In situ mussel-inspired Janus membranes using catechol and polyethyleneimine as the additives for highly efficient oil/water emulsions separation

Janus membranes (JMs) with asymmetrical wettability have been fabricated by (co)deposition of dopamine and its catechol derivatives on the hydrophobic substrates for oil/water emulsions separation, while it remains to be desired to simplify the preparation processes. Here, poly(vinylidene fluoride) membranes using catechol and polyethyleneimine as the additives were fabricated by non-solvent phase inversion on the non-woven fabric. Hydrophilic polycatechol and polyethyleneimine (PCCh-PEI) aggregates migrated on the top side of the fabricated membranes, improving their hydrophilicity. Furthermore, the hydrophobic back surface with irregular nano/micropores and lots of PVDF spherulites was gained after peeling off the supporting fabric. As a result, the as-prepared Janus membranes showed excellent emulsion separation, stability, and durability, which can potentially be used for unidirectional liquid collection with lossless transportation. This work opens a new and facile way for the fabrication of JMs with asymmetric wettability toward the versatile separation of oil/water emulsions. ABSTRACT Janus membranes (JMs) with asymmetrical wettability have been fabricated by (co)deposition of dopamine and its catechol derivatives on the hydrophobic substrates for oil/water emulsions separation, while it remains to be desired to simplify the preparation processes. Here, poly(vinylidene fluoride) membranes using catechol and polyethyleneimine as the additives were fabricated by non-solvent phase inversion on the non-woven fabric. Hydrophilic polycatechol and polyethyleneimine (PCCh-PEI) aggregates migrated on the top side of the fabricated membranes, improving their hydrophilicity. Furthermore, the hydrophobic back surface with irregular nano/micropores and lots of PVDF spherulites was gained after peeling off the supporting fabric. As a result, the as-prepared Janus membranes showed excellent emulsion separation, stability, and durability, which can potentially be used for unidirectional liquid collection with lossless transportation. This work opens a new and facile way for the fabrication of JMs with asymmetric wettability toward the versatile separation of oil/water emulsions.

Automated summary

Janus membranes with asymmetrical wettability have been successfully prepared by depositing dopamine and its derivatives on hydrophobic substrates, along with poly(vinylidene fluoride) membranes using catechol and polyethyleneimine as additives. These membranes exhibit excellent emulsion separation, stability, and durability, offering potential applications in lossless transportation of liquids.