Fluorine-free superhydrophobic coatings with bird's nest architecture for high-strength and mechanically durable paper

Superhydrophobic paper exhibits vast potential for everyday use, artistic creation, and cultural conservation, however, the difficulty of synergistically balancing the simplicity, transparency, mechanical weakness, and green durability restricts its application. Inspired by the “bird's nest” structure and its water-repellent nature, hydrophobically modified cellulose nanofibers (MCNFs) and beeswax (BW) were sequentially sprayed onto polydimethylsiloxane-precoated Xuan paper to serve respectively as the “twig” skeleton and “mud” binder, thereby establishing transparent superhydrophobic coating, together with good mechanical durability, improved tensile strength, folding endurance, and resistance to acid and alkali, as well as anti-fouling, self-cleaning, and resistance to aging and UV aging. Especially when the contents of MCNFs and BW are 0.05 g and 0.5 g, the coating exhibits optimal multi-functional properties. With less MCNFs, more pores are filled by BW to form a dense coating that prevents corrosion and enhances stress transfer and energy dissipation. Through a balanced integration of simplicity, greenness, high-strength, and multi-functionality, this strategy creates water-repellent paper that is well-adapted to delicate paper-based applications.