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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

2024

Vol. 42, No. 1

52--61

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.

Sieci metalo-organiczne typu MOF jako przykład mateiałów wykorzystywanych w ukierunkowanej terapii przeciwnowotworowej

Samaszko-Fiertek Justyna, Khalatyan Alina, Dmochowska Barbara, Ślusarz Rafał, Madaj Janusz

Wiadomości Chemiczne

2023

[Z] 77, 1-2

35--53

MOF materials (metal-organic frameworks) are a relatively organic-inorganic (hybrid) materials. Due to very good adsorption properties, large specific surfaces and large pore volumes, these compounds are quite intensively studied, and the number of organic-inorganic hybrids obtained is growing year by year. Most MOF compounds are crystalline two- or three-dimensional organometallic structures. They are an example of hybrid materials that are made of both inorganic and organic component. The inorganic part is represented by metal ions/clusters, while the organic skeleton contains neutral or charged organic linkers [1-3]. The most common metal cations included in organometallic lattices are: Zn2+, Cu2+, Cr3+, Al3+ and Mg 2+. Organic ligands can be neutral, positively or negatively charged, but they must be primarily electron pair donors, which means that they have nitrogen or oxygen-containing functional groups in their structure. Ligands’ role is to stitch these building units together to create extended framework structures, while metal ions provide structural integrity and durability. These materials have a well-developed specific surface and a large pore volume (570-3800 m2/g). Thanks to the presence of coordination bonds in the structure, the skeletons of organometallic networks are flexible. Based on literature data, several methods of cancer treatment using MOFs are distinguished, e.g.: using passive targeting, active targeting, physicochemical targeting, and in a particular case using all three strategies (Fig. 2, Table 1) [12,13]. The ongoing work on the modification of the synthesized MOF structures based on zinc ions allows the preparing various types of cancer drugs based on their durability and high porosity. The ability to synthesize multifunctional Zn-MOFs is a new chapter in the design of chemotherapeutic agents. A particular example is ZIF-8. The combination of different strategies for the influence of the pH value of the environment or photochemical elements gives the opportunity to use the compounds in imaging and cancer diagnosis.