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Kataliza procesów hydrosililowania z udziałem cieczy jonowych

Bartlewicz Olga, Szymańska Anna, Jankowska-Wajda Magdalena, Dąbek Izabela, Maciejewski Hieronim

Wiadomości Chemiczne

2021

[Z] 75, 1-2

5--29

Hydrosilylation is a fundamental and elegant method for the laboratory and industrial synthesis of organosilicon compounds. The hydrosilylation reaction is usually performed in a single-phase homogeneous system. A major problem, particularly in homogeneous catalysis, is the separation of catalyst from the reaction mixture. The presence of metals in the reaction products, even in trace quantities, is unacceptable for many applications, therefore efforts have been made at applying heterogeneous catalysts or immobilised metal complexes in order to obtain high catalytic activity and easy product isolation at the same time. One of the methods for producing such catalysts is the employment of ionic liquids as agents for the immobilization of metal complexes. Biphasic catalysis in a liquid-liquid system is an ideal approach through which to combine the advantages of both homogeneous and heterogeneous catalysis. The ionic liquids (ILs) generally form the phase in which the catalyst is dissolved and immobilized. In our research we have obtained a number of catalytic systems of such a type which were based on rhodium and platinum complexes dissolved in phosphonium, imidazolium, pyridinium and ammonium liquids. Currently, there has a common trend to obtain heterogenized systems that combine advantages of homogeneous and heterogeneous catalysis, which makes the hydrosilylation process more cost- effective. Such integration of homo- and heterogeneous catalysts is realized in several variants, as supported IL phase catalysts (SILPC) and solid catalysts with ILs layer (SCILL). Although all the above systems show high catalytic activities, their structure is unknown. This is why we have made attempts to modify selected ionic liquids (corresponding to our most effective systems) and we have applied them as ligands in the synthesis of platinum and rhodium complexes. Another group of catalysts comprises anionic complexes of rhodium and platinum which were obtained by reactions between halide complexes of metals and a respective ionic liquid. Most of the obtained complexes are solids insoluble in hydrosilylation reagents and are characterized by a high catalytic activity. A considerable development of heterogeneous catalysts of this type and their application in many hydrosilylation processes can be expected in the future. This mini-review briefly describes the recent progress in the design and development of catalysts based on the presence of ionic liquids and their applications for hydrosilylation processes.

Effective method for the production of anti-fog (dew-resistant) coatings based on bifunctional polysiloxanes

Dąbek Izabela, Kaczmarek Marta, Karasiewicz Joanna, Guliński Jacek, Maciejewski Hieronim

Polimery

2020

T. 65, nr 11-12

807--815

Anti-fog (dew-resistant) coatings were produced employing as active components bifunctional polysiloxanes containing polyether (hydrophilic and polar) groups and trialkoxysilyl groups (permitting durable adhesion to glass surface). These bifunctional polysiloxanes were obtained as a result of consequent hydrosilylation of allyl polyethers and vinyltrialkoxysilane with the use of poly(dimethyl-co-hydromethyl)siloxane. The effect of structure of the polysiloxane used (length of siloxane chain, length of polyether chain, content of functional groups) and its concentration of the coating performance were analyzed. The designed preparation permits easy production of a durable anti-fog and dew-resistant coating from widely accessible raw materials and with no need of special pretreatment of glass surface.

Powłoki przeciwmgielne (przeciwroszeniowe) wytworzono z zastosowaniem – jako składników aktywnych – dwufunkcyjnych polisiloksanów zawierających grupy polieterowe (hydrofilowe i polarne) oraz grup trialkoksysililowych (umożliwiających trwałe przyłączenie do powierzchni szkła). Zbadano wpływ struktury zastosowanego polisiloksanu (długość łańcucha siloksanowego, długość łańcucha polieterowego, zawartość grup funkcyjnych) i jego stężenia na efektywność tworzenia powłok. Opracowany preparat umożliwia łatwą produkcję trwałej powłoki przeciwmgielnej i przeciwroszeniowej z powszechnie dostępnych surowców i bez potrzeby specjalnego przygotowania powierzchni szklanej.