MIXED MONOLAYERS FOR THE DESIGN OF STRUCTURED SURFACES TO INDUCE ORIENTED 3-D CRYSTALLIZATION

Mixed monolayers containing two different amphiphiles C19H39CONHCH2CH2 CO2H (A) and C19H39CONH2 (B) were designed in order to form a two-dime nsional (2-D) crystalline solid solution in which the A-type molecules form domains within the sea of B-type molecules. A ''continuous'' 2-D arrangement of the aliphatic chains was expected, driven by the amide hydrogen bonding requirement; a tendency for the formation of the emb eded A-type domains should be provided by the interactions between the -CH2CH2CO2H head group moieties. The mixed monolayers served to promo te the oriented nucleation of silver propionate 3-D crystals attached at the monolayer-solution interface. Only the A-type domains induced s ilver propionate crystallization whereas the B-type domains were essen tially inert. The mixed A + B monolayers were found to be efficient nu cleators down to a 1:10 molar ratio, providing proof for the existence of A-type domains. Additional information such as the structure and i on-binding properties of the mixed monolayers was furnished by specula r X-ray reflectivity and grazing incidence X-ray diffraction using syn chrotron radiation.