Robust superhydrophilic polydopamine-assisted zwitterionic/silica hybrid coatings on polypropylene for antifogging and anti-icing

Polypropylene (PP) is widely used in transparent packaging, optical components, and functional membranes; however, its intrinsic hydrophobicity and poor interfacial adhesion severely restrict the construction of durable superhydrophilic surfaces. To overcome these limitations while preserving the excellent bulk properties of PP, a durable and scalable superhydrophilic coating was fabricated by introducing a mussel-inspired polydopamine (PDA) adhesive interlayer, followed by the deposition of an organic–inorganic hybrid coating composed of zwitterionic poly(carboxybetaine acrylamide) (PCBAA) and silica sol. The PDA interlayer provides robust interfacial adhesion between the coating and PP substrate, while zwitterionic PCBAA introduces abundant hydration sites to enhance surface hydrophilicity and silica nanoparticles reinforce the hybrid network structure. FTIR and XPS analysis confirmed the successful synthesis of CBAA and the successful immobilization of the hybrid coating on the PP surface. The coating with a CBAA/silica sol mass ratio of 1:2 exhibited the best overall performance, achieving a water contact angle of approximately 5°, excellent antifogging capability, and high optical transparency. At −15 °C, the coating exhibited a freezing time of 603 s, corresponding to a freezing delay of 425 s relative to pristine PP. Moreover, the optimized coating maintained stable superhydrophilicity after hot-water treatment and immersion under acidic and neutral conditions, while retaining good hydrophilicity after repeated sandpaper abrasion. These results demonstrate that the PDA-PCBAA/SiO₂ hybrid coating provides a simple and effective strategy for fabricating multifunctional superhydrophilic PP surfaces with excellent antifogging, anti-icing, and durability.