Spreading of Trisiloxanes EO3 and EO9 Polyethylene Oxide Surfactant over Hydrophobic Substrates

The spreading of aqueous dispersions of trisiloxane with various polyethylene oxide chain length surfactant solutions over hydrophobic surfaces is considered from experimental point of view. It is shown that the transfer of surfactant molecules from the droplet onto the hydrophobic surface changes the wetting characteristics in front of the drop making them useful in water-based coatings for plastics and agricultural adjuvant for plant spray. The surfactant molecules increase the solid-vapor interfacial tension and hydrophilize the initially hydrophobic solid substrate just in front of the spreading drop. This process causes water drops to spread over time. The behavior of the drops containing surfactant molecules varied according the surface active molecules that it contains, temperature and the degree of hydrophilicity of the surfactant. The trisiloxane surfactants with polyethylene oxide chain length of nine (EO9) and three EO3 were used on this experiment. Different features of these spreading phenomena were observed. Initial spreading is followed by a period in which the radius of spread increases linearly with time. Water droplets containing the EO9 were more active than the droplets containing the EO3, and they spread more rapidly. On the othe