Abstract:
Traditional phase inversion process mainly involves the pore structure regulation of polymeric membranes via controlling the kinetics and thermodynamics, which is a typical physical process, rarely regulating membrane surface/interface properties. However, the surface/interface properties, such as anti-fouling, anti-bacterial and non-clotting performances, influence the separation performances substantially. We propose a “chemical phase inversion” in this paper, which endows the membrane with specific chemical functional surfaces/interfaces during phase inversion process. The key point is to manipulate the migrating route and fixing configuration of funcntional molecules during phase inversion process to accomplish the surface/interface functionalization of polymeric membranes. We summarize the surface/interface functionalization strategies through “chemical phase inversion”, which can be classfied into, the inside-out migration and
in-
situ cross-linking functionalization strategy based on casting solution, the outside-in migration and off-site cross-linking functionalization strategy based on coagulation bath, and the top-down migration and interfacial cross-linking functionalization strategy based on microporous membranes. According to the differences of the modifiers and the post-treatment process, the membrane can be endowed with excellent anti-fouling, anti-bacterial and non-clotting performances, respectively. The strategies are utilized to modify the microporous membranes for water treatment, oil/water separation and hemodialysis etc. Therefore, the theory of “chemical phase inversion” provides a new research idea for the preparation and separation of high-performance and multifunctional polymeric microporous membranes. However, the introduction of modifiers will also have an impact on phase inversion process, thereby affecting membrane microporous structures. We will further improve the “chemical phase inversion” theory from the view of microporous structure regulation and surface functionalization in later researches.