Miscibility and interactions in chitosan acetate/poly(N-vinylpyrrolidone) blends

Graphical abstract: In the present study, the blends of chitosan (Ch) and poly(vinylpyrrolidone) (PVP) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). Research highlights: → The purpose of paper was the evaluation of the miscibility PVP with chitosan. → The thermal properties, WAXD and FTIR analysis were investigated. → The influence of molecular weight on the properties blends has been discussed. → The results reported in this paper provide an indication that blends are poor miscible. - Abstract: In the present study, the blends of chitosan (Ch) and poly(N-vinylpyrrolidone) (PVP) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). WAXD patterns of homopolymers and their blends indicated that blending of amorphous materials, such as PVP, with semicrystalline polymer, such as chitosan gives rise to an amorphous structure. From thermal curves the glass transitions temperature have been determined and compared. The thermal results indicated that in the solid ChA/PVP blends the components are poorly miscible. The FTIR spectra of film blends, in the carbonyl stretching region of PVP and the hydroxyl stretching bands of chitosan have been analyzed. The observed shift of these bands and the change of their shape depends on (I) the blend composition, on (II) the chemical structure of chitosan {chitosan in its amine form (Ch) or chitosan acetate (ChA)}, and on (III) the molecular weight of PVP, whereas the influence of temperature in the range of 298-403 K seems to be negligible.