Poly(vinyl alcohol) (PVA)–based cryogels represent high valuable materials that find a wide range of applications from biomedicine to cultural heritage preservation. [1, 2] The final performances of such materials are strictly connected to their micro– and macroscopical features that, in turn, can be selectively altered by varying the number of freeze–thawing (FT) cycles, the freezing temperature, and the use of selected additives. In particular, the use of mixture of PVA having different molar mass and degree of acetylation results in “twin-chain” (TC) gels having interconnected, sponge-like porosity finding major applications in Cultural Heritage preservation.[3]
In this contribution, a new class of TC-PVA cryogels based on the functionalization of PVA with sebacic, adipic or succinic acid is presented. Prior to gel formulation, the functionalized PVAs were studied by means of SEC (MALS–Visco–RI) and ¹H NMR analysis to access details on the overall microstructure. Subsequently, a library of PVA cryogels was prepared employing sebacic, adipic or succinic acid-decorated PVAs.[4, 5] An in-dept characterization of the final gels was conducted via ¹H NMR, CLSM, SAXS, and rheology, and resulted in the material’s structure-property evaluation.
The final materials were tested on ideal as well as real substrates from the Peggy Guggenheim collection (Venice, Italy) to evaluate their performances during cleaning practices of interest in Cultural Heritage preservation.
Counterintuitively, the TC-cryogels with lower adaptivity on surfaces and the highest tortuosity were the most efficient in entrapping and removing superficial dust on jagged surfaces.
Such result reveals that the gel's capacity of slowing down molecular motions at the boundary surface between substrate and gel is the driving force to ensure a more favorable interaction between the gel and the surface.
We believe that this new finding will be valuable for the design of materials with enhanced performances at the surface of objects, also beyond Cultural Heritage preservation scopes and aim.

References
[1] W. Wan et al., in Polymeric Cryogels., Adv. Polym. Sci., 2014, 263.
[2] L. Pensabene Buemi et al., Heritage Science, 2020, 8, 1-16.
[3] R. Mastrangelo et al., Proc. Natl. Acad. Sci. USA, 2020, 117, 7011-7020.
[4] D. Bandelli et. al., J. Colloid Interf. Sci., 2024, 657, 178-192.
[5] R. Mastrangelo et al. Adv. Funct. Mater. 2024, 34, 2404287.

Damiano Bandelli

Universita degli Studi di Firenze

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