FLEXIBLE CRYOSTRUCTURATED PVA-BASED HYDROGELS AS MATERIALS FOR ADVANCED SENSING APPLICATIONS
Angelica Giovagnoli1, Stefano Scurti1, Giada D’Altri1, Lamyea Yeasmin1,2, Valentina Di Matteo1, Isacco Gualandi1 Maria Cristina Cassani1, Daniele Caretti1, Barbara Ballarin1
1Department of Industrial Chemistry “Toso Montanari”, University of Bologna, Via Piero Gobetti 85, 40129 Bologna, Italy
2Department of Applied Science and Technology, Politecnico of Turin, C.so Duca degli Abruzzi 24, 10129 Turin, Italy
angelica.giovagnoli2@unibo.it
Flexible polymeric materials have highlighted several advantages including low density, easy processing and excellent resistance under mechanical stimuli. Nowadays polymer-based flexible materials have seen wide spread, thanks to their attractive properties that make them suitable for sensing in different fields (healthcare, security, environmental monitoring, food safety, agriculture) and for cutting-edge energy storage. Among them, PVA-based hydrogel, can be considered a promising material for their versatility and safety.1-2
In this work, physical cross-linked PVA hydrogels were cryo-structurated in acidic media by freezing-thawing (F-T) methodology. Different parameters (e.g. number of F-T cycles) have been investigated to evaluate the influence of the preparation method on the final material properties.3 Moreover, their porous structure creates a preferred path for charges and external factors as vapours, gases and liquid solutions giving the possibility to be evaluated as a promising matrix for sensing applications studied by electrochemical measurements. Their flexibility and the introduction of specific polymers into the PVA-hydrogel matrix has led to develop piezo-responsive sensors4 and motion sensor.
Furthermore, halochromic dyes based on an azo-substituted diketopyrrolpyrrole (DPP) structure were integrated in the hydrogels to obtain an host-guest system able to switch the color under environmental pH changes. The halocromic and flexible sensors developed have a quick response and color reversibility under both liquids and vapours expositions, keeping the matrix structure integrity with potential application in the field of environmental and food sensing.