Regulating solvent activation by the mechanical force for the fabrication of reverse osmosis membranes with high permeability and selectivity

Solvent activation before heat treatment is an effective way to fabricate a more permeable polyamide (PA) reverse osmosis (RO) membrane. However, this method usually induces a decrease in selectivity due to the excessive swelling and dissolution of PA. A facile strategy of regulating solvent activation by the mechanical force was proposed in this work. With this strategy, the mechanical force was applied to the partial region of membrane surface before solvent activation to strengthen the interactions between the PA fragments and the PA, which would reduce the dissolution of partial PA fragments and alleviate the swelling of PA during activation for higher selectivity; while the region of membrane surface without applying mechanical force would be activated by solvent normally for high permeability. The desalination performances of the RO membranes for both brackish water and seawater were evaluated. The results verified that the membrane prepared by regulating solvent activation had a higher rejection and a comparative flux compared to the membrane activated by solvent directly. This work provides a facile way to fabricate the advanced RO membrane by regulating solvent activation.