  We investigate the linear viscoelasticity of polymer gels produced by the
dispersion of gluten proteins in water:ethanol binary mixtures with various
ethanol contents, from pure water to 60% v/v ethanol. We show that the complex
viscoelasticity of the gels exhibits a time/solvent composition superposition
principle, demonstrating the self-similarity of the gels produced in different
binary solvents. All gels can be regarded as near critical gels with
characteristic rheological parameters, elastic plateau and characteristic
relaxation time, which are related one to another, as a consequence of
self-similarity, and span several orders of magnitude when changing the solvent
composition. Thanks to calorimetry and neutron scattering experiments, we
evidencea co-solvency effect with a better solvation of the complex
polymer-like chains of the gluten proteins as the amount of ethanol increases.
Overall the gel viscoelasticity can be accounted for by a unique characteristic
length characterizing the crosslink density of the supramolecular network,
which is solvent composition-dependent. On a molecular level, these findings
could be interpreted as a transition of the supramolecular interactions, mainly
H-bonds, from intra- to interchains, which would be facilitated by the
disruption of hydrophobic interactions by ethanol molecules. This work provides
new insight for tailoring the gelation process of complex polymer gels.
