Multifunctional hydrophobic coatings based on siloxane polymers with branched perfluoroalkyl substituents: Fast, simple and ecologically safe synthesis in active media

Abstract

This article discusses the synthesis of polyorganosiloxanes with 1,1,1,2,2,3,3-heptafluoro-4,4-bis(trifluoromethyl)pentyl (Rf = CF3CF2CF2C(CF3)2(CH2)3-) perfluoroalkyl substituents for the sake of hydrophobic coatings. Using perfluoroalkyl di- and trifunctional alkoxysilane derivatives, linear and branched siloxanes were obtained. The main emphasis of this work based on the simplicity of the proposed condensation approach in the active medium, the environmental component of the application of alkoxysilanes instead of toxic chlorosilanes, and the low cost and harmlessness of the perfluorinated compounds used. Varying the nature of the active medium, the ratio of reagents and temperature, it was shown that the polymers with the highest molecular weight (Mn ˃ 40,000) are obtained by refluxing the reaction mixture for 40 h in the ratio RfSi(OEt)3 + СH3COOH = 1:15. The hydrophobizing ability of all the obtained polymers was tested by measuring the contact angle (θ) on glass and aluminum. Branched polymers with Mn = 37,600 and 42,000 showed the best results (θ ˃ 108). In addition, the work shows the prospects of hydrophobization ability of epoxy resins with the copolymers of triethoxysilane with branched perfluoroalkyl substituents and phenyltriethoxysilane in comparison with their known analogs.