Synthetic composite materials constructed by hybridizing multiple components are typically unsustainable due to inadequate recyclability and incomplete degradation. In contrast, biological materials like silk and bamboo assemble pure polymeric components into sophisticated multiscale architectures, achieving both excellent performance and full degradability. Learning from these natural examples of bio-based “single-component” composites will stimulate the development of sustainable materials. Here, we report a single-component “Silk nacre,” where nacre’s typical “brick-and-mortar” structure has been replicated with silk fibroin only and by a facile procedure combining bidirectional freezing, water vapor annealing, and densification. The biomimetic design endows the Silk nacre with mechanical properties superior to those of homogeneous silk material, as well as to many frequently used polymers. In addition, the Silk nacre shows controllable plasticity and complete biodegradability, representing an alternative substitute to conventional composite materials.
Flexible and transparent substrates play a fundamental role as a mechanical support in advanced electronic devices. However, commonly used polymer films, such as polydimethylsiloxane, show low tear resistance because of their crack sensitivity. Herein, inspired by the excellent mechanical robustness of the skin and its fibrous structure, an epoxy‐resin‐based composite with a flat silk cocoon as a reinforcing fiber network is fabricated. With only 1 wt% of silk fiber, the tensile strength and modulus of the as‐prepared composite film are considerably increased by 300% and 612% compared to those of pure resin, while still maintaining flexibility and transparency. More importantly, the composite shows remarkable tear resistance: without fracture after ≈30 000 tensile cycles. The potential application of such transparent composite films as mechanically robust substrates for flexible electronics is also demonstrated. In addition, this study represents a bioinspired strategy to construct high‐performance functional composite materials.
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