NEW APPROACH TO PREPARATION OF GELATINE/SiO2 HYBRID SYSTEMS BY THE SOL-GEL PROCESS

A new method of synthesis of a series of hybrid gelatine/silica systems, based on solgel technique, was developed in this study which was aimed at achieving the maximum compatibility of the gelatine/silica systems prepared in a wide range of gelatine-silica ratios (from 30 to 80 wt. % of gelatine). The systems were characterized by X-ray diffraction, SEM, TEM, FT-IR, and TG techniques. The obtained materials showed a diverse structure due to the fact that a part of silica formed a homogeneous composite with gelatine, while another part formed microspherical particles of complicated structure. A possibility was tested for employing branched polyalkoxysiloxanes as crosslinkers in the preparation of gelatine-silica hybrids

Fluorocarbosilane-Based Protective Coatings for Concrete

The effectiveness of protective coatings based on 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OFTES) in protecting concrete surfaces against water was tested. For the synthesis of OFTES, 2,2,3,3,4,4,5,5-octafluoropentanol, which is a by-product in the synthesis of poly(tetrafluoroethylene), was used. The proposed silane is a cheaper alternative to the fluorinated organosilicon compounds currently used. The coatings were deposited by the sol-gel method. As a result of the creation of chemical bonds between the concrete surface and the silane, a coating was created that permanently increases the hydrophobicity of the concrete. Fluorine chains attached to silicon atoms are an effective barrier that prevents access to water and limits its impact on the concrete surface. As a result of the proposed silanization, the concrete surface obtained a hydrophobic character at contact angles of up to 126°, and the water absorption of the concrete decreased by up to 96%

Ionic Liquids as Solvents for Rhodium and Platinum Catalysts Used in Hydrosilylation Reaction

A group of imidazolium and pyridinium based ionic liquids has been synthetized, and their ability to dissolve and activate the catalysts used in hydrosilylation reaction of 1-octane and 1,1,1,3,5,5,5-heptamethyltrisiloxane was investigated. An organometallic catalyst as well as inorganic complexes of platinum and rhodium dissolved in ionic liquids were used, forming liquid solutions not miscible with the substrates or with the products of the reaction. The results show that application of such a simple biphasic catalytic system enables reuse of ionic liquid phase with catalysts in multiple reaction cycles reducing the costs and decreasing the amount of catalyst needed per mole of product

Piperidinium and Pyrrolidinium Ionic Liquids as Precursors in the Synthesis of New Platinum Catalysts for Hydrosilylation

Six new air-stable anionic platinum complexes were synthesized in simple reactions of piperidinium [BMPip]Cl or pyrrolidinium [BMPyrr]Cl ionic liquids with platinum compounds ([Pt(cod)Cl2] or K2[PtCl6]). All these compounds were subjected to isolation and spectrometric characterization using NMR and ESI-MS techniques. Furthermore, the determination of melting points and thermal stability of the above derivatives was performed with the use of thermogravimetric analysis. The catalytic performance of the synthesized complexes was tested in hydrosilylation of 1-octene and allyl glycidyl ether with 1,1,1,3,5,5,5-heptamethyltrisiloxane. The study has shown that they have high catalytic activity and are insoluble in the reaction medium which enabled them to isolate and reuse them in consecutive catalytic cycles. The most active complex [BMPip]2[PtCl6] makes it possible to conduct at least 10 catalytic runs without losing activity which makes it an attractive alternative not only to commonly used homogeneous catalysts, but also to heterogeneous catalysts for hydrosilylation processes. The activity of the studied catalysts is also affected by the kind of anion and, to some extent, the kind of cation

Silylenenickel(0) or silyl(silynene)platinum(II) complexes by reaction of Si[(NCH2But)2C6H4-12] with [NiCl2(PPh3)2] [Ni(cod)2] or [PtCl2(PPh3)2]

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Catalysis of hydrosilylation processes with the participation of ionic liquids

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

Efektywna metoda wytwarzania powłok przeciwmgielnych (przeciwroszeniowych) na bazie dwufunkcyjnych polisiloksanów

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

The Rapeseed Oil Based Organofunctional Silane for Stainless Steel Protective Coatings

The earlier obtained organosilicon derivatives of rapeseed oil were used for the production of coatings protecting steel surface against corrosion. Vegetable oils have been hitherto used for temporary protection of metals against corrosion, while thanks to the synthesis of appropriate organosilicon derivatives, it is now possible to create durable protective coatings. Due to the presence of alkoxysilyl groups and the use of the sol-gel process, the coatings obtained were bonded to the steel surface. The effectiveness of the coatings was checked by electrochemical methods and steel surface analysis