Ultrastable Hydrophilic <scp>PTFE</scp> Membranes via <scp>PFAS</scp> ‐Free <scp>EVOH</scp> ‐ <scp> SiO ₂ </scp> ‐Surfactant Interfacial Co‐Assembly

ABSTRACT A fluorine‐free hydrophilic coating was fabricated on polytetrafluoroethylene (PTFE) membranes using sodium dodecylbenzenesulfonate (SDBS), nano‐silica (SiO 2 ), and ethylene‐vinyl alcohol copolymer (EVOH) through a simple immersion–drying process. The modification aimed to improve membrane wettability, permeability, and chemical stability. FTIR, XPS, SEM, and AFM analyses confirmed the formation of a uniform organic–inorganic composite coating. AFM further showed that the characteristic granular morphology and surface roughness changed little after immersion in acidic, alkaline, and oxidative solutions, indicating good nanoscale structural stability under harsh conditions. At the optimal composition (SDBS:SiO 2 :EVOH = 2:1:1), the water contact angle decreased from 124.8° for pristine PTFE to 60.6°, while the pure water flux reached 3727.99 L m −2 h −1 . The modified membrane also exhibited high flux recovery after bovine serum albumin fouling, with a flux recovery ratio of 92.3%. In oil–water separation tests, the membrane achieved separation efficiencies above 98% and maintained stable performance during three consecutive filtration cycles. In addition, stable wettability and permeation performance were retained after 1‐week immersion in solutions ranging from pH 1–14. The results indicate that the EVOH‐stabilized SiO 2 /SDBS coating provides an effective, PFAS‐free, and scalable strategy for preparing durable hydrophilic PTFE membranes under harsh operating conditions.