Templated freezing assembly precisely regulates molecular assembly for free-standing centimeter-scale microtextured nanofilms

Nature provides diverse models for manufacturing complex and hierarchical materials by controlling molecular assembly at scales ranging from sub-nano to macroscale. However, developing artificial strategies for manufacturing hierarchical materials with comparable machining capabilities to nature is extremely challenging. Here, a templated freezing assembly strategy is reported, enabling simultaneously regulating molecular assembly spatiotemporally to obtain hierarchical materials with structure control from sub-nano to macroscale. In this way, unique centimeter-scale freestanding nanofilms are assembled from diverse molecules, e.g., proteins and conjugated polymers. A generated silk fibroin (SF) nanofilm presents a tunable beta-sheet fraction from 5% to 47%, fiber width from 30 to 3,000 nm, and micro-textures with desired shapes. Such a strategy will lay the foundation for customizing hierarchical functional materials from single or multi-component molecules, e.g., desired bio-scaffolds with controlled cell adhesion.