Tailoring strength of nanocellulose foams by electrostatic complexation

Supramolecular assembly of biobased components in water is a promising strategy to construct advanced materials. Herein, electrostatic complexation was used to prepare wet-resilient foams with improved mechanical property. Small-angle X-ray scattering and cryo-transmission 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. Foams prepared from suspensions exhibited maximum compressive modulus at the mass composition of 1:1 (ca 0.12 MPa), suggesting that meaningful attractive interactions happen at this point and act as stiffening structure in the material. Besides the electrostatic attraction, hydrogen bonds and hydrophobic contacts may also occur within the clustering, improving the water stability of cationic foams. These results may provide a basis for the development of robust allcellulose materials prepared in water, with nontoxic chemicals.

Automated summary

The study on using electrostatic complexation to prepare wet-resilient foams in water showed that suspensions of oppositely charged cellulose nanofibers form clusters and networks of fibers, with the balance between these structures affecting colloidal stability and rheological behavior. The foams prepared from these suspensions exhibited maximum compressive modulus at a 1:1 mass composition, indicating meaningful attractive interactions and potential hydrogen bonds and hydrophobic contacts within the clustering structure. These findings may pave the way for developing robust allcellulose materials using nontoxic chemicals in water.