Switchable pH-responsive polymeric membranes prepared via block copolymer micelle assembly

A Versatile Assembly Approach toward Multifunctional Supramolecular Poly(Ionic Liquid) Nanoporous Membranes in Water

Hydrogen (H)-bonding-integration of multiple ingredients into supramolecular polyelectrolyte nanoporous membranes in water, thereby achieving tailor-made porous architectures, properties, and functionalities, remains one of the foremost challenges in materials chemistry due to the significantly opposing action of water molecules against H-bonding. Herein, a strategy is described that allows direct fusing of the functional attributes of small additives into water-involved hydrogen bonding assembled supramolecular poly(ionic liquid) (PIL) nanoporous membranes (SPILMs) under ambient conditions. It discloses that the pore size distributions and mechanical properties of SPILMs are rationally controlled by tuning the H-bonding interactions between small additives and homo-PIL. It demonstrates that, benefiting from the synergy of multiple noncovalent interactions, small dye additives/homo-PIL solutions can be utilized as versatile inks for yielding colorful light emitting films with robust underwater adhesion strength, excellent stretchability, and flexibility on diverse substrates, including both hydrophilic and hydrophobic surfaces. This system provides a general platform for integrating the functional attributes of a diverse variety of additives into SPILMs to create multifunctional and programmable materials in water.

Advanced stimuli-responsive membranes for smart separation

Membranes have been extensively studied and applied in various fields owing to their high energy efficiency and small environmental impact. Further conferring membranes with stimuli responsiveness can allow them to dynamically tune their pore structure and/or surface properties for efficient separation performance. This review summarizes and discusses important developments and achievements in stimuli-responsive membranes. The most commonly utilized stimuli, including light, pH, temperature, ions, and electric and magnetic fields, are discussed in detail. Special attention is given to stimuli-responsive control of membrane pore structure (pore size and porosity/connectivity) and surface properties (wettability, surface topology, and surface charge), from the perspective of determining the appropriate membrane properties and microstructures. This review also focuses on strategies to prepare stimuli-responsive membranes, including blending, casting, polymerization, self-assembly, and electrospinning. Smart applications for separations are also reviewed as well as a discussion of remaining challenges and future prospects in this exciting field. This review offers critical insights for the membrane and broader materials science communities regarding the on-demand and dynamic control of membrane structures and properties. We hope that this review will inspire the design of novel stimuli-responsive membranes to promote sustainable development and make progress toward commercialization.

Joining Two Switches in One Nano-Object: Photoacidity and Photoisomerization in Electrostatic Self-Assembly

Multi-switchable supramolecular nano-objects that respond to irradiation of different wavelengths with changes in size and shape have been built from two different water-soluble molecular switches, joined by attachment to the same polyelectrolyte. Accordingly, two wavelength-specific reactions, namely the excited-state proton dissociation of a photoacid and the cis-trans isomerization of an azo dye, are combined in one supramolecular nano-object that is stable in aqueous solution. The concept has potential in the fields of sensors, molecular motors, and transport.

Thermoresponsive Microgel-Based Free-Standing Membranes: Influence of Different Microgel Cross-Linkers on Membrane Function

In this study we show a possibility to produce thermoresponsive, free-standing microgel membranes based on N-isopropylacrylamide (NIPAM) and the UV-sensitive comonomer 2-hydroxy-4-(methacryloyloxy)benzophenone (HMABP). To influence the final network structure and functionality of the membranes, we use different cross-linkers in the microgel syntheses and characterize the resulting structural microgel properties and the swelling behavior by means of AFM, FTIR, and PCS measurements. Varying the cross-linker results in significant changes in the structure and swelling behavior of the individual microgels and has an influence on the incorporation of the comonomer, which is essential for subsequent photochemical membrane formation. We investigate the ion transport through the different membranes by temperature-dependent resistance measurements revealing a sharp increase in resistance when the copolymer microgels reach their collapsed state. The resistance of the membranes can be adjusted by different cross-linkers and the associated incorporation of the comonomer. Furthermore, we show that transferring a reversible cross-linker from a cross-linked state to an un-cross-linked state strongly influences the membrane properties and even reverses the switching behavior, while the mechanical stability of the membrane is maintained.

Iron-containing poly(ionic liquid) membranes: a heterogeneous Fenton reaction and enhanced anti-fouling ability

Iron-containing poly(ionic liquid) membranes were prepared by Cu(0)-mediated reversible deactivation radical polymerization, which was achieved to catalyze a heterogeneous Fenton reaction and realize self-cleaning of the membrane surface.

High-Flux pH-Responsive Ultrafiltration Membrane for Efficient Nanoparticle Fractionation

Fractionation of nanoparticles with different sizes from the mixture by using a single membrane would reduce the membrane cost and enhance the efficiency. In this study, an amphiphilic pH-responsive copolymer was prepared by grafting a pH-responsive hydrophilic polymethacrylic acid (PMAA) side chain from a hydrophobic poly(vinylidene fluoride-co-chlorotrifluoroethylene), P(VDF-CTFE) backbone. Subsequently, the isoporous pH-responsive membranes (PPMs) were prepared from the functional copolymers with different PMAA chain lengths. PPM indicated reversible pore size decreasing with the increasing pH of the feed. Moreover, the membrane pore size variation range was further extended by adjusting the PMAA side chain length of the copolymer to reach a wide range from 10.2 to 34.5 nm. Owning to the amphiphilic nature of the copolymer, PPM showed a narrow pore size distribution which is responsible for the much higher pure water flux of PPM than the conventional UF membrane with similar retention capability. In the fractionation test, the mixed 20 and 30 nm polystyrene nanoparticles were penetrating PPM at pH 11 and 3, respectively. The pH-responsive PPM indicated great potential for nanoparticle fractionation, while the uniform pores of PPM further enhanced the membrane performance in terms of permeability and selectivity.

Current status and future directions of self-assembled block copolymer membranes for molecular separations

One of the most efficient and promising separation alternatives to thermal methods such as distillation is the use of polymeric membranes that separate mixtures based on molecular size or chemical affinity. Self-assembled block copolymer membranes have gained considerable attention within the membrane field due to precise control over nanoscale structure, pore size, and chemical versatility. Despite the rapid progress and excitement, a significant hurdle in using block copolymer membranes for nanometer and sub-nanometer separations such as nanofiltration and reverse osmosis is the lower limit on domain size features. Strategies such as polymer post-functionalization, self-assembly of oligomers, liquid crystals, and random copolymers, or incorporation of artificial/natural channels within block copolymer materials are future directions with the potential to overcome current limitations with respect to separation size.

Asymmetric Solvent-Annealed Triblock Terpolymer Thick Films Topped by a Hexagonal Perforated Lamellar Nanostructure

Asymmetric and nanostructured polystyrene-block-poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO or SVEO, S:V:EO ≈ 56:34:10, 79.5 kg mol^-1 ) thick films blended with 20 wt% of a short PS homopolymer (hPS, 10.5 kg mol^-1 ) are achieved by combining the non-solvent induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. Here, the NIPS step allows for the formation of a highly-permeable sponge-like substructure topped by a dense thin layer exhibiting poorly-ordered nanopores while the subsequent SVA treatment enables to reconstruct the material top surface into a porous monolayer of well-ordered hexagonal perforated lamellae (HPL). This optimized film architecture generated by NIPS-SVA shows a water permeability of 860 L h^-1 m^-2 bar^-1 , which is roughly two times higher than the flux measured through NIPS made PS-b-P2VP-b-PEO/hPS materials having poorly-ordered nanopores. The post-SVA treatment is also revealed as a powerful tool to tailor the thickness of the nanostructure formed within the blended material because monoliths entirely composed of a HPL phase are produced by increasing the time of exposure to a chloroform stream. The water flux of such PS-b-P2VP-b-PEO/hPS monoliths is found to be an order of magnitude lower than that of their asymmetric film homologues.

Preparation of photoactive ZnS-composite porous polymer films: Fluorescent and morphological properties

This work describes the use of the breath figure (BF) method for the fabrication of photoactive porous polymer films and the characterization of their responsive to photo stimulus. The films incorporate self-assembled photoactive polymers and ZnS nanoparticles (NPs). The effect of both components on the optical and morphological properties of the films were analyzed. Films with a hexagonally ordered pattern were obtained. The photoactive polymer was prepared by grafting the photochromic component 1-(2-hydroxyethyl)-3,3-dimethylindoline-6-nitrobenzopyran (SP) to polystyrene-block-polymethacrylic acid (PS-b-PMMA). ZnS NPs were incorporated into the polymer solution, and the films were prepared using spin-coating on glass substrates before subjecting them to the BF method. The hollow footprints were obtained before introducing the ZnS NPs in order to maintain the necessary conditions for hexagonal film growth. Accordingly, the SEM micrographs of the films prepared in the presence of ZnS NPs displayed a loss in the pore arrangement as a consequence of the interaction between SP moiety and NPs. The light-emitting properties of films were characterized by blue and violet colors when exposed to UV light under fluorescence. Progress in the field of breath-figure formation and its application, such as exemplified in this work, leads to functional structures with suitable applications in chemistry and materials science. It is expected that such microstructured polymeric films will have interesting applications in photonic and optoelectronic devices.

Polyelectrolytes as Building Blocks for Next-Generation Membranes with Advanced Functionalities

The global society is in a transition, where dealing with climate change and water scarcity are important challenges. More efficient separations of chemical species are essential to reduce energy consumption and to provide more reliable access to clean water. Here, membranes with advanced functionalities that go beyond standard separation properties can play a key role. This includes relevant functionalities, such as stimuli-responsiveness, fouling control, stability, specific selectivity, sustainability, and antimicrobial activity. Polyelectrolytes and their complexes are an especially promising system to provide advanced membrane functionalities. Here, we have reviewed recent work where advanced membrane properties stem directly from the material properties provided by polyelectrolytes. This work highlights the versatility of polyelectrolyte-based membrane modifications, where polyelectrolytes are not only applied as single layers, including brushes, but also as more complex polyelectrolyte multilayers on both porous membrane supports and dense membranes. Moreover, free-standing membranes can also be produced completely from aqueous polyelectrolyte solutions allowing much more sustainable approaches to membrane fabrication. The Review demonstrates the promise that polyelectrolytes and their complexes hold for next-generation membranes with advanced properties, while it also provides a clear outlook on the future of this promising field.

Downsizing of Block Polymer-Templated Nanopores to One Nanometer via Hyper-Cross-Linking of High χ-Low N Precursors

Synthesizing nanoporous polymer from the block polymer template by selective removal of the sacrificial domain offers straightforward pore size control as a function of the degree of polymerization (N). Downscaling pore size into the microporous regime (<2 nm) has been thermodynamically challenging, because the low N drives the system to disorder and the small-sized pore is prone to collapse. Herein, we report that maximizing cross-linking density of a block polymer precursor with an increased interaction parameter (χ) can help successfully stabilize the structure bearing pore sizes of 1.1 nm. We adopt polymerization-induced microphase separation (PIMS) combined with hyper-cross-linking as a strategy for the preparation of the bicontinuous block polymer precursors with a densely cross-linked framework by copolymerization of vinylbenzyl chloride with divinylbenzene and also Friedel-Crafts alkylation. Incorporating 4-vinylbiphenyl as a higher-χ comonomer to the sacrificial polylactide (PLA) block and optimizing the segregation strength versus cross-linking density allow for further downscaling. Control of pore size by N of PLA is demonstrated in the range of 9.9-1.1 nm. Accessible surface area to fluorescein-tagged dextrans is regulated by the relative size of the pore to the guest, and pore size is controlled. These findings will be useful for designing microporous polymers with tailored pore size for advanced catalytic and separation applications.

Phenylalanine-Tethered pH-Responsive Poly(2-Hydroxyethyl Methacrylate)

A series of pH-responsive random copolymers comprised of 2-hydroxyethyl methacrylate (HEMA) and tert-butyl carbamate (Boc)-protected phenylalanine methacryloyloxyethyl ester (Boc-Phe-EMA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in N,N'-dimethylformamide (DMF) at 70 °C. The synthesized copolymers were comprehensively characterized using a combination of techniques, including ¹ H NMR, FT-IR spectroscopy and size exclusion chromatography (SEC). Reactivity of each monomers towards controlled radical polymerization was evaluated by determining the reactivity ratios by virtue of extended Kelen-Tüdös method at high conversions revealed the higher reactivity of non-modified HEMA (r_HEMA =1.03) in contrast to Boc-Phe-EMA (r_Boc-Phe-EMA =0.48). Furthermore, the expulsion of the Boc-groups resulted copolymers with ionizable pendant primary ammonium and hydroxyl groups. To understand the glass transition behaviours of homo- and co-polymers, differential scanning calorimetric (DSC) measurements were carried out. The effect of HEMA content on the pH-sensitivity of the copolymers in aqueous medium was investigated through turbidity measurements. Finally, the counteranion exchange from trifluoroacetate to chloride provided copolymers with enhanced water solubility and unaltered phase transition pH.

Adsorption of Anionic Dyes Using a Poly(styrene-block-4-vinylpyridine) Block Copolymer Organogel

An organogel was prepared by chemically cross-linking a poly(styrene-block-4-vinylpyridine) diblock copolymer using dibromododecane in dimethylformamide. Analysis of the prominent structure peak in small-angle X-ray scattering along with the results of light scattering and rheological profile suggests the bridging of the spherical micelles to one another to form an interconnected network after gelation. The use of this organogel as a selective adsorbent for removing anionic dyes from individual aqueous dye solutions and in a mixture of cationic and anionic dye solutions has shown more than 90% removal of the anionic dyes within 2 h. The regeneration and reusability studies showed that even after 20 cycles, the adsorption property of the organogel holds extremely well still beyond 90%. These results are indicative of the potential use of poly(styrene-block-4-vinylpyridine) organogel for the anionic ions removal in wastewater treatment.

Stimuli-Responsive Multifunctional Phenylboronic Acid Polymers Via Multicomponent Reactions: From Synthesis to Application

Stimuli-responsive polymers undergo changes under different environmental conditions. Among them, phenylboronic acid (PBA) containing polymers (PBA-polymers) are unique, because they can selectively react with diols to generate borates that are sensitive to pH, sugars, and H₂ O₂ , and can be effectively used to synthesize smart drug carriers and self-healing hydrogels. Recently, multifunctional PBA-polymers (MF-PBA-polymers) have been developed using multicomponent reactions (MCRs) to introduce PBA groups into polymer structures. These MF-PBA-polymers have features similar to those of traditional PBA-polymers; moreover, they exhibit additional properties, such as fluorescence, antimicrobial activity, and antioxidant capability, when different MCRs are used. In this mini review, the preparation of these MF-PBA-polymers are summarized and the new properties/functions that have been introduced into these polymers using different MCRs are discussed. The uses of these MF-PBA-polymers as fluorescent cell anticoagulants, drug carriers, and gelators of functional self-healing hydrogels have been discussed. Additionally, the challenges encountered during their preparation are discussed and also the future developments in this field are touched upon.

Synthesis of hierarchical porous Prussian blue analogues in partially miscible ionic liquid/ethanol solution near the phase boundary

Hierarchical porous PBAs with excellent catalytic performance were controllably synthesized in a partially miscible IL/ethanol system.

Photoresponsive Photoacid-Macroion Nano-Assemblies

In this study, light-responsive nano-assemblies with light-switchable size based on photoacids are presented. Anionic disulfonated napthol derivates and cationic dendrimer macroions are used as building blocks for electrostatic self-assembly. Nanoparticles are already formed under the exclusion of light as a result of electrostatic interactions. Upon photoexcitation, an excited-state dissociation of the photoacidic hydroxyl group takes place, which leads to a more highly charged linker molecule and, subsequently, to a change in size and structure of the nano-assemblies. The effects of the charge ratio and the concentration on the stability have been examined with absorption spectroscopy and ζ-potential measurements. The influence of the chemical structure of three isomeric photoacids on the size and shape of the nanoscale aggregates has been studied by dynamic light scattering and atomic force microscopy, revealing a direct correlation of the strength of the photoacid with the changes of the assemblies upon irradiation.

Facilitated Structure Formation in Isoporous Block Copolymer Membranes upon Controlled Evaporation by Gas Flow

The conventional fabrication of isoporous membranes via the evaporation-induced self-assembly of block copolymers in combination with non-solvent induced phase separation (SNIPS) is achieved under certain environmental conditions. In this study, we report a modification in the conventional fabrication process of (isoporous) flat sheet membranes in which the self-assembly of block copolymers is achieved by providing controlled evaporation conditions using gas flow and the process is introduced as gSNIPS. This fabrication approach can not only trigger and control the microphase separation but also provides isoporous structure formation in a much broader range of solution concentrations and casting parameters, as compared to fabrication under ambient, uncontrolled conditions. We systematically investigated the structure formation of the fabrication of integral asymmetric isoporous membranes by gSNIPS. A quantitative correlation between the evaporation conditions (causing solvent evaporation and temperature drop) and the self-assembly of block copolymers beginning from the top layer up to a certain depth, orientation of pores in the top layer and the substructure morphology has been discussed empirically.

Chemically Tailored Multifunctional Asymmetric Isoporous Triblock Terpolymer Membranes for Selective Transport

Membrane-based separation of organic molecules with 1-2 nm lateral dimensions is a demanding but rather underdeveloped technology. The major challenge is to fabricate membranes having distinct nanochannels with desired functionality. Here, a bottom-up strategy to produce such a membrane using a tailor-made triblock terpolymer featuring miscible end blocks with two different functional groups is demonstrated. A scalable multifunctional integral asymmetric isoporous membrane is fabricated by the solvent evaporation-induced self-assembly of the block copolymer combined with nonsolvent-induced phase separation. The membrane nanopores are readily functionalized using positively and negatively charged moieties by two straightforward gas-solid reactions. The pores of the post-functionalized membranes act as target-specific functional soft nanochannels due to swelling of the polyelectrolyte blocks in a hydrated state. The membranes show unprecedented separation selectivity of small molecules based on size and/or charge which demonstrates the potential of the proposed strategy to prepare next-generation nanofiltration membranes.

3D Analysis of Ordered Porous Polymeric Particles using Complementary Electron Microscopy Methods

Highly porous particles with internal triply periodic minimal surfaces were investigated for sorption of proteins. The visualization of the complex ordered morphology requires complementary advanced methods of electron microscopy for 3D imaging, instead of a simple 2D projection: transmission electron microscopy (TEM) tomography, slice-and-view focused ion beam (FIB) and serial block face (SBF) scanning electron microscopy (SEM). The capability of each method of 3D image reconstruction was demonstrated and their potential of application to other synthetic polymeric systems was discussed. TEM has high resolution for details even smaller than 1 nm, but the imaged volume is relatively restricted (2.5 μm)³. The samples are pre-sliced in an ultramicrotome. FIB and SBF are coupled to a SEM. The sample sectioning is done in situ, respectively by an ion beam or an ultramicrotome, SBF, a method so far mostly applied only to biological systems, was particularly highly informative to reproduce the ordered morphology of block copolymer particles with 32–54 nm nanopores and sampling volume (20 μm)³.

Stable Graphene-Based Membrane with pH-Responsive Gates for Advanced Molecular Separation

Graphene-based stable pH-responsive membranes (GPMs) were developed by alternative deposition of graphene oxide (GO) with polyethylenimine (PEI) in a layer-by-layer manner. Different from the conventional pore-blocking pH-responsive membranes, the size of the gaps among the GO sheets were first designed to respond to the surrounding pH. Atomic force microscopy was used to dynamically explore the internal structure alteration of GPM in the pH range from 3 to 11. It was found that the PEI molecules not only cross-linked the GO sheets through amide bonds to ensure the membrane stability but also reversibly altered the gate size of GPM in a certain extent according to the surrounding pH. In filtration, the gates of GPM were widened with the decreasing pH of the feed and vice versa. As a result, the permeate flux of GPM increased with the decreasing feed pH. More importantly, the molecular weight cutoff of GPM could be continuously regulated by the feed pH in a certain range; during the filtration of the polyvinylpyrrolidone (PVP) and polyethylene oxide (PEO) mixed solution, only PVP (58 kDa) could penetrate GPM at pH 11, while the left PEO (600 kDa) would penetrate GPM at pH 3. The controlled penetration through GPM led to a complete separation and recovery of the molecules in different sizes, which is highly desirable for advanced molecular separation in environmental applications.

Periodic Bicontinuous Structures Formed on the Top Surface of Asymmetric Triblock Terpolymer Thick Films

The combination of the nonsolvent-induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment is used to produce asymmetric and hydrophobic thick films having different long-range ordered network nanostructures, which are inaccessible via currently available membrane fabrication methods. We show that the disordered phase generated by NIPS on the material top surface can be transformed into a highly ordered bicontinuous network nanostructure during the SVA process without disrupting the substructure morphology. For instance, by using a straightforward blending approach, either a triply periodic alternating diamond (D^A) structure or a core-shell perforated lamellar (PL) phase was demonstrated on the skin layer of fully hydrophobic poly(1,1-dimethyl silacyclobutane)-block-polystyrene-block-poly(methyl methacrylate) (PDMSB-b-PS-b-PMMA) thick films. Such a material fabrication method, enabling the formation of a sponge-like substructure topped by a network phase having an excellent long-range order, provides an appealing strategy to facilitate the manufacture of next-generation membranes at large scale since these bicontinuous morphologies obviate the need of the nanochannel alignment.

A Review on Porous Polymeric Membrane Preparation. Part I: Production Techniques with Polysulfone and Poly (Vinylidene Fluoride)

Porous polymeric membranes have emerged as the core technology in the field of separation. But some challenges remain for several methods used for membrane fabrication, suggesting the need for a critical review of the literature. We present here an overview on porous polymeric membrane preparation and characterization for two commonly used polymers: polysulfone and poly (vinylidene fluoride). Five different methods for membrane fabrication are introduced: non-solvent induced phase separation, vapor-induced phase separation, electrospinning, track etching and sintering. The key factors of each method are discussed, including the solvent and non-solvent system type and composition, the polymer solution composition and concentration, the processing parameters, and the ambient conditions. To evaluate these methods, a brief description on membrane characterization is given related to morphology and performance. One objective of this review is to present the basics for selecting an appropriate method and membrane fabrication systems with appropriate processing conditions to produce membranes with the desired morphology, performance and stability, as well as to select the best methods to determine these properties.

Magnetic Responsive PVA Hydrogels for Remote Modulation of Protein Sorption

This work shows the ability to reversibly modulate the hydrophilicity of the hydrogels doped with iron oxide nanoparticles (MNPs) in a noninvasive way when exposed to a cyclic variation of the intensity (ON/OFF) of an external magnetic field. A reversible switching of surface contact angles was observed for magnetic PVA hydrogels when exposed to consecutive variation of the magnetic field intensity between 0 and 0.08 T. Motivated by the magnetic dependence of the hydrophilicity of these hybrid hydrogels, the impact of the magnetic field on protein sorption was also evaluated. The noninvasive regulation of protein sorption-released mechanisms was achieved by ON/OFF magnetic field switches, suggesting the possible influence of magnetic-induced hydrogel shrinking effect and changes of surface wettability on protein sorption. The capacity to magnetically modulate surface wettability and protein sorption make these magnetic hydrogels promising candidates for development of functional devices for tissue engineering, drug release applications, or biosensor systems, where the control of protein sorption and mobility are essential steps to improve the efficiency of these processes.

Biofouling-Resistant Porous Membranes with a Precisely Adjustable Pore Diameter via 3D Polymer Grafting

A facile route to biofouling-resistant porous thin-film membranes that can be fine-tuned for specific needs in diverse bioseparation, mass flow control, sensors, and drug delivery applications is reported. The proposed approach is based on combining two distinct macromolecular systems-a cross-linked poly(2-vinyl pyridine) network and a 3D-grafted polyethylene oxide (PEO) layer-in one robust porous material whose porosity can be adjusted within a wide range, covering the macroporous and mesoporous size regimes. Notably, this reconfigurable material maintains its antifouling properties throughout the entire range of pore size configurations because of a dense surface carpet of PEO chains with self-healing properties that are immobilized both onto the surface and inside the polymer network through what was termed 3D grafting. Experimental results are supplemented by computer simulations of a coarse-grained model of a porous membrane that shows qualitatively similar pore swelling behavior.

Self-assembly of block copolymers during hollow fiber spinning: an in situ small-angle X-ray scattering study

We investigated the self-assembly of block copolymers during hollow fiber membrane (HFM) fabrication by conducting in situ small angle X-ray scattering (SAXS) and ex situ scanning electron microscopy (SEM) studies. SAXS enables us to follow the structural rearrangements after extrusion at different distances from the spinning nozzle. The kinetics of the spinning process is examined as a function of the composition of block copolymer solutions and the spinning parameters. We studied the influence of the extrusion rate on the block copolymer microdomains and their self-assembly in weakly segregated and ordered solutions. The addition of magnesium acetate (MgAc2) leads to the ordering of micelles in the block copolymer solution already at lower polymer concentrations and shows an increased number of micelles with larger domain spacing as compared to the pristine solution. The SAXS data show the effect of shear within the spinneret on the self-assembly of block copolymers and the kinetics of phase separation after extrusion. It is observed that the ordering of micelles in solutions is decreased as indicated by the loss of crystallinity while high extrusion rates orient the structures perpendicular to the fiber direction. The structural features obtained from in situ SAXS experiments are correlated to the structure in the block copolymer solutions in the absence of shear and the morphologies in flat sheet and HF membranes obtained by ex situ SEM. This allows a systematic and comparative study of the effects varying the microdomain ordering within different block copolymer solutions and the formed membrane structures.