Hydrogen bonding interactions in miscible blends of poly(hydroxyether ester)s with poly(N-vinyl pyrrolidone)

Studies on the miscibility and intermolecular specific interactions in the blends of two structurally similar poly(hydroxyether ester)s, poly(hydroxyether terephthalate ester) (PHETE), and poly(hydroxyether benzoate) (PHEB) with poly(4-vinyl pyrrolidone) (PVPy) are reported. In the miscible blends there are intermolecular specific interactions between PHEEs and PVPy. It was found that intercomponent hydrogen-bonding interactions in PHETE/PVPy blends are much stronger than those in PHEB/PVPy blends. It seems that the higher ratio of hydroxyl to carbonyl groups results in the stronger intermolecular hydrogen bonding interactions. The difference in intermolecular specific interactions between the two miscible systems is interpreted on the basis of the impact of macromolecular structures on intermolecular specific interactions. The structural characteristics of macromolecular chains, such as chain connectivity, accessibility (or screening effect), and rigidity of the macromolecular chains have a profound effect on the intermolecular interactions. These factors constitute steric hindrance and reduce the specific interactions among functional groups. These factors can become dominant in the blends of polymers.