Self-assembly of perfluorodecanoic acid with cationic copolymers: Ultra-low energy surfaces and mesomorphous structures

Solid complexes of poly[diallyldimethylammonium chloride)-co-(N-methyl-N-vinylactetamide)] with perfluorodecanoate were prepared with a 1:1 stoichiometry. The surface energies of the fluorinated complexes were in the range of 13 to 15 mN/m independent of the fluorine amount present. This result was attributed to the formation of a surface of closely packed trifluoromethyl groups. All of the complexes farm thermally stable, self-organized mesophases with body-centered cubic or body-centered tetragonal symmetry. The unit cell volume shrinks from 100 to 40 nm(3) with increasing charge density of the polyelectrolyte. This shrinkage is accompanied by an increase in the bulk density from 1.44 to 1.87 g/cm(3). From wide-angle X-ray scattering it was derived that the packing order of the perfluoroalkyl chains strongly depends on the charge density and increases in a stepwise manner from amorphous to crystalline.