Cryogels loaded with nanostructured fluids studied by ultra-small-angle X-ray scattering

The combination of nanostructured fluids (NSFs), such as micellar solutions or microemulsions and highly-retentive hydrogels, such as PVA-based cryogels, represents nowadays a promising and innovative approach in the field of conservation of cultural heritage, as it enables the highest control available during cleaning interventions. However, at present, little is known about the confinement of NSFs into PVA-based cryogels. In the present work, small-angle X-ray scattering (SAXS) and ultra-small-angle X-ray scattering (USAXS), combined with fluorescence correlation spectroscopy (FCS), were used to address this issue. Two significantly different NSFs were selected for this purpose, based on anionic or nonionic surfactants, and they were confined into four different gels: two single PVA and two PVA/PVA “twin-chain polymer networks” (TC-PNs). The analysis of the experimental results shows that surfactant nature is crucial in determining the interaction of NSFs with the gels’ polymer network. Moreover it was demonstrated that loading NSFs on PVA-based cryogels does not significantly affect the short-range nanostructure of neither the NSFs nor the gels, preserving the cleaning performances of the combined system.