Preparation of bi-continuous Nylon-66 porous membranes by coagulation of incipient dopes in soft non-solvent baths

► A new type of quaternary system for preparing Nylon-66 membranes is explored. ► It is composed of H2O/1-butanol/formic acid/Nylon-66. ► The strong nonsolvent (H2O) acts as a nucleation agent for forming incipient dopes. ► The soft nonsolvent (1-butanol) serves as a bath to hamper liquid-liquid demixing. ► Skinless bi-continuous structure can be made relatively easily via this system.