  Soft materials capable of large inelastic deformation play an essential role
in high-performance nacre-inspired architectured materials with a combination
of stiffness, strength and toughness. The rigid "building blocks" made from
glass or ceramic in these architectured materials lack inelastic deformation
capabilities and thus rely on the soft interface material that bonds together
these building blocks to achieve large deformation and high toughness. Here, we
demonstrate the concept of achieving large inelastic deformation and high
energy dissipation in soft materials by embedding microstructured thermoplastic
fibers with sacrificial bonds and hidden lengths in a widely used elastomer.
The microstructured fibers are fabricated by harnessing the fluid-mechanical
instability of a molten polycarbonate (PC) thread on a commercial 3D printer.
Polydimethylsiloxane (PDMS) resin is infiltrated around the fibers, creating a
soft composite after curing. The failure mechanism and damage tolerance of the
composite are analyzed through fracture tests. The high energy dissipation is
found to be related to the multiple fracture events of both the sacrificial
bonds and elastomer matrix. Combining the microstructured fibers and straight
fibers in the elastomer composite results in a ~ 17 times increase in stiffness
and a ~ 7 times increase in total energy to failure compared to the neat
elastomer. Our findings in applying the sacrificial bonds and hidden lengths
toughening mechanism in soft materials at the microscopic scale will facilitate
the development of novel bioinspired laminated composite materials with high
mechanical performance.
