Regulated SMA Aggregation in PVDF Membranes via Dual Coagulation for Enhanced Protein Binding Efficiency

To address the high costs associated with protein purification in therapeutic applications, we have developed a cost-effective method for fabricating Polyvinylidene Fluoride (PVDF)/styrene-co-maleic anhydride (SMA) membrane absorbers. These mixed matrix membranes were prepared via a two-step coagulation process using the nonsolvent-induced phase separation (NIPS) method. By adjusting the proportions of different components in the first coagulation bath, we optimized the membrane structure and the size of SMA aggregates to enhance protein adsorption. The resulting membranes exhibited a porous surface and sponge-like internal structure, facilitating protein solution inflow and reducing internal resistance. The specific surface area of the PVDF/SMA membrane reached a maximum of 19.2 m²/g, and reducing the SMA aggregate size from 872 nm to 22 nm significantly increased protein adsorption capacity of the membrane from 123.59 mg/ml to 311.26 mg/ml. FTIR and XPS analyses confirmed the successful incorporation of SMA into the membrane, and the membrane demonstrated a high water flux of 6426 L/m²h at 1 bar.