Interfacial Materialization Enabled by Cellulose Nanofibril Surfactants

Biphasic liquid systems, serving as platforms with spatially directing functionality, achieve the integration of bio-mass nano-building blocks into advanced materials. Using liquid-liquid interfaces, a series of assemblies based on cellulose nanocrystals (CNCs) emerges, yet with limited application prospects, as the assemblies are mechanically fragile and thus incapable of withstanding processing-induced stresses. Here, we propose flexible cellulose nanofibrils (CNFs) as alternative assembling blocks and exploit their interfacial assembly to construct functional materials. Through an interfacial co-assembly strategy, CNFs spontaneously adsorb, assemble, and entangle at the water-toluene interface, forming reinforced yet elastic interfacial multi-layers. These assemblies are robust enough to yield multi-dimensional constructs, such as 3D porous foams and 1D biocompatible filaments, with recyclable oil-water separation and promising bioengineering applications.