Dehydration of binary methyl acetate–water mixtures under neutral, acidic, and basic conditions was carried out by using PERVAP composite membranes based on polyvinyl alcohol and poly(1-vinylpyrrolidone- co -2-(dimethylamino)ethyl methacrylate) P(VP- co -DMAEMA). The effects of an acid (HCl) and a base (NaOH) on the separation performance of the membrane during the pervaporation process were investigated. The pH-responsive nature of membranes has been confirmed by swelling tests and analysis of the chemical structure of polymeric membranes. In addition, a mechanism of ring-opening of VP units is proposed and correlated to the changes of membrane separation performance.
In nature, various specific reactions only occur in spatially controlled environments. Cell compartment and subcompartments act as the support required to preserve the bio-specificity and functionality of the biological content, by affording absolute segregation. Inspired by this natural perfect behavior, bottom-up approaches are the focus to develop artificial cell-like structures, detrimental for understanding relevant bioprocesses and interactions or to produce tailored solutions in the field of therapeutics and diagnostics. In this review, we discuss the benefits of constructing polymer-based single and multicompartments (capsules and giant unilamellar vesicles (GUVs)), equipped with biomolecules as to mimic cells. In this respect, we outline key examples of how such structures have been designed from scratch, namely starting from the application-oriented selection and synthesis of the amphiphilic block copolymer. We then present the state-of-the-art techniques for assembling the supramolecular structure while permitting the encapsulation of active compounds and the incorporation of specific ion channels (peptides/proteins), essential to support in situ reactions, e.g., to replicate intracellular signaling cascades. Finally, we briefly discuss important features that these compartments offer and how they could be applied to engineer the next generation of microreactors, therapeutic solutions, and cell models.
Tailor‐made poly(N‐vinylpyrrolidone‐co‐(2‐[dimethylamino]ethyl methacrylate)) P(NVP‐co‐DMAEMA) and poly(N‐vinylpyrrolidone‐co‐N‐vinylimidazole) P(NVP‐co‐PNVIm) with defined monomer molar ratio are synthesized via free radical polymerization. The random copolymers are fully characterized and then blended with polyvinyl alcohol (PVA) to investigate their chemical and thermal properties as membrane materials. Composite membranes are further prepared from the PVA/copolymer blends on a porous support, which are evaluated in terms of separation performance for the dehydration of ethanol by pervaporation. The membranes prepared from the blends exhibit up to four times higher water permeances than pristine PVA membrane, albeit the selectivity is slightly lower. Nevertheless, the membranes from blends with a ratio of 95:5 (PVA/copolymer) show improved selectivity and higher permeance values compared to the commercial PERVAP™ 4155–80, especially the blends composed by the copolymers of coPDMAEMA60 and coPDMAEMA20. The membrane prepared from the blend containing the homopolymer coPDMAEMA100 exhibits the highest water/ethanol selectivity and shows stable separation performance throughout the whole long‐term stability test. Thus, this study demonstrated that by synthesizing tailored copolymers (rather using the commercial ones) and blending with PVA, the separation performance of membranes can be significantly improved and tuned for specific dehydration processes.
Tailor‐made poly(vinyl alcohol)‐b‐poly(styrene) copolymers (PVA‐b‐PS) for separation membranes are synthesized by the combination of reversible‐deactivation radical polymerization techniques. The special features of these di‐block copolymers are the high molecular weight (>70 kDa), the high PVA content (>80 wt%), and the good film‐forming property. They are soluble only in hot dimethyl sulfoxide, but by the “solvent‐switch” technique, they self‐assemble in aqueous media to form micelles. When the self‐assembled micelles are cast on a porous substrate, thin‐film membranes with higher water permeance than that of PVA homopolymer are obtained. Thus, by using these tailor‐made PVA‐b‐PS copolymers, it is demonstrated that chemical cross‐linkers and acid catalysts can no longer be needed to produce PVA membranes, since the PS nanodomains within the PVA matrix act as cross‐linking points. Lastly, subsequent thermal annealing of the thin film enhances the membrane selectivity due to the improved microphase separation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.