Molecularly Stabilized Porous Membranes with Permanent Hydrophilicity for Durable Sterile Filtration

Conventional porous microfiltration membranes suffer from poor performance recyclability during repeated steam sterilization and inferior antifouling performance, severely limiting their long-term reusability in biopharmaceutical sterile filtration. Herein, we report a high-performance recyclable porous membrane fabricated via vapor-induced phase separation (VIPS) using thermal rigidity free of intrinsic sub- T g β-relaxation and inherent permanent hydrophilic poly (oxindole biphenylene) (POBP). The unique sub- T g -free characteristic eliminates microscale segmental relaxation of polymer chains under high-temperature steam sterilization, endowing the membrane with exceptional morphology structural stability and effective resistance against irreversible pore collapse. Impressively, the optimized membrane maintains a high flux recovery ratio (FRR) of 88.2% after multiple sterilization cycles, realizing outstanding reusable sterilization performance that is unattainable for conventional PES membranes. Meanwhile, the abundant intrinsic oxindole groups endow the membrane with stable permanent hydrophilicity without any secondary modification, completely avoiding the compatibility defects of exogenous hydrophilic additives. This intrinsic hydrophilic surface effectively restrains nonspecific bovine serum albumin (BSA) adsorption and biofouling, achieving nearly full flux recovery after simple water rinsing and excellent antifouling durability.