Figure 4. Mechanical properties of composites with semi-flexible PIC networks and flexible PAAm networks.

(a) Storage modulus G′ as a function of time for PIC/PAAm hybrid hydrogels at T=50 °C, showing the formation of the PAAm network within the pre-formed PIC network. De decrease in G′ with increasing (AAm) is the result of the Hofmeister effect. (b) The differential modulus K′ of the PIC/PAAm hybrid hydrogels increases with AAm concentration in the linear regime at low stress, but decreases with AAm concentration in the high-stress regime. The solid lines represent the slopes of the curves. (c) K′ as a function of stress for PIC/PAAm hybrid hydrogels at T=50 °C with 36 mg ml⁻¹ (0.5 M) AAm and increasing concentrations of crosslinker MBAA. (d) K′ as a function of stress for conjugated (open symbols) and non-conjugated polymer networks (solid symbols, data from b).