Porous polyelectrolyte complex films and foams and related methods

A method for making a porous polyelectrolyte complex (PEC) film having a predetermined porosity, the method comprising:

• coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate mixture having a salt concentration;
• exposing the coating to an aqueous medium having another salt concentration, for a time to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout,
• wherein a difference ΔC-M between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film, wherein the porous PEC film is composed of a first sublayer and a second sublayer overlying the first sublayer and at the surface of the porous PEC film, wherein the first and second sublayers are characterized by different average pore diameters.

A method for making a porous polyelectrolyte complex (PEC) film having a predetermined porosity, the method comprising:

• coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate mixture having a salt concentration;
• exposing the coating to an aqueous medium having another salt concentration, for a time to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout,
• wherein a difference ΔC-M between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film, wherein the PE coacervate mixture further comprises a foaming agent and the method further comprises inducing the foaming agent to undergo a reaction to release a gas, thereby generating bubbles throughout the PE coacervate mixture, prior to the exposing step.