Preliminary study on structural integrity and properties of surface fluorinated silicone rubbers

Direct Fluorination as Method of Improvement of Operational Properties of Polymeric Materials

“…Information about the wetting mode is relevant for superhydrophobization of polymer surfaces due to the complex effect of increasing the content of fluorine in the surface layer and surface morphology features that can be created by directional etching [41] or by introducing fillers into a polymer [34]. Such surfaces were obtained by oxygen-free fluorination of silicone rubbers (θ a(H2O) = 143.7 • ) [42,105,106] and carbon fiber, which is a component of a composite material based on polyvinylidene fluoride (θ a(H2O) = 153 • ) [34]. Particular attention should be paid to the effect of "sticky superhydrophobicity" of polybutylene terephthalate fiber mats as a result of liquid-phase fluorination [32]: when a drop of water is not separated from the surface by gravity even in the case of non-wetting surface (θ a(H2O) = 156 • ).…”

“…This information can be useful at the sampling stage in order to obtain reproducible results and correct interpretation of the data. However, hysteresis phenomena during wetting of modified surfaces are discussed only in a few papers [72,98,105,107]. Le Roux et al [72], F. J. du Toit & Sanderson [98] associate an increase in water wetting hysteresis with an increase in the roughness of the surfaces of polyphenylene oxide and polypropylene caused by their etching as a result of fluorination, Gekas et al [107] indicate a correlation between the hysteresis and porosity for commercial ultrafiltration membranes based on cellulose triacetate and polysulfone.…”

Moisture Barrier Properties of Silicone Rubber Surface Layers Fluorinated at Different Temperatures

“…In accordance with the high resolution spectrum results, surface element analysis results given in Table 2, based on XPS survey spectra (not shown), also show the highest or lowest fluorine content of the sample F25 or the sample F85, and the lowest carbon content of the sample F55. In addition, although chain scission is difficult to be analyzed even by XPS, it must occur during direct fluorination of the SIR material, which is especially true for the pure silicone without protection of the backbone from inorganic nanofillers [23], and the probability of chain scission should increase with fluorination temperature. It should be the changes in chemical composition and structure, the chain scission, and the heat released during the fluorination that cause stress concentration or an uneven shrinkage of the surface layer and lead to surface nanostructuration and even the formation of pores or pits.…”