Thin-film composite membranes synthesized by multi-step coating methods

A method for synthesizing a thin-film composite membrane, the method comprising a first cycle of (a), (b), (c), (d), and (e):

• (a) providing an ultrafiltration porous support membrane having an outer surface coated with a thin film and synthesized through interfacial polymerization or interfacial initiation of polymerization;
• (b) contacting the ultrafiltration porous support membrane with a first solution comprising a first monomer, and allowing the first solution to impregnate inside the thin film of the ultrafiltration porous support membrane;
• (c) discarding the first solution;
• (d) contacting the ultrafiltration porous support membrane with a second solution comprising a second monomer, and allowing the second solution to impregnate inside the thin film, whereby the second monomer reacts with the first monomer and optionally with reactive groups of the thin film;
• and
• (e) discarding the second solution, and
• repeating at least one additional cycle of (b), (c), (d), and (e),
• wherein in the at least one additional cycle of (b), (c), (d), and (e), monomer order of the first monomer and the second monomer in (b) and (d) is switched.