& alpha;-Substituted ketones as reagent for Passerini modification of carboxymethyl cellulose: Toward dually functionalized derivatives and thermo-sensitive chemical hydrogels

The present works describes the Passerini modification of carboxymethyl cellulose (CMC) by using a library of nine & alpha;-substituted ketones derivatives, differing in their hydrophobicity and reactivity, conjointly with cyclohexyl isocyanide. The Passerini ligation, achieved in aqueous and mild conditions, was shown to be successful, leading to a large panel of dually functionalized CMC derivatives, in an eco-friendly manner. A particular attention was dedicated to the influence of the experimental parameters such as the stoichiometry, the nature of a co-solvent or the temperature, which allowed to tune the extent of modification. The reactivity of the ketone was proven to be governed by its i) compatibility with water, ii) sterical accessibility, and by iii) the presence of neighboring electron-withdrawing group. The resulting Passerini CMC products modified by methacrylate moieties (CMC-MA) were used as reactive macromonomer under a grafting through approach. The copolymerization of CMC-MA with oligoethylene glycol methacrylate (OEGMA) and diethylene glycol methacrylate (DEGMA) upon thermal radical reaction conditions enabled to generate tightly cross-linked chemical hydrogels, with a thermo-sensitive and thermo-reversible behavior, reflected by a macroscopical shrinkage/swelling response, and confirmed by SAXS analysis. Such chemical strategy paves the way toward multifunctional polysaccharide-based networks with potential utilizations as drug delivery devices, dye removals or actuators.

Automated summary

This work presents a Passerini modification of carboxymethyl cellulose (CMC) using a library of nine α-substituted ketone derivatives and cyclohexyl isocyanide. The Passerini ligation, carried out in aqueous and mild conditions, successfully produces eco-friendly dually functionalized CMC derivatives. The study investigates various experimental parameters, such as stoichiometry, co-solvent nature, and temperature, to control the extent of modification. The resulting Passerini CMC products are further modified with methacrylate moieties and used for grafting through copolymerization, leading to thermoresponsive hydrogels with potential applications in drug delivery, dye removal, and actuation.