Polyelectrolyte multilayers having salt-controlled internal structures

An article made by a method comprising:

• contacting a substrate with a first solution comprising first polyelectrolyte chains to form a layer of the first polyelectrolyte on the substrate;
• wherein the first polyelectrolyte comprises a polyanion or polycation chain;
• and
• contacting the layer of the first polyelectrolyte with a second solution comprising second polyelectrolyte chains to form a layer of the second polyelectrolyte on the layer of the first polyelectrolyte;
• wherein the second polyelectrolyte comprises a polyanion or polycation chain of a charge opposite to that of the first polyelectrolyte;
• wherein the first solution or the second solution is an aggregate-forming solution comprising an ionic species having at least two discrete sites of a charge opposite to that of the polyelectrolyte chains in the aggregate-forming solution;
• and
• wherein the ionic species forms, via bridging interactions, aggregates of the polyelectrolyte chains that remain intact in the aggregate-forming solution during the contact.