The lotus effect (Day 195)

The lotus effect (Day 195)

8th December 2014

It's always good to hear of research receiving a funding boost and in this case the well-deserved recipient is the Karlsruhe Institute of Technology (KIT) in Germany, who are about to benefit from €2.85 million (£2.25 million).

The money will go towards the further development of 'Fluoropore' - a new class of highly fluorinated super-repellent polymers which makes both water and oil droplets roll off.

Most coatings by design are invisible, yet offer benefits that are very evident. Keeping shoes dry, protecting ships from ice build-up, the free flow of blood via medical devices, even simply frying an onion are made easier with the right coating.

It's amazing to think that DuPont's Teflon® coating has been around since 1938 and is still used widely in products such as in paints, fabrics, carpets, home furnishings, clothing and more.

Fluoropore appears to be equally flexible and universal with potential applications including keeping cars clean, preventing graffiti and keeping mud off clothing and footwear.
The novel material “fluoropore” repels water (left) and oil (right). These droplets do not adhere to or wet the surface. (Photo: KIT/Rapp)

The coating is the work of a multi-disciplinary team, including chemical engineers, led by Bastian Rapp of the KIT Institute of Microstructure Technology.

The inspiration for the project is drawn from special adaptations found in nature such as lotus plants and the leaves of cabbages, which repel water - the droplets simply roll off.

Science can already mimic the classical 'lotus effect' by producing rough surfaces with special chemical properties.

But as Bastian explains: “... this trick does not work for oils – the lotus plant repels water, but not oil.

“Oil-repellent surfaces need to have another chemical structure, fluoropolymers are required for this purpose.."

Fluoropolymers are high-performance plastics with a high heat resistance and chemical stability. Teflon® also belongs to this category of substances.

Bastian continues: “When combining the chemical properties of fluoropolymers with the roughness of the lotus plant, surfaces are obtained, from which both water and oil droplets will roll off,”

The researchers say they have already succeeded in producing super-repellent surfaces combining the two approaches, although the surfaces are sensitive to abrasion.

Bastian's answer is to develop a new class of fluorinated polymers, which still allow water and oil to roll off, but are more robust. These polymers - named Fluoropore - possess what the researchers call the 'lotus 2.0 effect' on nearly any surface.

The industrial applications of Fluoropore are also of interest to process engineers . The coating has fine-pore screens, whose chemistry and structure allow for the separation of oil and water mixtures used as cooling lubricants in processing industry.

Excellent work from some of our European colleagues.