Membrane formation by immersion precipitation: The role of a polymeric additive

In this thesis the immersion precipitation process is studied for systems in which two polymers are present. In its basic form, immersion precipitation is carried out by immersing a thin film of a concentrated polymer solution into a bath of nonsolvent. By exchange of solvent from the polymer solution, and nonsolvent from the coagulation bath, the polymer solution becomes instable. Liquid-liquid phase separation results in a polymer lean phase and a polymer rich phase. The polymer lean phase forms pores inside a matrix created by the polymer rich phase, which forms the membrane. The objective of this thesis is to investigate the effects of the addition of a second polymer into the polymer solution. The use of a second polymer (polymeric additive) that is miscible with the nonsolvent can result in more open porous (co-continuous) structures and a better defined porosity.