Enhancing the interfacial stability and solvent-resistant property of PDMS/PES composite membrane by introducing a bifunctional aminosilane

The interfacial stability between polydimethylsiloxane (PDMS) active layer and poly(ether sulfone) (PES) support layer was significantly improved by introducing a bifunctional aminosilane, γ-aminopropyltrimethoxysilane (APTMS). APTMS performed not only as a cross-linking agent for PDMS chains but also as a “sticker” anchoring PDMS to the PES support layer. Moreover, the addition of APTMS increased the hydrophilicity of PDMS active layer, leading to a stronger binding between the active layer and the support layer. Energy dispersing spectroscopy (EDS) was used to detect the chemical structure of the PDMS–APTMS/PES composite membrane and molecular dynamics simulation was employed to analyze the interfacial interaction. Positron annihilation lifetime spectroscopy (PALS) was used to correlate the permeation flux with apparent fractional free volume. The swelling behavior and stability of PDMS/PES composite membranes, the effect of APTMS content on the pervaporative desulfurization performance were investigated using n-octane/thiophene mixture as model gasoline system. It was found that incorporation of APTMS endowed the membranes with remarkably enhanced swelling resistance and long-term stability. The PDMS–APTMS-0.06/PES membrane with an APTMS/PDMS weight ratio of 0.06 exhibited the highest permeation flux of 6.95 kg/(m2 h) with an enrichment factor of 3.15 for a feed concentration of 1300 ppmw thiopehene at 306 K.