Tuning Chain Relaxation from an Amorphous Biopolymer Film to Crystals by Removing Air/Water Interface Limitations

Abstract A promising route to the synthesis of protein‐mimetic materials that are capable of strong mechanics and complex functions is provided by intermolecular β‐sheet stacking. An understanding of the assembly mechanism on β‐sheet stacking at molecular‐level and the related influencing factors determine the potential to design polymorphs of such biomaterials towards broad applications. Herein, we quantitatively reveal the air/water interface (AWI) parameters regulating the transformation from crowding amorphous aggregates to ordered phase and show that the polymorph diversity of β‐sheet stacking is regulated by the chain relaxation‐crystallization mechanism. An amorphous macroscale amyloid‐like nanofilm is formed at the AWI, in which unfolded protein chains are aligned in a short‐range manner to form randomly packed β‐sheets. The subsequent biopolymer chain relaxation‐crystallization to form nanocrystals is further triggered by removing the limitations of energy and space at the AWI.