LAUSR

Interactions between polymer chains and nanoparticles can play a dominant role in composites mechanics, yet the control of such interfacial dynamics is still a significant challenge. This paper reports the effect of pH on cellulose nanofibrils (CNFs) transient hydrogels network mechanics via interfacial ionic cross-linking bonds. For this purpose, carboxylated CNFs are incorporated with amine groups terminated 8-arm poly(ethylene glycol) (PEG-NH2) to assemble the first noncovalent network via reversible ionic interactions at the CNF surfaces, where the end-group acrylate modified linear difunctional PEG forms the second lightly covalent cross-linked network. The viscoelastic properties of the supramolecular gels are examined as a function of pH, and the unique transient mechanics resulting from CNF-PEG complexation structures show that the processing from acidic-to-alkaline pH change leads to the gel cross-links transition from covalent type to covalent–noncovalent hybrid one. This finding offers an alternative way to tune CNF gels mechanical reinforcement and sheds light on the pH dependence of network architectural changes.