Bio-inspired robust superhydrophilic/air-superoleophobic WPU/F-BN@SiO2 composite coating with excellent anti-waxing performance

Abstract

Bioinspired underwater superhydrophilic/superoleophobic coatings with anti-waxing adhesion properties have aroused extensive attention in crude oil production and pipeline transportation, but their practical applications are limited by oil contamination in harsh environments. Herein, a superhydrophilic/air-superoleophobic coating with coral-like porous structures was successfully fabricated via a one-step spraying method by integrating waterborne polyurethane (WPU) and the micro-nano composite particles (F-BN@SiO₂), which were synthesized through in-situ growth of SiO₂ on the boron nitride (BN) surface and subsequent chemical modification with FS-50. The prepared coating exhibited excellent superhydrophilicity/superoleophobicity in both air and water environments (OCA = 152.7 ± 1.3° and WCA = 0°). Compared with the unmodified WPU coating, the wax adhesion force of the WPU/F-BN@SiO₂ coating decreased from 9.954 N to 0.785 N, as the synergistic effect of hierarchical rough structures and low-surface-energy groups enables the coating to form an air film, which weakens van der Waals forces and enhances the repulsion of fluorinated groups, thereby repelling wax crystals into larger aggregates. Moreover, the underwater wax inhibition efficiency of the prepared coating can reach up to 99.86 % due to the rapid formation of hydrated layer to prevent wax crystal aggregation and adhesion. Furthermore, the prepared coating also demonstrated outstanding mechanical and chemical stability even after undergoing 300 cycles of sandpaper abrasion and 3 h immersion in corrosive solutions, which is enabled by the interfacial bonding formed through dopamine self-polymerization between the WPU and composite particles. Therefore, this durable superhydrophilic/air-superoleophobic coating with excellent adaptability to multiple working conditions possesses great application potential in the field of oilfield anti-waxing.