Is the solvent activation strategy before heat treatment applicable to all reverse osmosis membranes?

In our previous work, it has been proved that regulated solvent activation by mechanical force before heat-treatment was an effective strategy to prepare high-permselectivity polyamide (PA) reverse osmosis (RO) membrane. However, the universality of the regulated solvent activation for the membranes prepared with different interfacial polymerization (IP) processes has not been explored. The influence of mechanical force-regulated solvent activation on structure and performance of RO membranes prepared with different additives was analyzed systematically in this work. Dimethyl carbonate (DMC) as an organic co-solvent which could produce a thicker and looser PA skin layer and 1-methylimidazole (1-MI) as an aqueous additive which could produce a denser and thinner PA skin layer were used to change the IP processes, respectively. When DMC was added to modify IP, the mechanical force-regulated solvent activation improved the rejection of DMC-modified membrane effectively while maintaining the excellent flux. It was concluded that mechanical force-regulated solvent activation was suitable for the co-solvent-optimized IP process. But the mechanical force-regulated solvent activation had no significant influence on structure and performance of 1-MI-modified membrane, which may be due to the high compactness of the PA skin layer prepared with 1-MI. This work provides the insight of the applicability of the regulated solvent activation for different membrane structures.