Extreme Wetting-Resistant Multiscale Nano-Microstructured Surfaces for Viscoelastic Liquid Repellence

Abstract EN

We demonstrate exceptional wetting-resistant surfaces capable of repelling low surface tension, non-Newtonian, and highly viscoelastic liquids.

Theoretical analysis and experimental result confirm that a higher level of multiscale roughness topography composed of at least three structural length scales, ranging from nanometer to supermicron sizes, is crucial for the reduction of liquid-solid adhesion hysteresis.

With Cassie-Baxter nonwetting state satisfied at all roughness length scales, the surface has been proven to effectively repel even highly adhesive liquid.

Practically, this high-level hierarchical structure can be achieved through fractal-like structures of silica aggregates induced by siloxane oligomer interparticle bridges.

The induced aggregation and surface functionalization of the silica particles can be performed simultaneously within a single reaction step, by utilizing trifunctional fluoroalkylsilane precursors that largely form a disordered fluoroalkylsiloxane grafting layer under the presence of sufficient native moisture preadsorbed at the silica surface.

Spray-coating deposition of a particle surface layer on a precoated primer layer ensures facile processability and scalability of the fabrication method.

The resulting low-surface-energy multiscale roughness exhibits outstanding liquid repellent properties, generating equivalent lotus effect for highly viscous and adhesive natural latex concentrate, with apparent contact angles greater than 160°, and very small roll-off angles of less than 3°.