Hierarchically textured superhydrophobic polyvinylidene fluoride membrane fabricated via nanocasting for enhanced membrane distillation performance

The further advance of membrane distillation (MD) is hampered due to inadequate membrane durability challenged by wetting-induced performance deterioration. The current study presents a novel approach to fabrication of superhydrophobic polyvinylidene fluoride (PVDF) membranes via construction of hierarchical textures on membrane surfaces based on a nanocasting strategy. Two types of PVDF membranes with different surface textures were prepared, separately using a stainless-steel mesh (SSM) or its negative polydimethylsiloxane (PDMS) template as a fabrication substrate. The obtained membranes were systematically characterized in terms of membrane morphology, wetting behavior, MD performance, and antifouling performance. Consequently, the PDMS-based membrane obtained a plaited surface texture, resulting in a high static contact angle of similar to 153 degrees and a high sliding angle of > 90 degrees. The resultant parahydrophobic membrane surface resembled a petal surface. The SSM-based membrane obtained a wave-like pattern, resulting in a high static contact angle of similar to 164 degrees and a low sliding angle of similar to 6.8 degrees. The resultant superhydrophobic membrane surface resembled a lotus leave surface. Moreover, both membranes achieved higher water flux and enhanced antifouling performance with no significant compromise in salt rejection. Particularly, the SSM-based membrane achieved the highest flux and best antifouling performance, suggesting promising applications in various fields.