Carboxymethyl Cellulose Nanofibrils with a Treelike Matrix: Preparation and Behavior of Pickering Emulsions Stabilization

Carboxymethyl cellulose nanofibrils (CMCNFs) are of great importance in the fields of sustainable chemistry and energy materials but challenging in preparation, e.g., low yield, pollution, and morphology control. In this work, CMCNFs with a quantitative yield (95%) and good morphology control were successfully achieved using a simple, low-cost, and relatively ecofriendly protocol. Water-insoluble carboxymethyl cellulose (CMC) with a low degree of substitution (DS <= 0.35) was obtained via moderate alkalization and etherification of cellulose raw materials and then was mechanically fibrillated to prepare CMCNFs using a microfluidizer. As the DS of the CMCNFs was increased from 0.05 to 0.35, the diameter was obviously decreased from 100 to 35 nm without changing the treelike matrix that was confirmed by TEM characterization. More importantly, there is no obvious difference in the final performance of the CMCNFs derived from different cellulose raw materials (i.e., cotton and wood) through this approach. Additionally, compared with the commercial CNFs, high stabilization of Pickering emulsions stabilized by the CMCNFs (DS = 0.23) could be achieved because of its novel morphology with a network structure, implying that the CMCNFs could potentially serve as a biofunctional stabilizer.