Advanced porous polymer membranes from self-assembling block copolymers
AbstractThe development of novel polymer membranes is a fascinating and challenging field in materials science and technology, as both the chemical composition and the processing have a big influence on the final properties of polymer membranes such as surface properties, pore structure and pore functionality. Progress in membrane-based separation processes like water and wastewater treatment, desalination and other separation applications depends on both a better understanding of the influence of the chemical composition of the membrane material and the membrane structure on the separation performance. In this review, first an overview of different types of polymer membranes and the separation mechanisms is given. Then the well-established fabrication of integral asymmetrically structured membranes by phase inversion methods in different geometries is presented before the more challenging combination of nonsolvent induced phase separation (NIPS) with block copolymer self-assembly is discussed. This leads to so-called integral asymmetric isoporous membranes composed of a thin selective surface layer with regular arranged and similar-sized pores on top of a thicker irregular, spongy sublayer. These membranes are the main focus of this review. So far, isoporous block copolymer membranes are still far from large scale production and commercial reality, however, they offer one of the most promising platforms for higher separation performance. They not only have potential in applications such as proteins separation, but can also become useful for the separation of small charged or uncharged molecules after appropriate post-functionalization of the pores.