Tough and Transparent Supramolecular Cross-Linked Co-Assembled Silk Fibroin Films for Passive Radiative Cooling

Silk fibroin (SF) is a natural biomaterial from silk, which has outstanding biocompatibility. However, regeneration SF materials usually suffer from brittleness, which restricts their applications. Here, a novel supramolecular co-assembly strategy is reported for the preparation of a Bolas-shaped polyethylene glycol peptide (BPP)/SF film, where the peptide and SF form a robust payload co-assembled network and polyethylene glycol (PEG) fragments form supramolecular cross-linking in this network. The obtained BPP/SF film shows both high stress (27.8 MPa), high toughness (3.64 MJ m⁻³), high transparency (89%), and high mid-infrared (MIR) emissivity (90.5%). In passive radiative cooling, the BPP/SF film results in a 2.7 °C reduction in the temperature of the human arm skin and a 14.6 °C reduction in the temperature of the solar cell. More importantly, this novel BPP co-assembly SF material can be recycled and reused while maintaining its original mechanical strength. This work provides a novel strategy for fabricating regenerative SF materials with ultra-strong and ultra-tough mechanical performance.