Technology

The work at HygraTek® is focused on developing coatings that preferentially attract or repel different liquids. There are three main areas of focus in our work:

1. Durable omniphobic surfaces
2. Icephobic surfaces
3. Hygro-responsive membranes

Surfaces that display contact angles greater than 150° along with low contact angle hysteresis with essentially all high and low surface tension liquids, including water, oils and alcohols, are known as superomniphobic surfaces. Such surfaces have a range of commercial applications including self-cleaning surfaces, non-fouling surfaces, stain-free clothing, drag reduction, corrosion prevention, and separation of liquids.

At HygraTek we have developed some of the most durable, and economical, superomniphobic surfaces. The developed coatings can repel non-Newtonian liquids (e.g., viscoelastic polymer solutions) in addition to a wide range of Newtonian liquids including concentrated organic and inorganic acids, bases and solvents. Virtually all liquids – organic or inorganic, polar or non-polar, Newtonian or non-Newtonian – easily roll-off and bounce on our surfaces, thereby making our surfaces ideal candidates for effective chemical shielding. We have also developed one of the first methodologies for the fabrication of flexible, highly transparent (optical transmission >90%), superomniphobic surfaces that can repel a range of low and high surface tension liquids.

HygraTek® has developed a patent-pending approach to create superomniphobic surfaces with following characteristics:

• Contact angle (CA) ≥ 150 and contact angle hysteresis (CAH) < 4 for essentially all liquids (water, alcohols, acids, bases, oils etc.)
• Thin layer superomniphobic coating has minimal weight gain (< 0.3 % of the substrate weight)
• Superomniphobic surfaces are stable between -50ºC and 250ºC
• Can be easily applied by contractors with fast curing time (< 3 h)
• Exhibits excellent durability and abrasion resistance based on Taber abrasion results
• Highly insulating and non-conducting
• Minimal maintenance, cost-effective compared to other products in market

The durable superomniphobic surfaces developed by HygraTek® are extremely unique. The coating can be sprayed-on, dip-coated, spin-coated or etched onto virtually any substrate, enabling applications from stain-resistant textiles, drag-reduction, biofouling prevention, corrosion prevention, and chemical/biological protection.

Our coatings can even be an excellent solution for improving the high voltage, wet-limit performance and longevity of different dielectric and conducting materials used in Very Low and Low Frequency (VLF/LF) antenna components.

Ice accretion and subsequent removal is a safety hazard for aircrafts, power lines, motor vehicles, marine structures, communication towers and wind turbines. The most common methods of ice removal are extremely energy intensive. Mechanical removal, electro-mechanical expulsion, thermal removal and chemical removal are the industrial standards of today. Each method involves either inputting enough force to break off any accreted ice, or inputting enough energy to melt the ice. Thus, there exists a strong need to develop passive, energy-efficient methods for the removal of ice from any surface.

The adhesion between ice and many materials has been extensively studied. To quantify the ice adhesion strength of a material, a known area of ice, frozen on the material, is sheared off, and the practical work of adhesion, W_a (also called the ice-adhesion strength) is measured. Most common metals like aluminum or steel have extremely high ice adhesion strengths, of W_a ~ 1400 kPa, respectively. On the other hand, polymers, such as Teflon, display ice-adhesion strengths of W_a ~ 240 kPa. Based on traditional predictions, the best ice-phobic surfaces should possess ice-adhesion strengths of W_a ~ 100 kPa.

In our work we have circumvented the theoretical lower limit of ice adhesion strength, discovering a new physical phenomenon that allows us to create icephobic coatings with ice adhesion strengths as low as 0.2 kPa. Our coatings show a ~300 fold reduction in W_a over plain aluminum metal, and a 400% reduction in W_a over any other published value of W_a. Further, even after repeated icing – de-icing cycles, extensive Taber abrasion, thermal cycling, salt exposure, and acid/ base exposure, the ice adhesion strength of our coatings is maintained, both in laboratory settings and even in Michigan wintery conditions over several months of exposure.

There is a critical need to develop new energy-efficient solutions for the separation of oil-water mixtures, including those stabilized by surfactants. Traditional membrane-based separation technologies for oil-water mixtures are energy-intensive and further limited, either by fouling or the inability of a single membrane to separate all types of oil-water mixtures. The ideal membrane to effect gravity-driven separation of oil-water mixtures is expected to be both hydrophilic and oleophobic, in air and when submerged under water. Such membranes would allow the higher density liquid (water) to flow through, while retaining the lower density liquid (oil). However, as water possesses a significantly higher surface tension than various oils, most membranes that prevent the permeation of oils, also prevent the permeation of water.

At HygraTek, we have developed the first-ever reconfigurable membranes that, counter-intuitively, are both superhydrophilic (i.e., water contact angles @ 0°) and superoleophobic (i.e., oil contact angles > 150°). These membranes were designed through the systematic tailoring of membrane porosity and the membrane-water interfacial energy. The developed fouling-resistant membranes are able to separate all types of oil-water mixtures, with > 99% separation efficiency, using a single membrane. The developed membranes can be used for the continuous, solely gravity-driven separation of surfactant-stabilized oil-water emulsions, with a separation efficiency ³ 99.9%.

Our coatings can be applied onto any existing porous substrate, such as filter papers, paper, fabrics and wire-meshes. The developed membranes enable solely gravity driven clean-up of oil spills, and the energy efficient separation of a range of different emulsions produced during waste-water treatment, fracking, chemical synthesis, and produced water disposal. Beyond this, our membranes can also be used to maximize water re-use and prolong membrane life, enhancing your return on investment (ROI).