Miscibility of poly(N-vinyl-2-pyrrolidone) with poly(hydroxyether of phenolphthalein) and polyacrylonitrile

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with poly(hydroxyether of phenolphthalein) (PHP) and polyacrylonitrile (PAN) were prepared by casting from a common solvent and studied by differential scanning calorimetry. It was found that PVP was miscible with PHP and all the PVP/PHP blends were homogeneous and had a single, composition-dependent glass transition temperature (T-g). A FTIR study revealed that a hdyrogen-bonding interaction occurs between the components of PVP/PHP blends, and its strength is higher than that in pure PHP. The miscibility of PVP with PHP is hence proposed to be due to the hydrogen-bonding interaction between the components. PVP was also found to exhibit miscibility with PAN, and all the blend films obtained were homogeneous. The observed miscibility of PVP with PAN is also thought to be a result of hydrogen-bonding interactions between the ct-hydrogens of PAN and the proton acceptor groups of PVP.