Crosslinked PVDF membranes for aqueous and extreme pH nanofiltration

© 2018 Elsevier B.V. Loose poly(vinylidene difluoride) nanofiltration membranes were crosslinked using a one-pot reaction with para-xylenediamine in alkaline conditions. The crosslinking reaction was characterized using ATR-FTIR and EDX-based elemental analysis as function of reaction time. Upon crosslinking, the retention of the membranes improved dramatically for rose Bengal (RB) (from 90% to 100%) and MO (from 49% to 91%) without significant loss of permeability. The physico-chemical changes of the membrane during the crosslinking reaction were further characterized through XRD, TGA, DSC and DMA. Crosslinking resulted in a strong decrease in crystallinity of the semi-crystalline PVDF and tensile strength and thermal stability. The 24 h crosslinked PVDF membranes were tested for NF application in extreme pH conditions. The membranes were found to be suitable in both extreme acidic and alkaline conditions (5 M HCl or NaOH). The RB retention was not affected at all by the extreme conditions. Although a small decrease in permeance was observed for the acid treated membrane, the permeance of the alkaline treated membrane was not affected. This proves that crosslinking is a suitable strategy to improve the stability of PVDF, especially in alkaline conditions where pristine PVDF is not applicable at all, and furthermore is a tool to decrease the MWCO.status: publishe

Green preparation process using methyl lactate for cellulose-acetate-based nanofiltration membranes

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Binaphthalene-based polymer membranes with enhanced performance for solvent -resistant nanofiltration

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Crosslinked PVDF-membranes for solvent resistant nanofiltration

© 2018 Elsevier B.V. Crosslinked poly(vinylidene difluoride) (PVDF) nanofiltration membranes were prepared and tested for solvent resistant nanofiltration (SRNF) and solvent tolerant nanofiltration (STNF, i.e. in solvent/water media) applications. The performance of the membranes was assessed by filtering ethanol (EtOH), iso-propanol (iPrOH), acetonitrile (ACN), dimethylformamide (DMF) or toluene (Tol) solutions containing Rose Bengal (RB), a 1017 Da solute. During these consecutive filtrations, the membranes displayed a solvent activation effect which was characterised by TEM, ATR-FTIR and via intermediate EtOH filtrations. This solvent activation resulted in a more permeable membrane (by a factor of 11), without loss in retention. Drying the membranes from MeOH resulted in a further increase of the RB retention in ACN and Tol to 98%. The stability of the membranes was characterised using SEM, weight loss analysis and ATR-FTIR. In STNF, a 99% RB retention was achieved from a 1:4 DMF/water mixture.status: publishe

Crosslinked Polyvinylnorbornene-Based Membranes as a New Class of Solvent-Resistant Nanofiltration Membranes

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Polyvinylnorbornene Gas Separation Membranes

Polynorbornenes are already used in a wide range of applications. They are also considered materials for polymer gas separation membranes because of their favorable thermal and chemical resistance, rigid backbone and varied chemistry. In this study, the use of 5-vinyl-2-norbornene (VNB), a new monomer in the field of gas separations, is investigated by synthesizing two series of polymers via a vinyl-addition polymerization. The first series investigates the influence of the VNB content on gas separation in a series of homo and copolymers with norbornene. The second series explores the influence of the crosslinking of polyvinylnorbornene (pVNB) on gas separation. The results indicate that while crosslinking had little effect, the gas separation performance could be fine-tuned by controlling the VNB content. As such, this work demonstrates an interesting way to significantly extend the fine-tuning possibilities of polynorbornenes for gas separations.status: publishe

Tunable Prussian blue analogues for the selective synthesis of propargylamines through A(3) coupling

© 2018 The Royal Society of Chemistry. M 1 [Co(CN) 6 ] 2/3 -type Prussian blue analogues (M 1 -Co PBAs) were studied as catalysts for the synthesis of propargylamines via A 3 coupling of phenylacetylene, benzaldehyde and piperidine. Cu 0.86 Zn 0.14 -Co PBA was the best catalyst for the reaction by combining the high conversion obtained with Cu-Co PBA with the excellent selectivity obtained with Zn-Co PBA.status: publishe

Novel heterogeneous ruthenium racemization catalyst for dynamic kinetic resolution of chiral aliphatic amines

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Ni-Catalyzed reductive amination of phenols with ammonia or amines into cyclohexylamines

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