| Physicists at the Laboratoire de Physique des Solides (CNRS/Université Paris-Saclay) have developed innovative textured surfaces capable of reducing foam friction without the need for any external lubricating agent. Unlike conventional surfaces that require an oily coating, these new surfaces make direct use of the liquid contained in the foam to self-lubricate, leading to a friction reduction of up to 30%. |
Liquid foams are widely used in industries such as food processing, cosmetics, chemistry, and energy. However, their transport remains a challenge, as they tend to rub against the walls of pipes and channels, slowing down their flow and increasing energy consumption. Understanding and controlling these interactions is therefore crucial for optimizing industrial processes involving foams.
To test their approach, the researchers compared the behavior of foam flowing over a smooth surface and over a self-infused textured surface. The experiments revealed that the foam moved much faster on the textured surface, with friction reduced by up to 30%. This result is promising for many applications, particularly in industries where foam transport is a key issue.
To design these self-lubricating surfaces, the researchers used photolithography techniques to engrave regular patterns on silicone substrates—arrays of 10-micrometer pillars spaced 20 micrometers apart—forming a texture capable of trapping a thin liquid film drawn from the foam itself. This liquid film acts as a local lubricant between the foam and the surface, eliminating the need for any external lubricating layer.
The experiments were carried out using a tilting setup that allowed comparison of foam flow velocities on smooth and textured surfaces. The results clearly showed that the foam slid much faster on the microstructured surface, with a significant reduction in friction.
Published in Physical Review Fluids, this research marks an important step toward understanding the interactions between foams and solid surfaces, and could inspire new strategies for improving the management of industrial foam flows.
Contributors: Soft Matter at Interfaces team (MMOI du LPS)
Funding: ANR ASPERFOAM
Reference: https://doi.org/10.1103/PhysRevFluids.10.L011601
Contact: François Boulogne — francois.boulogne@cnrs.fr