Surface properties of films containing poly(vinyl alcohol) having an n-alkylthio group at one end

Abstract Surface properties of the poly(vinyl alcohol) (PVA) blend films composed of conventional PVA and PVA having an n-alkylthio end group of 4–18 carbon atoms (R n -PVA; n = 4–18) were studied by contact angle measurements and XPS analysis. In the blend films, R n -PVA distributed preferentially on the air side surface (but not on the opposite side) depending on the chain length of n-alkylthio end groups. The critical surface tensions, γ c , and surface-free energies, γ s , of the R 12- PVA PVA-HCA blend were the lowest of all R n- PVA PVA-HCA blends. The polar component of the surface free energy, γ p s , of the blends with R n -PVA of n = 8–16 was substantially zero, from which these film surfaces were deduced to be predominantly covered with n-alkyl chains. The C/O ratio, the ratio of the carbon atoms to the oxygen atoms in the surface layer estimated by XPS analysis, had some correlation with γ c and γ s . However, it was suggested that the surface properties were affected not only by the composition of the surface but also by the arrangement of the n-alkyl chains on the surface.