Engineering Tunable Biomimetic Superhydrophobic Surfaces from Natural Spiky Pollen

Abstract

Superhydrophobic surfaces are essential to a wide range of applications from self-cleaning and anti-icing surfaces on aircraft to antifouling coatings on maritime vessels. However, most artificial superhydrophobic surface designs rely heavily on fluorinated materials, raising serious environmental concerns due to their bioaccumulation and potential carcinogenicity. Natural spiky pollen, an underutilized biowaste, offers a promising alternative to fluorine-based approaches. These particles intrinsically possess a distinctive topography that closely mirrors the hierarchical superhydrophobic micro/nanostructures. Notably, their distinctive geometrical features can further influence and modulate surface wetting behavior. Here, we demonstrate the engineering of superhydrophobic surfaces using spiky pollen from diverse plant species (ragweed, two chrysanthemum subspecies, and sunflower) to investigate the influence of geometrical features on the superhydrophobic performance and to benchmark their effectiveness against fluorinated-modified counterparts. The engineered pollen-based superhydrophobic surfaces demonstrate exceptional water contact angles and tunable wetting states, ranging from Cassie-impregnating states (“petal effect”) for shorter spike lengths to Cassie−Baxter states (“lotus effect”) for longer spikes. This work establishes a sustainable and facile strategy for engineering advanced superhydrophobic surfaces using natural microarchitectures.