Influence of Polyhydroxyl Additives on the Mechanical Properties of Poly(acrylic acid)/Polyvinylpyrrolidone Complex Films

Poly(acrylic acid)/polyvinylpyrrolidone (PAA/PVP) hydrogen-bonded complexes are of growing interest as functional materials for biomedical applications. However, the influence of polyhydroxyl additives, such as polyols and sugars, on complex formation and material performance remains insufficiently understood. This study aimed to elucidate how polyhydroxyl compounds affect the physical properties of PAA/PVP complexes. Dried PAA films were brought into contact with aqueous PVP solutions containing various additives (glycerol, sugar alcohols, or sugars), and the resulting hydrogels were dried to form films. Their swelling behavior in water and PBS, thermal stability, and mechanical properties were comparatively evaluated. Sugar alcohols markedly improved swelling and flexibility, whereas sugars showed limited effects. Glucitol exhibited intermediate performance due to a high tendency toward intramolecular hydrogen bonding in aqueous media. Mechanistic analysis suggested that sugar alcohols act in a chaperone-like manner during complex formation, promoting microphase-separated structures composed of hydrogen-bonded domains and free segment regions. These findings provide new molecular insight into designing PAA/PVP-based materials with additives for biomedical applications.