Cellulose Functionalization with Methyl Ferulate in a Switchable Solvent System

A direct transesterification of cellulose with methyl ferulate was achieved in a switchable ionic liquid solvent system, a particular class of ionic liquids that can change its polarity from nonionic to ionic. Optimization of the reaction parameters was conducted, and the extent of the transesterification was monitored via FT-IR spectroscopy as well as 1H NMR spectroscopy. Subsequently, a series of cellulose esters with variable degrees of substitution (DS) were synthesized. Modifications of the derivatizing agent were also performed in order to evaluate the influence of functional groups on its reactivity, obtaining a maximum DS of 0.62. The thermal stability of the obtained cellulose ferulates was investigated, as well as their UV-absorption and antioxidant properties, revealing a free radical scavenging ability of up to 78% in 120 min. Furthermore, the recyclability of the switchable solvent system was investigated, and recycling ratios up to 91% were obtained.