A Transparent, Skin‐Inspired Composite Film with Outstanding Tear Resistance Based on Flat Silk Cocoon

Abstract

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.

Ice‐Templated, Large‐Area Silver Nanowire Pattern for Flexible Transparent Electrode

“…Smaller λ or higher dosage are favorable for building more conductive pathways, yet simultaneously blocks the optical path, leading to poor transmittance. According to our previous work, [ 39–45,56–59 ] λ can be tuned by changing the freezing dynamics in the directional freezing method. It is correlated to the freezing temperature.…”

Emerging Silk Material Trends: Repurposing, Phase Separation and Solution-Based Designs

“…Silk fibers spun in vivo and in vitro continue to find new medical applications. Examples include in vitro generated multi-functionalized sutures [55] and custom in vivo spun fibers that are incorporated into resins [56]. A key tool that has made these new features possible is our ability to fully reverse-engineer the spun fiber [14,48].…”

New Silk Road: From Mesoscopic Reconstruction/Functionalization to Flexible Meso‐Electronics/Photonics Based on Cocoon Silk Materials

“…Stretchable E-Skin: A transparent, skin-inspired silk-resin composite film with outstanding tear resistance was fabricated using a flat silk cocoon as a reinforcing fiber network (Figure 8a). [98] The flat silk cocoons were produced by silkworms with continuous silk fibers, which retain the outstanding mechanical advantage of the natural silk fibers. With only 1% of silk fiber content, the tensile strength and modulus of the fat-silk-cocoon-reinforced composite films increase significantly by 300% and 612%, respectively, compared to those of the pure resin films while maintaining good flexibility and transparency.…”

“…In multiple cutting and healing cycles, the mechanical and electrical properties of the (middle and right image) Reproduced with permission. [98] Copyright 2020, Wiley-VCH. b) Self-healing properties of the Gr/SF/Ca 2+ films.…”

“…(Left) Schematic of the preparation process of the silk-polymer composite film based on flat silk cocoon; (middle) comparison of the tensile strength, modulus, and strain of the pure resin samples and composite samples; (right) mechanical properties of the pure resin and composite films under cyclic loading-unloading tests. (middle and right image) Reproduced with permission [98]. Copyright 2020, Wiley-VCH.…”