Figure 5: Toughening double network hydrogels with superstructures.
(a,b) Birefringence patterns showing the reversible change in the stripe superstructures of double network (DN) gel during stretching in the direction parallel (a) and vertical (b) to the strip direction. Images in rows (ai) and (bi) were observed under the crossed polarizers. Images in rows (aii) and (bii) were observed under the crossed polarizers with 530-nm tint plate. Double-headed arrow shows the tensile direction. Tensile strain, ε, is defined as (L−L0)/L0, in which L0 and L are the lengths of the gel before and during elongation, respectively. Scale bar, 2 mm. (c) Stress–strain curves of DN gels stretched in the directions parallel (blue) and vertical (red) to the stripe direction.
