3D porous materials present a wide range of applications based on their low thermal conductivity and high specific surface area. However, most porous biomaterials have poor mechanical properties and disperse readily in water. Here, we present a facile and scalable method to prepare tough all-cellulose foams with good water stability, using electrostatic complexation between oppositely charged cellulose nanofibers (CNF). Small-angle X-ray scattering and cryogenic electron microscopy experiments showed that suspensions with oppositely charged cellulose nanofibers are a mixture of clusters and networks of entangled fibers. The balance between these structures governs the colloidal stability and the rheological behavior of CNFs in water. After the electrostatic complexation, dried foams exhibited improved modulus, and underwater stability even after vigorous agitation. This approach involves a simple and efficient protocol to prepare electrostatic complexes, which can be applied to other polysaccharides with charged groups, opening the avenue to 3D porous materials with wet resilience and improved mechanical properties.

Oppositely charged nanocelluloses: From electrostatic assemblies to 3D porous materials

ACS Spring Meeting 2021

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