Facile Exfoliation of Silk Nanofibrils Enabled by Hydrogen Bond Network Reconfiguration in Deep Eutectic...

Silk nanofibers (SNFs) with distinctive physicochemical properties are promising nanoscale building blocks of porous materials, yet high-yield exfoliation using green solvents remains challenging. Herein, hydrogen-bonding small molecules (water, methanol, and ethanol) were introduced into deep eutectic solvents (DESs) to reconfigure hydrogen-bond networks and promote exfoliation. Among them, DES/water mixtures proved most effective: adding 30 wt % water reduced average SNF diameter from 239 ± 184 nm to 109 ± 27 nm and delivered a yield of 98.3% within 24 h. The improvement is attributed to hydrogen-bond reorganization, decreased viscosity, and enhanced proton transfer. The resulting SNFs preserved silk's hierarchical structures and were assembled into flexible membranes with a tensile strength of 34 MPa. These porous membranes effectively removed microplastics, with rejection rates above 91% through combined size exclusion and adsorption. This work demonstrates DES/water mixtures as sustainable solvent systems for scalable SNF production and the fabrication of high-performance membranes for water purification.