Fluoroalkylsilane versus Alkylsilane as Hydrophobic Agents for Silica and Silicates

Abstract

Hydrophobic powders were obtained via surface modification of silica or magnesium silicate with selected silanes. A modified precipitation method, carried out in an emulsion system, was used for monodisperse silica synthesis, while magnesium silicate was precipitated in a traditional water system. Functionalization of the obtained inorganic supports was performed with selected alkylsilanes: one newly synthesized, 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OPF), and two commercial, octadecylsilane (ODS) and octyltriethoxysilane C 14 H 32 O 3 Si (OCS), in amounts of 3, 5, or 10 weight parts by mass of SiO 2 . It was determined how the chemical modification of the silica or magnesium silicate surface affected its physicochemical properties. The dispersive characteristics of both unmodified and functionalized silica-based systems were evaluated. The morphology and microstructure of the samples obtained were analyzed using scanning electron microscopy. The parameters of porous structure of the prepared systems were evaluated on the basis of BET equation as well as nitrogen adsorption/desorption isotherms. Wettability tests as well as elemental analysis of the obtained inorganic oxide hybrids were also performed. In order to verify the effectiveness of silica and magnesium silicate surface functionalization with selected silanes, FTIR spectra were investigated. The resulting experimental data allowed calculation of the degree of coverage of the silica-based systems with modifying agents.

Fluoroalkylsilanes with Embedded Functional Groups as Building Blocks for Environmentally Safer Self-Assembled Monolayers

“…Interpretation of EIS measurements is usually performed by fitting the impedance data to an equivalent electrical circuit, which should be representative of the physical processes taking place in the system under investigation. In particular, EIS enables us to follow how the modification of ITO electroactive surface affects the charge transfer by a redox mediator, such as K 4 [Fe(CN) 6 ]/K 3 [Fe-(CN) 6 ].…”

“…Chemicals. Perfluoromethyl ester C 5 F 11 C(O)OMe 16 and perfluorohexansulfonyl fluoride C 4 F 9 SO 2 F 35 were produced by Miteni S.p.A. via electrochemical fluorination (ECF); 36,37 (3- 6 ], KNO 3 , and sodium citrate were purchased from Sigma-Aldrich and used without further purification. Ultrapure water purified by the Milli-Q plus system (Millipore Co., with resistivity over 18 MΩ cm) was used in all cases.…”

“…Each measurement was repeated 3 times. A 0.1 M KNO 3 solution containing 1 mM K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] (1:1) mixture was used. All electrochemical measurements were conducted in a conventional three-electrode cell using a saturated calomel electrode (SCE) reference electrode and a Pt wire counter electrode in a N 2 atmosphere at room temperature.…”

Hydrophobic Thin Films from Sol–Gel Processing: A Critical Review

“…A possible strategy to obtain superhydrophobic surfaces is fabricating rough surfaces modified with low surface energy molecules such as fluoroalkysilanes (FAS). The use of FAS has always been investigated because of the ease of obtaining hydrophobic, chemically and mechanically resistant surfaces, compared to classical alkylsilanes [87]. In recent years, however, the presence of fluorinated agents has banned their use because of their dangerous effect on human health [88].…”

Recent progress in the preparation, properties and applications of superhydrophobic nano-based coatings and surfaces: A review

“…Only a few researchers have reported the use of FAS as a precursor without combining them with other agents to produce superhydrophobic surfaces. 177 (Heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane or HDFTS, 178 tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) 179 and 3-(2,2,3,3,4,4,5,5octafluoropentyloxy) propyltriethoxysilane (OPF) 180 are some commonly used fluorosilane precursors.…”