Synthesis and Mesoscopic Organization of Perfluoroalkyl-Alkylene Methacrylate Monomers

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Abstract
Alcohols with perfluorinated segments, F(CF2) n —(CH2) m —OH; n = 8, 10, 12; m = 4, 6, 10; have been converted into methacrylates by a dicyclohexylcarbodiimide activated esterification reaction. The resulting methacrylates show two disordering transitions prior to isotropization. Polarization optical microscopy indicates the occurrence of smectic liquid crystal phases. Organic solutions of the amphiphilic methacrylates showed a strong decrease in the surface tension at low concentrations. Peculiar surface activity had already been observed for the compound with the shortest fluorocarbon segment. Needle shaped crystallites of the semifluorinated compounds are formed when hydrocarbon solutions of methacrylates with a perfluorododecyl substituent are cooled. The crystals can form a fine mesh network which encloses the solvent in the cavities. The size of the needle crystals and the internal dimensions of the network depend strongly on the crystallization conditions.