Wetting studies of molecularly engineered surfaces

The wettability studies of mixed monolayers containing hydrophobic (CH₃) and hydrophilic (OH) terminal groups are discussed. We describe and explain a concentration-driven transition in the contact angles of liquids on mixed monolayers. It is suggested that this phenomenon is due to a possible surface phase transition, resulting in the formation of a prewetting water layer. The self-assembly method opens exciting new possibilities of engineering smooth surfaces. Chemical properties fine-tuned at the molecular level will lead to new levels of control of physicochemical properties of surfaces. Long-chain thiol derivatives can be used in model surfaces to attain control of surface roughness and chemical properties. Combinations of surface functionalities give a large variety of surfaces, thus allowing a systematic control of surface free energy, and chemical affinity.