Synthesis and characterization of interpenetrating network (IPN) based levan-polyacrylamide hydrogels and their application in conservation of cultural heritage

In this study, an IPN based enzymatic levan-polyacrylamide hydrogel (EL-PA) was developed and charac-terized for its structural, morphological, rheological properties and swelling kinetics to underline hydrogel properties and its potential use in paper conservation. The addition of levan also led to changes in the viscoelastic behavior of the hydrogels, with the complex viscosity of EL-PA samples showing pronounced dependence on shear rate. The swelling and the overall surface area of the hydrogels were increased with the addition of levan into the polymer network. Source associated structural differences were found to be negligible such that both microbially produced linear and enzymatically produced branched forms of levan performed equally well. Solvent loaded hydrogels were then applied on an artifact, a 19th century book of Namik Kemal, and investigated using FTIR, SEM, XRD and colorimetric analysis. Old adhesive lay-ers were successfully removed, and hydrogels showed good compatibility and ease of application. This study has shown that levan has improved hydrogel properties and levan based systems bear high poten-tial in conservation science.(c) 2023 Consiglio Nazionale delle Ricerche (CNR). Published by Elsevier Masson SAS. All rights reserved.