Hydrophobization of cotton fabrics was carried out with the use of bifunctional polysiloxanes with various contents of functional groups. Polysiloxanes contained in their structure groups capable of bonding to substrates (trialkoxysilyl or glycidyl ones) and fluoroalkyl groups showing surface activity. Two methods of surface modification were compared: (1) a one-step method via the chemical modification of fabrics with solutions of bifunctional polysiloxanes and (2) a two-step method-via preliminary modification of fabrics with silica sol followed by chemical modification with solutions of bifunctional polysiloxanes. The hydrophobicity was determined by measuring the water contact angle by drop profile tensiometry. Changes in the surface topography were examined by scanning electron microscopy. Superhydrophobic fabrics were obtained by a simple one-step method by the chemical modification in solutions of bifunctional polysiloxanes. The fabrics maintained their superhydrophobic properties even after multiple washings. The modification does not cause any changes visible to the naked eye, such as stiffening, color changes or a decrease in mechanical properties.
Ineffectiveness of the chemicals applied so far for waterlogged wood conservation created the need to develop new more, efficient and reliable agents. As an alternative, a new method with the use of organosilicon compounds differing in chemical composition and molecular weight has been investigated. The results obtained show the potential of organosilicons as consolidants in waterlogged wood conservation able to effectively stabilise wood dimensions upon drying. The best wood stabilisers were low-molecular organosilicons enable to penetrate the cell wall as well as chemicals with functional groups capable of interacting with wood polymers and forming stabilising coatings on the cell wall surface. The best anti-shrink efficiency values were obtained for (3-Mercaptopropyl)trimethoxysilane, (3-Aminopropyl)triethoxysilane, 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, reaching 98, 91 and 91%, respectively. Most of the applied organosilicons reduced wood hygroscopicity, which limits the risk of further dimensional changes of wood exposed to a variable air moisture content and potentially reduces wood biodegradation. In the light of our studies, the proposed method of waterlogged wood conservation with organosilicons is potentially reversible in the case of siloxanes and amino-silanes as well as retreatable, which complies with the requirements of the conservation ethics.
This mini-review briefly describes the recent progress in the design and development of catalysts based on the presence of ionic liquids. In particular, the focus was on heterogeneous systems (supported ionic liquid (IL) phase catalysts (SILPC), solid catalysts with ILs (SCILL), porous liquids), which due to the low amounts of ionic liquids needed for their production, eliminate basic problems observed in the case of the employment of ionic liquids in homogeneous systems, such as high price, high viscosity, and efficient isolation from post-reaction mixtures.
Epoxy functional (poly)siloxanes are one of the most important classes of modified silicones. Due to high reactivity of epoxy group and specific features of siloxane chain, they can make an excellent raw material for synthesis of hybrid materials. Results obtained in this study have shown that both the modification of epoxy resins with epoxy functional disiloxanes as well as the application of polysiloxanes with long polysiloxane chains and a specified content of epoxy groups makes it possible to produce hybrid materials of very good thermal stability. Crosslinking reactions were carried out with use of four diamines of which the best one appeared to be 4,4 0-diaminodiphenylmethane. The highest thermal stability was found in the case of hybrid materials obtained from epoxy functional polysiloxanes.
Organofunctional silanes with more sterically hindered substituents at the silicon atom than the typical methoxy (ethoxy) group have lately been frequently used as silane coupling agents, in polymer coupling systems, sol-gel processes and also as interpenetrating polymer network substrates. New and very efficient synthetic ways leading to organofunctional silanes of the above type with methacryl, amine, chloro and isocyanato functional groups are proposed here. Catalytic transesterification and/or alcoholysis of chloropropyltrialkoxysilanes followed by nucleophilic substitution has been employed.
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.
Epoxyfunctional carbosilanes are a group of silane coupling agents, which because of their structures and properties are applied as crosslinking agents, adhesion promoters or modifiers of fillers and mineral surfaces. Methods of syntheses [equation (2) and (3)], properties and characteristics as well as main directions of applications of epoxyfunctional carbosilanes, especially 3-glicydoxypropyltrialkoxysilanes [Formula (I)] and β-(3,4-epoxycyclohexyl)ethyltrialkoxysilanes [Formula (II)] have been presented. The first ones are used mainly as silane coupling agents while the other ones as modifiers of polymers. Technology, developed by authors, of 3-glicydoxypropyltriethoxysilane synthesis basing on catalytic process of allyl-glicydyl ether hydrosilylation is a base of this silane production at the UNISIL Co.,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.