Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review

Abstract

The methods and mechanisms of nonsolvent induced phase separation have been studied for more than fifty years. Today, phase inversion membranes are widely used in numerous chemical industries, biotechnology, and environmental separation processes. The body of knowledge has grown exponentially in the past fifty years, which suggests the need for a critical review of the literature. Here we present a review of nonsolvent induced phase separation membrane preparation and characterization for many commonly used membrane polymers. The key factors in membrane preparation discussed include the solvent type, polymer type and concentration, nonsolvent system type and composition, additives to the polymer solution, and film casting conditions. A brief introduction to membrane characterization is also given, which includes membrane porosity and pore size distribution characterization, membrane physical and chemical properties characterization, and thermodynamic and kinetic evaluation of the phase inversion process. One aim of this review is to lay out the basics for selecting polymer-solvent-nonsolvent systems with appropriate film casting conditions to produce membranes with the desired performance, morphology, and stability, and to choose the proper way to characterize these properties of nonsolvent induced phase inversion membranes.

Comparison between hydrophilic and hydrophobic metal nanoparticles on the phase separation phenomena during formation of asymmetric polyethersulphone membranes

“…(1) where W W and W D are the weights of membrane in swollen and dry states, respectively. ρ W denotes the density of pure water at operating conditions (g/cm 3 ) and ρ p represents the density of the polymer (g/cm 3 ). The overall porosity value was obtained as the average of five different samples of each membrane.…”

“…However, besides thermodynamics, the kinetics factors (such as diffusion rate) also play an important role in the morphology development. When the polymer solution (or dope solution) is immersed in a non-solvent bath (or coagulation bath), polymer is solidified through the exchange between the solvent and non-solvent [3]. In their studies, Reuvers et al predicted two types of demixing in a membrane forming-system using the Flory-Huggins theory with binary data on thermodynamics and on the diffusional behaviour of the components present in the system: delayed and instantaneous demixing [4,5].…”

“…Different authors demonstrated that the formation of porous substructures with open and large channellike cavities (called macrovoids) is related to the mechanism of instantaneous demixing [6][7][8]. In the same way, slow precipitation rates (delayed demixing) produce sponge-like structures [3,9]. For these reasons, the choice of solvent/non-solvent system (related to their miscibility), the composition of polymer solution, the composition of the coagulation bath and the casting conditions are key factors during membrane preparation process [10].…”

Improved Permeate Flux of PVDF Ultrafiltration Membrane Containing PVDF-g-PHEA Synthesized via ATRP

“…Table 1 shows chemical compositions for different four types of membranes. In order to prepare for PVDF membranes containing PVDF-g-PHEA via non-solvent induced phase separation (NIPS) [16], PVDF was dissolved in DMSO with the graft copolymer additive in vials at 80 °C for 24 h. To fabricate PVDF pristine membranes, PVDF was dissolved in DMSO in vials at 80 °C for 24 h. Pore size of the membranes was controlled by PVDF content for more accurate flux performance according to the experiment studied by Woo et al [17]. The solutions were cast on nonwoven fabric and then immersed into the water bath.…”

A Highly Structured 1,10-Phenanthroline Arrayed Hydrophobic Sulfone Membrane Platform for the Rapid Determination and Speciation of Fe2+/Fe3+ Ions in Water

“…11 By varying the polymer/solvent ratio and the composition of non-solvent bath, the characteristics of polymeric membranes prepared via non-solvent induced phase separation (NIPS) can be altered. 12 Hence, the present study is focussed on: a) developing a simple and highly-structured 1,10-phenanthroline arrayed PES membrane sensor for direct determination and chemical speciation of Fe 2+ /Fe 3+ in water; b) comparing the influence of the surface hydrophobicity on the assay sensitivity; c) studying the robustness, stability as well as the analytical utility of the developed sensor platform in real sample analysis and finally; d) application of the proposed PES membranebased sensor for the speciation of Fe 2+ /Fe 3+ ions in real water samples.…”