Triblock Polymer Engineering Enables Hydration‐Rich, High‐Performance, Fouling‐Resistant Interfaces

ABSTRACT Treatment of oily wastewater generated from industrial and human activities (particularly oil recovery processes) remains a long‐standing global challenge. Oily residues (e.g., emulsified oil and fine solids) in the wastewater readily foul and block water‐treatment equipment and downstream units, thereby reducing treatment efficiency and increasing operational and maintenance costs. Here, we report a molecularly engineered triblock polymer (denoted as PHZ) that markedly suppresses oil fouling under different conditions. PHZ comprises cationic, hydrophobic, and zwitterionic blocks, which enable its rapid adsorption onto diverse substrates and foulants, followed by reorganization into a hydration‐rich interfacial layer. Upon adsorption, PHZ molecules reduce the interfacial water contact angle from ≈110° to ≈20° and generate strong steric repulsion between foulants and substrates, providing both energy and physical barriers to mitigate fouling. The resulting PHZ layer prevents direct contact between foulants and target substrates, achieving ≈49% reduction in oil fouling even at an ultralow dosage (e.g., 20 ppm) and outperforming leading commercial antifouling reagents. The combined rapid adsorption, robust interfacial hydration, strong suppression of hydrophobic attractions, and generation of steric repulsions establish a mechanistic basis for PHZ as an efficient fouling‐resistant additive and provide design principles for next‐generation chemicals and materials for diverse industrial water treatment processes.