Hydrophobic Materials Based on Fluorocarbofunctional Spherosilicates

Abstract

Consecutive hydrosilylation-based syntheses were performed of silsesquioxanes containing mixed groups 1H,1H,2H,2H-perfluorooctyl (PFD) or octafluoropentyloxypropyl (OFP) and trimethoxysilylethyl (TMS) in different stoichiometric ratios. The presence of TMS makes it possible to form covalent bonds with substrates due to the reactivity of this group. All obtained derivatives were applied to hydrophobization of glass plates and by comparison of water contact angles (WCA) on modified surfaces the effect of silsesquioxane structure as well as TMS and fluoroalkyl group contents on hydrophobic properties was determined. Moreover, an additional glass plates surface modification was performed in order to obtain superhydrophobic surfaces. Two silica types of different specific surface (300 and 130 m 2 /g) and particle size (7 and 16 nm) parameters were used in this case for initial surface modification in order to increase its roughness. Irrespectively of particle size of applied silica, a dependence was found between the increase in water contact angle and the number of fluoroalkyl substituents in a molecule.

Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

“…The latter groups can react with surface hydroxyl groups and, moreover, due to their longer chain (compared to trialkoxysilyl group present in the derivatives 1-3) they can cause a greater surface diversification [45,46]. The most likely reason for this disparity is the different nature of surface hydroxyl groups.…”

“…The hydrosilylation was carried out with two pairs of olefins: 1,1,2,2,3,3,4,4-octafluoropentyl allyl ether and vinyltrimethoxysilane, as well as 1,1,2,2,3,3,4,4-octafluoropentyl allyl ether and glycidyl allyl ether, according to the procedure reported in the literature [44,45]. Two families of derivatives have been obtained in which the ratios of respective functional groups were 7:1 (the derivatives 1 and 2 containing fluoroalkyl and trimethoxysilyl or glycidoxypropyl groups, respectively) and 4:4 (the derivatives 3 and 4, containing fluoroalkyl and trimethoxysilyl or glycidoxypropyl groups, respectively).…”

“…In this way, silsesquioxanes were synthesized which contain also trimethoxysilyl or glycidyl groups besides fluoroalkyl groups. The reactivity of trimethoxysilyl and glycidyl groups causes that they can form stable bonds with the substrate as a result of reactions with hydroxyl groups present on the surface [45,46].…”

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

“…1), but only a few previous studies have described cage molecules containing 4, 6, 10, or 12 silsesquioxane fragments. By contrast, over 1000 previous studies have reported octameric cage molecules [RSiO 1.5 ] 8 (cubic structures) with different organic groups at the silicon atom [2,[11][12][13][14][15][16][17][18][19][20][21][22] (see Table 1). M a n u s c r i p t 3 This prevalence of octameric structures among structures with the same composition but different sizes is not accidental, and there are several possible explanations.…”

Fabrication of superhydrophobic cotton fabrics by a simple chemical modification

“…These compounds, when applied to the modification of glass, made it possible to create superhydrophobic coatings (Maciejewski et al 2014a(Maciejewski et al , b, 2015. However, in the case of glass surfaces and glass fibers (as well as mineral fibers), alkoxy groups easily undergo condensation due to the different character of the Si-OH groups on glass surfaces in contradistinction to the C-OH groups present on surfaces of natural fibers (Valdez-Gonzalez et al 2009).…”