Effects of complexation on the water vapor sorption of polymer alloys

Water sorption measurements of the polyion complex between poly(p-styrenesulfonic acid) (PS_tS) and poly(4-vinylpyridine) (PVP) were carried out to study the effect of the Coulombic interactions between a polyanion and a polycation. The properties of the polyion complex were examined using infrared spectroscopy (IR), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and elemental analysis. It was found that the ionic bonds between and groups led to the formation of a 1:1 polyion complex between PS_tS and PVP. The nitrogen 1s level in the PS_tS/PVP polyion complex increased 2.1 eV above its level for PVP, indicating protonation of the pyridine group. In addition, at 293 K and 303 K the water sorption of the complex was larger than that of the sum of the component polymers. In the preceding paper, the water sorption properties of the polyion complex between poly(acrylic acid) (PAA) and PVP were studied. Compared to this complex, the PS_tS/PVP complex absorbed more water relative to its components. This may be due to the stronger acid strength of the over the ? COOH groups.