Surface study of poly(vinyl alcohol) and poly(N-vinyl-2-pyrrolidone) miscible blends

Poly (vinyl alcohol) (PVAL)/poly (N-vinyl-2-pyrrolidone) (PVP) blends are studied by DSC, FT-IR and X-ray photoelectron spectroscopy (XPS). The special interaction (hydrogen bonding) between PVAL and PVP was investigated by FT-IR. The carbonyl stretching of PVP shifts to a lower wavelength by approximately 25 cm^-1. A single Tg was observed for all PVAL/PVP blends, suggesting miscibility of the blends. XPS results show that PVAL enriched on the surface of the PVAL/PVP blends. The hydrogen bonding induces a relatively small shift of 0.3-0.4 eV in the O 1 s BE of the oxygen atom in the carbonyl and hydroxyl groups. Although the interaction between PVAL and PVP is very strong, the effects of this interaction on the surface structure and composition are limited