APTES-mediated interfacial coupling enables efficient ion sieving and antifouling performance in nanofiltration membranes

APTES/cGO coupling increased the PVDF β-phase fraction to 80%. • The tailored support yielded a smooth PA layer only ~40.9 nm thick. • Permeance reached 15.5 L m⁻² h⁻¹ bar⁻¹ with 98.6% Na₂SO₄ rejection. • NaCl rejection reached 60.5%, and flux recovery reached 90.2%. • Hydration dominated fouling resistance; polarization may assist cleaning. To transcend the long-standing trade-off between permeability, selectivity, and antifouling performance in nanofiltration membranes, we proposed a crystallization-guided interfacial coupling strategy employing 3-aminopropyltriethoxysilane (APTES) to construct a covalently integrated interface between carboxylated graphene oxide (cGO) and β-phase polyvinylidene fluoride (PVDF) for a PIP/TMC-based polyamide selective layer. This dual-function modification induced the directional crystallization of the electroactive β-phase while chemically anchoring cGO within the polymer matrix, thereby reinforcing structural integrity and enabling precise control over ion transport pathways. The resulting APTES-coupled cGO–PVDF membrane achieved a high rejection of 98% for Na₂SO₄ and 60% for NaCl, with a water permeance of 15.5 L·m⁻²·h⁻¹ ·bar⁻¹ under 5 bar operation. After simple water rinsing, the membrane recovered 90.2% of its initial flux. Molecular simulations and experimental evidences revealed that interfacial charge redistribution facilitated by APTES could enhance Donnan exclusion and ion sieving, while the synergistic interplay between the piezoelectric β-phase and localized cation polarization dynamically could suppress fouling. Together, these features defined a unified charge–structure–response paradigm that underpinned a new class of high-performance nanofiltration membranes with self-adaptive, multifunctional separation capabilities. Download: Download high-res image (339KB) Download: Download full-size image