Structure of cetyltrimethylammonium bromide films obtained by evaporation-induced precipitation method

Homogeneous cetyltrimethylammonium bromide (CTAB) films on a solid Si substrate were obtained by the solvent evaporation-induced precipitation method from an alcohol-aqueous solution. The CTAB molecules in the films are oriented almost normally to the substrate plane. Their orientation depends on both the substrate surface state and the CTAB concentration in its initial solution. The CTAB films produced using 0.5–10 wt.% solutions have a structure similar to that of the bulk substance. The CTAB molecule methylene chains form crystal packing with an orthorhombic subcell that results in the appearance of Davydov's splittings in the IR-spectra.