Sustainable Modification of Carboxymethyl Cellulose by Passerini Three-Component Reaction and Subsequent Adsorption onto Cellulosic Substrates

Abstract

The present work describes the chemical modification of carboxymethyl cellulose (CMC), a widely diffused commercial cellulose ether, by means of the Passerini three-component reaction (P-3CR). The reaction, performed in homogeneous aqueous medium, was proven to be effective at combining the carboxyl groups of CMC with different aldehydes and isocyanides, leading to the formation of a wide library of Passerini-modified CMC derivatives, in a simple and environmentally friendly one-pot process. The derivatized CMC products were thoroughly characterized to confirm the modification and determine the degrees of substitution (DS). The impact of experimental parameters (i.e., reaction T, time and pH, amount of employed reagents) and structure of the reactants (different aldehydes and isocyanides) on the reaction outcome was also discussed to explore the potential of this original approach for polysaccharide modification. Finally, the adsorption ability of selected CMC samples onto a model cellulosic surface was characterized by means of quartz crystal microbalance with energy dissipation monitoring (QCM-D). The analysis confirmed the successful adsorption of the Passerini-modified CMC derivatives and highlighted a positive effect of the derivatization on the amount of adsorbed polymer. Not only does the developed strategy appear as a mild and sustainable route for CMC functionalization, but also the promising adsorption ability of the functionalized derivatives opens the path toward the straightforward modification of surface properties of cellulosic substrates.