Synthesis and characterization of tri-block fluorinated-n-alkanes

A series of triblock semifluorinated n-alkanes of general formula F(CF2)(n)(CH2) (CF2)(m)F (n = 6, 8 and m = 4, 6, 8) have been synthesized and characterized. The synthesis of triblock compounds was performed in two different ways according to the length of the hydrogenated moiety. Coupling of two molecules of beta-(perfluoro-n-alkyl)ethyl iodides leads to the triblock materials F(CF2)(6)(CH2)(4)(CF2)(6)F and F(CF2)(8)(CH2)(4)(CF2)(8)F. The synthesis of compounds with larger hydrogenated part is accomplished in two steps by the addition of perfluoro-n-alkyl iodide F(CF2)(n)l to 1,5-hexadiene and 1,7-octadiene, respectively to give the diiodo-adducts which are subsequently deiodinated to the final triblock products F(CF2)(6)(CH2)(6)(CF2)(6)F, F(CF2)(6)(CH2)(8)(CF2)(6)F, F(CF2)(8)(CH2)(6)(CF2)(8)F and F(CF)(8)(CH2)(8)(CF2)(8)F. The obtained triblock semifluorinated n-alkanes are characterized by low surface free energies with good lubricant properties usable as additives in ski-wax formulations. (C) 2007 Elsevier B.V. All rights reserved.