However, we acknowledge that the absolute values of stiffness and toughness are relatively low compared to existing double-network or interpenetrating-network elastomers , which approximately have stiffness of 10 6 Pa and tensile toughness of 10 6 J/m 3 . To further improve the network mechanical properties, we exploit the morphology afforded by block copolymer assembly to tune the network stiffness. Unlike conventional polymer networks of an amorphous morphology, the networks self-assembled by LAL triblock copolymers can have various kinds of ordered morphology. As the morphology transitions from sphere to lamellae, the glassy domains percolate throughout the whole microstructure to result in a high stiffness . To this end, we use the middle block with the highest fraction of reversible bonds (𝜆=0.25) and increase 𝑓 from 0.11 to 0.33. Microscopically, for 𝑓 = 0.33, the polymer self-assembles to a lamellar microstructure, as revealed by SAXS measurements in Fig. . In situ SAXS/tensile measurements reveal the increase of the distance between two neighboring glassy domains along the direction of stretching (Fig. ). Yet, the polymer remains transparent because of small characteristic length scales, ~37 nm, much below the wavelength of visible light (Table ).