Morphology evolution of thickness-gradient membranes prepared by wet phase-inversion process

Deduction of Surfactants Effect on Performance, Morphology, Thermal and Molecular Properties of Polymeric Polyvinylidene Fluoride (PVDF) Based Ultrafiltration Membrane

“…The preparation of asymmetric membrane structure commonly produced via phase inversion technique [3,4]. This technique is responsible to form typical asymmetric character, which involving skin (upper) and support (bottom) layer with a dense spongy structure occupied beneath the skin layer [5].…”

Morphology transition of asymmetric polyetherimide flat sheet membranes with different thickness by wet phase-inversion process

“…The flat sheet membranes are cast on glass plates, they are then immersed in a water bath at 25 • C. But the flat sheet membranes with different thickness are cast with a special casting knife. At one end of the casting knife, there is a copper wire but nothing at the other end [18]. The flat sheet membranes with different thickness are fabricated by adjusting the copper wire diameter.…”

“…The thickness dependence of macrovoids has been investigated recently [16][17][18][19][20]. Vogrin et al [16] firstly studied membrane morphologies at different membrane thickness with a ternary cellulose acetate/acetone/water system, and investigated that macrovoids appeared at the thickness of 500 m, but disappeared at thicknesses of 150 and 300 m for a 12.5 wt% casting solution.…”

“…Li et al [17] investigated the thickness of sponge-like portions at different entire membranes with polyethersulfone (PES) and copolyimide P84, and firstly observed that there existed a critical structure-transition thickness Lc, which described the transition of membrane morphology from sponge-like to finger-like structure. Zhou et al [18] firstly proposed the concept of "thickness-gradient membrane" and investigated that the morphology evolution of thickness-gradient membranes was controlled by three different membrane thickness regions. Meanwhile, the general sponge-like structure thickness (Lgs) defined as the thickness of sponge-like structure underneath the membrane surface was observed to be a constant.…”

Improved microfiltration and bacteria removal performance of polyethersulfone membranes prepared by modified vapor‐induced phase separation

“…[1][2][3][4] This process is characterized by rapid exchange of solvent / non-solvent and, typically, the formation of asymmetric membranes with a dense skin layer. [5][6][7] In recent years, the non-solvent vapor-induced phase separation (VIPS), as a newly developed form of NIPS process, has attracted great research interest. In this process, the cast polymer film is exposed to nonsolvent vapor before immersion in the coagulation bath.…”