Wettabilities of Organosiloxane Thin Films Derived from SiCl₃-Terminated Carbosilane Dendrons on Mica

We prepared submonolayers, monolayers, and multilayers of organosiloxanes derived from the second to fourth generation (G2−G4) SiCl 3 -terminated carbosilane dendrons on mica by spin-casting. The surface properties of these films, such as wettabilities, surface tensions, works of adhesion with various liquids, pore size, and surface coverage, were investigated by means of contact-angle measurements. All G2−G4 films exhibit high hysteresis of ∼20°, probably due to molecular scale chemical heterogeneity and surface roughness. The surface tensions of the G2−G4 monolayers are similar: γ S (total) = ∼29 mJ/m 2, γ S d (dispersive) = ∼24 mJ/m 2, and γ S p (polar) = ∼5 mJ/m 2 . However, only γ S d (∼21 mJ/m 2 ) contributes to the surface tensions of the multilayers, suggesting that the underlying polar mica substrate is significantly screened by the dendron multilayers. Works of adhesion ( W SL ) for water, glycerol, dimethylformamide, methylene iodide, squalane, and hexadecane on the films were measured. The multilayers exhibit a lower W SL d (dispersive) than the monolayers (difference of ∼3 mJ/m 2 ), consistent with a decrease of γ S d from monolayers to multilayers. Furthermore, both the average pore size and the surface coverage of the G2−G4 monolayers were estimated to be 0.31−1.1 nm 2 and ∼77%, respectively.