Systematic variation of membrane casting parameters to control the structure of thermo-responsive isoporous membranes

Mocan, Merve; Wahdat, Hares; Kooij, Hanne M. van der; Vos, Wiebe M. de; Kamperman, Marleen

doi:10.1016/j.memsci.2017.11.047

Cited by 21 publications

(23 citation statements)

References 31 publications

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“…Such performance is highly desirable for purely size-based separations. Conformational changes of polymer chains resulting from external stimuli make the membranes less competitive candidates for sharp size-selective separations. − Zhang et al reported that the PI–PS–PAA membrane demonstrated significant pH responsiveness and hysteresis, and its rejection capacity decreased in the presence of 10 mM MgCl 2 . To eliminate the responsiveness of the chains, the membrane needed to go through a series of treatments.…”

Section: Resultsmentioning

confidence: 99%

Development of a High-Flux Thin-Film Composite Nanofiltration Membrane with Sub-Nanometer Selectivity Using a pH and Temperature-Responsive Pentablock Co-Polymer

Bar

Çağlar

et al. 2019

ACS Appl. Mater. Interfaces

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Producing block co-polymer-based nanofiltration (NF) membranes with sharp molecular weight cutoffs via an efficient method exhibiting persistent size-based separation quality is challenging. In this study, this challenge was addressed by reporting a facile approach to fabricate pentablock co-polymer (PBC)-based thin-film composite (TFC) NF membranes. The PBC, consisting of temperature-responsive Pluronic F127 (PEO-b-PPO-b-PEO) middle blocks and pH-responsive poly(N,N-(diethylamino)ethyl methacrylate) end blocks, were synthesized by atom-transfer radical polymerization. This polymer was then attached electrostatically to the surface of polysulfone/sulfonated polyether-sulfone support membranes fabricated using a non-solvent-induced phase separation technique. The conformational changes of the PBC chains in response to pH and temperature determined the pure water flux and neutral solute (PEG 1000) rejection performance of TFC membranes. Permeability of the membranes increased from 13.0 ± 0.63 to 15.9 ± 0.06 L/m 2 •h• bar and from 6.7 ± 0.00 to 13.9 ± 0.07 L/m 2 •h•bar by changing the solution pH from 4 to 8.5 and temperature from 4 to 25 °C, respectively. The pH-and temperature-responsive conformational changes did not affect the PEG 1000 rejection and membrane pore radius, which remained constant at ∼89% and ∼0.9 nm, respectively. This important finding was attributed to the high grafting density of co-polymer chains, resulting in spatial limitations among the grafted chains. The pore size of ∼0.9 nm achieved with the proposed membrane design is the smallest size reported so far for membranes fabricated from block copolymers. TFC membranes demonstrated high stability and maintained their flux and rejection values under both static (storage in an acidic solution for up to 1 month) and dynamic (filtering PEG 1000 solution over 1 week) conditions. Pentablock copolymers enable a NF membrane with a sharp molecular weight cutoff suitable for size-selective separations. The membrane fabrication technique proposed in this study is a scalable and promising alternative that does not involve complex synthetic routes.

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Section: Resultsmentioning

confidence: 99%

Development of a High-Flux Thin-Film Composite Nanofiltration Membrane with Sub-Nanometer Selectivity Using a pH and Temperature-Responsive Pentablock Co-Polymer

Bar

Çağlar

et al. 2019

ACS Appl. Mater. Interfaces

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“…Solvent evaporation induced a concentration change in the block copolymer solution in the high concentration region near the surface, followed by microphase separation along the gradient, thus leading to the formation of cylindrical domains and the highly swollen layer. In this phase separation process, most of the constructed hydrophobic domain diffused to the channels, because the interface part of the solvent/nonsolvent exchange provided in these channels was especially larger than that of the surface. − …”

Section: Strategies For Generating Sr-ppmsmentioning

confidence: 99%

Design of Switchable Enzyme Carriers Based on Stimuli-Responsive Porous Polymer Membranes for Bioapplications

Qiao

2021

ACS Appl. Bio Mater.

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Design of efficient enzyme carriers, where enzymes are conjugated to supports, has become an attractive research avenue. Immobilized enzymes are advantageous for practical applications because of their convenience in handling, ease of separation, and good reusability. However, the main challenge is that these traditional enzyme carriers are unable to regulate the enzymolysis efficiency or to protect the enzymes from proteolytic degradation, which restricts their effectiveness of enzymes in bioapplications. Enlightened by the stimuli-responsive channels in the natural cell membranes, conjugation of the enzymes within flat-sheet stimuli-responsive porous polymer membranes (SR-PPMs) as artificial cell membranes is an efficient strategy for circumventing this challenge. Controlled by the external stimuli, the multifunctional polymer chains, which are incorporated within the membranes and attached to the enzyme, change their structures to defend the enzyme from the external environmental disturbances and degradation by proteinases. Specifically, smart SR-PPM enzyme carriers (SR-PPMECs) not only permit convective substrate transfer through the accessible porous network, dramatically improving enzymolysis efficiency due to the adjustable pore sizes and the confinement effect, but they also act as molecular switches for regulating its permeability and selectivity. In this review, the concept of SR-PPMECs is presented. It covers the latest developments in design strategies of flat-sheet SR-PPFMs, fabrication protocols of SR-PPFMECs, strategies for the regulation of enzymolysis efficiency, and their cutting-edge bioapplications.

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“…[22,47,48] Generally, the BCP molecular characteristics, casting solution properties, casting parameters, and immersion precipitation conditions are considered determinant factors for the successful preparation of asymmetric isoporous BCP membranes via SNIPS. The influence of aforementioned factors on the structural characteristics of SNIPS membranes have been mainly studied by using polystyrene (PS)-based amphiphilic BCPs, for example, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), [49] Polystyrene-block-Poly(2-vinylpyridine) (PS-b-P2VP), [50] Polystyrene-block-Poly(ethylene oxide) (PS-b-PEO), [51] polystyrene-block-poly(N-isopropyl acrylamide) (PSb-PNIPAM), [52] polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA), [53] polystyrene-block-poly(acrylic acid) (PS-b-PAA). [54] A complete list of different BCPs, used for the membrane preparation following the SNIPS process thus far (including more than 20 BCPs of different properties), can be found in ref.…”

Section: Introductionmentioning

confidence: 99%

How does Micro‐ and Macro‐Phase Separation of Block Copolymers Affect the Formation of Integral Asymmetric Isoporous Membranes? A Review on Effective Factors

Foroutani

Ghasemi

2022

Macro Materials & Eng

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Self-standing isoporous membranes based on amphiphilic block copolymers (BCPs) are an outstanding candidate for efficient separation processes. Such fascinating membranes have been generated through combining the BCP self-assembly (micro-phase separation) together with the classical non-solvent induced phase separation (macro-phase separation), known as SNIPS process. However, the controllability, reproducibility, and cost-effectiveness of the process along with the mechanism for pores generation are still challenging in the SNIPS strategy, especially when new BCP or conditions are utilized. It is mainly due to the narrow efficacy window of numerous variables influencing the desired structure formation. In this review, first, an overview of the one-step readily scalable SNIPS technique and the stepwise explanation of the process are given. Then the formation mechanism of SNIPS membranes, according to the related hypotheses and assumptions proposed on the basis of experimental evidence so far, is presented and discussed. As the main focus , governing factors in the SNIPS process which affect the preparation and structural characteristics of final membrane structures are entirely reviewed and interpreted. This review will help to have a better understanding of the connection between determinant factors and final membrane structure, which facilitates successful preparation of BCP membranes via SNIPS.

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Systematic variation of membrane casting parameters to control the structure of thermo-responsive isoporous membranes

Cited by 21 publications

References 31 publications

Development of a High-Flux Thin-Film Composite Nanofiltration Membrane with Sub-Nanometer Selectivity Using a pH and Temperature-Responsive Pentablock Co-Polymer

Development of a High-Flux Thin-Film Composite Nanofiltration Membrane with Sub-Nanometer Selectivity Using a pH and Temperature-Responsive Pentablock Co-Polymer

Design of Switchable Enzyme Carriers Based on Stimuli-Responsive Porous Polymer Membranes for Bioapplications

How does Micro‐ and Macro‐Phase Separation of Block Copolymers Affect the Formation of Integral Asymmetric Isoporous Membranes? A Review on Effective Factors

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