We
study the effect of dehydration on the structure and mechanical
properties of anisotropic lamellar hydrogels, consisting of alternative
stacking of several thousands of nanoscale rigid bilayers from amphiphilic
poly(dodecyl glyceryl itaconate) (PDGI) and submicroscale soft hydrogel
layers from hydrophilic polyacrylamide (PAAm) networks. We found that
the layered microstructure is well preserved with dehydration, and
a ductile–brittle transition occurs at the critical water content.
This transition is related to the rubbery–glassy transition
of the PAAm layers, which occurs at 58 wt % water content and is much
higher than 26 wt % of bulk PAAm hydrogels. Such specific behavior
of the lamellar hydrogels indicates that the dynamics of the submicroscale
PAAm hydrated layer intercalated between the rigid bilayers are very
different from its bulk state.