Synthesis and physico-chemical properties of poly(N-vinyl pyrrolidone)-based hydrogels with titania nanoparticles

Poly(N-vinyl pyrrolidone) (PVP)-based hydrogels with titania nanoparticles (TN) were synthesized by the sol–gel method for the first time and were characterized in different states (native, freeze-dried, air-dried to constant weight and ground to powder, or swollen to constant weight in H(2)O or D(2)O) by various methods such as wide-angle and small-angle X-ray and neutron scattering, neutron spin-echo (NSE) spectroscopy, and scanning electron microscopy. The static (static polymer–polymer correlation length (mesh size), associates of cross-links and PVP microchains) and dynamic (polymer chain relaxation rate, hydrodynamic polymer–polymer correlation length) structural elements were determined. The incorporation of titania nanoparticles into PVP hydrogel slightly increases the size of structural inhomogeneities (an increase in the static and dynamic polymer–polymer correlation length, the formation of associates of cross-links and PVP chains). Titania nanoparticles have an impact on the microstructure of the composite hydrogel and form associates with sizes from 0.5 to 2 µm attached to PVP hydrogel pore walls. The PVP and TN/PVP hydrogels show a high degree of water swelling. Moreover, the presence of titania nanoparticles in TN/PVP increases the number of water adsorption cycles compared to PVP hydrogel. The high swelling degree, bacteria-resistant and antimicrobial properties against Staphylococcus aureus allow considering NT/PVP hydrogels for medical applications as wound coatings.