating is in pre-production Beta testing so we have limited capacity for that coating. Contact our Technical Service Team to discuss your application and we'll be happy to make a coating recommendation.
The lower a coating's surface free energy, the higher the contact angle. For example, our new Notak coating process when applied to aluminum or stainless steel will reduce the surface free energy by up to 84%. Learn more about Notak, get our Notak Data Sheet.
The comparative graph above highlights the water repelling properties of each of our coatings compared to stainless steel; each coating has specific applications and benefits. Go to our applications guide to get the lowdown on each of our coatings.
Oleophobic Surfaces: It's Not All About Water
Low surface tension liquids like oil or organic solvents are designed to wet the surface for maximum lubrication or solvation. But what if you're separating organics or don't want the surface to wet? Water repelling materials like PTFE aren't effective in repelling oil. Here's what oil and hexadecane look like when placed on a PTFE surface.
We bonded our new Notak® fluoro material on a rough stainless steel surface to see if the contact angle would increase. Notak made a big difference in contact angle, making the stainless steel oleophobic surface.
Given the nature of refining or cleaning for that matter, we can expect the surface to be exposed to elevated temperatures. PTFE is high temperature limited and can fail in many high temperature applications. We exposed the Notak surface to elevated temperature (300°C) for several hours to gauge the impact to wettability and contact angle on various surfaces. The graph below shows consistent contact angle readings over the 90+ hour test. PTFE would have failed at 250°C.
The contribution of surface energy and it's relationship to process fluids can have far ranging impacts. Surface interaction can impact corrosion, fouling, analytical sampling results, filtration and medical device performance. So it's important to understand how to manage the energy of critical flow path surfaces.
Get some really informative and helpful tips on ways to prevent fouling, change surface energy, & improve surface performance, click the box below to watch our webinar about water repelling and and anti-fouling surfaces.