Controlling the Morphology of PVDF Hollow Fiber Membranes by Promotion of Liquid–Liquid Phase Separation

Abstract

In literature, liquid–liquid (L–L) phase separation has been widely adopted as the principle technique by which polymeric membranes are produced. However, the promotion of L–L phase separation as the means of controlling membrane morphology is still debatable. Thus, this work aims to introduce a facile and cost‐effective technique for controlling the morphology of poly(vinylidene fluoride) (PVDF) hollow fiber membranes (HFMs). The proposed technique is based on promotion of L–L phase separation which can be achieved through two different approaches: 1) reducing the distance between locations of dope and binodal curve through locating spinning dope on nonsolvent (water)/solvent (2‐pyrrolidone)/polymer (PVDF) ternary phase diagram by increasing of nonsolvent content and maintaining of polymer concentration at initial level; 2) simultaneous occurrence of thermally and nonsolvent induced phase separation (TNIPS). It is found that L–L phase separation promotion based on the above described approaches yields to PVDF HFM with partially double‐layered structure, enhanced mechanical properties, higher porosity, and smaller average pore radius with the potential to purify textile wastewater containing C.I. Disperse Violet 33. The proposed technique is advantageous due to lack of need for additives or post‐treatment process for HFM synthesis.

Effects of coating technique on the physicochemical properties and structure of MoS2‐TiO2/PVDF‐PES for membrane distillation application

“…This discrepancy in porosity reduction between the two methods is attributed to the layering method's tendency to deposit concentrated particles, leading to pore blockage as compared to the interlinking method 29 . However, the porosity of membranes prepared in this work was lower than the typical porosity range of PVDF membranes, which commonly falls between 70% and 8 0% 30‐32 …”

“…29 However, the porosity of membranes pre- pared in this work was lower than the typical porosity range of PVDF membranes, which commonly falls between 70% and 8 0%. [30][31][32] The wettability of coated PVDF-based hollow fiber membranes developed in this work was determined based on WCA analysis (Fig. 5).…”

One-Step Fast Fabrication of Electrospun Fiber Membranes for Efficient Particulate Matter Removal

“…Compared with other fiber fabrication techniques, including self-assembly [ 28 ], the template method [ 29 ], and phase separation [ 30 ], electrospinning is simple and versatile [ 31 ]. In principle, electrospinning involves the use of high-voltage electrostatic force to generate a polymer melt or solution jet [ 32 ].…”

Continuous and Controllable Preparation of Sodium Alginate Hydrogel Tubes Guided by the Soft Cap Inspired by the Apical Growth of the Plant

“…Because of their potential applications, hydrogel tubes and the way they can be fabricated have been investigated by many groups. So far, the reported preparation methods could be summarized as mold manufacturing, , phase separation, , self-folding, − gas foaming, , 3D printing, − extrusion molding, , and microfluidic technology. − The mold manufacturing method was to inject the prepolymer solution into the glass mold or sacrificing cylinder to form hydrogel tubes by thermal heating, UV irradiation, or ion cross-linking. The size or shape of the tubes depended on the preprepared mold.…”