Bio-inspired Superhydrophilic Coatings with High Anti-Adhesion Against Mineral Scales

The unexpected adhesion of certain inorganic minerals on solid surfaces is constantly a source of severe problems in daily life and industrial production, including scales in water pipes. Inspired by the nanostructured inner surface of normal renal tubules, we design a superhydrophilic nanohair coating composed of a poly(hydroxyethyl methacrylate) (PHEMA) hydrogel, which shows high anti-adhesion against mineral scales under flow conditions. Even at a high temperature of 80° C, the nanohair hydrogel coatings still show excellent anti-scaling performance compared to a flat hydrogel coating and a commercial water pipe with a polyvinylchloride (PVC) surface. The anti-scaling experiments and theory simulation reveal the crucial role of superhydrophilicity and fluid-assisted motion of the nanohairs in the anti-adhesion property. This study may provide promising insight into the design of high anti-adhesion coatings for resisting mineral scale attachment in water management systems. Mineral microcrystals that form inside water pipes and cooling towers can now be repelled using hydrogels with bio-inspired shapes. To prevent buildup of calcium-based kidney stones, the human kidney has renal tubules with thin, hair-like morphologies. Jingxin Meng and Shutao Wang from the Chinese Academy of Sciences and colleagues report that the polymer poly(hydroxyethyl methacrylate) can be formed into similar ‘nanohairs’ by using a combination of photopolymerization and template-assisted growth. Microscopy measurements revealed that when the new coating was exposed to a flow of mineral-saturated water, its strong affinity for aqueous molecules prevented scaling — up to 93% fewer crystals were observed on the nanohair surface compared to a flat hydrogel. These effects could be enhanced by increasing in the nanohair length. The superhydrophilic nature of the material proved resilient to temperatures as high as 80 degrees Celsius. Inspired by the anti-stone phenomenon of normal renal tubule, we report that superhydrophilic nanohair hydrogel coating shows high anti-adhesion against mineral scales under flowing conditions. The experiment and theory simulation reveal the crucial role of superhydrophilicity and fluid-assisted motion of nanohair in the anti-scale property. Even at a high temperature of 80 °C, it still shows high anti-scale performance, which is much better than the flat hydrogel coating and commercial water pipe with polyvinylchloride surface. This study may provide a promising clue to design high anti-adhesion coatings for resisting mineral scales attachment in water management systems.