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Enhanced catalytic activity of zeolitic imidazolate frameworks (ZIF-8) polyelectrolyte complex composites membranes by laser etching

Yu Ting, Kitiyanan Boonyarach, Dubas Stephan Thierry

Materials Science Poland

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2024

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Vol. 42, No. 1

52--61

EN

The effect of laser etching on the surface properties of composite polyelectrolyte complex (PEC) based membranes as mixed matrix membranes was studied. The PECs were prepared by the stoichiometric mixing of cationic PDDA (poly(diallyl dimethyl ammonium chloride)) and anionic PSS (poly(sodium 4-styrene sulfonate)) as polyelectrolytes with various contents of ZIF-8 as filler. Composite membranes usually display improved bulk properties depending on the nature of the filler, but the surface properties are often dictated by the matrix covering the surface. The PEC composite membranes were then subjected to laser etching, resulting in the enhanced exposure of embedded ZIF-8 particles within the PEC structure in an attempt to improve the surface properties of the composite membrane. The crystal structure, morphology, and distribution of zinc at the PECs surface, before and after laser etching, were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. In order to evaluate the improvement of the surface properties of the laser-etched membranes, a model experiment involving a catalytic reaction was chosen. The pristine and laser treated surfaces were tested for their catalytic activity for the transesterification of triglycerides present in soybean oil with methanol at a temperature of 150°C. Interestingly, the laser-etched PECs displayed substantially enhanced activity compared to the original composite PEC membranes as a result of surface erosion. These results could be interesting for the future development of composite membranes with improved surface properties where the filler needs to expose the surface of the membranes.

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State of water in chitosan /tripolyphosphate polyelektrolyte complex membranes for pervaportation

Gierszewska-Drużyńska M., Ostrowska-Czubenko J.

Polish Journal of Applied Chemistry

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2009

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Vol. 53, nr 1

15-21

EN

Polyelectrolyte complexes (PECs) are known as new interesting membrane materials applicable in industry, medicine and pharmacy. In this work PEC membranes from chitosan (Ch) and pentasodium tripolyphosphate (TPP) designed for pervaporation w'ere prepared by dipping Ch membranes in TPP solution. The PEC formation between Ch and TPP was confirmed by FTIR spectroscopy. Various amounts of w'ater were added into the dry ChATPP hydrogels to cause them to swell, and the amounts of water in various states were determined by the DSC ice-melting technique. Three types of water in hydrogel membranes w'ere identified: non-freezing bound water, freezing bound water, and freezing free w'ater. States of water in Ch/TPP and Ch membranes were compared and the effect of ionic crosslinking on the non-freezing water content was discussed.

3

Medical polyurethanes with different hard segments content obtained from polycaprolactone diol , aliphatic diisocyanates and butanediol

Gibas I., Janik H.

Polish Journal of Applied Chemistry

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2009

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Vol. 53, nr 1

9-14

EN

Three series of segmented polyurethanes (PUs) with biomedical destination were synthesized using two-step catalyzed polymerization method. PUs with a broad range of hard segments content were obtained from the following components: 1,6-diisocyanatohexane or dicyclohexylmethane diisocyanate, poly(s-caprolactone)diol (olygodiol) and 1,4-butanedioI (chain extender). Chemical and physical structures were examined with the use of IR and DSC methods. Swelling behavior in water, oil and saline, contact angle and roughness were also investigated. The samples are crystalline, slightly hydrophilic with different surface properties, which can be controlled in a wide range by molar ratio of the components used for the synthesis. The results of hexane/water extracts tests do not exclude them to be applied for medical applications. The further studies to use the obtained PUs as medical non-solvent coatings are being continued.