The influence of ionic liquid concentration on microcrystalline cellulose modification

Abstract

Ethanolic ionic liquid (IL) solutions, containing different 1-n-butyl-3-methylimidazolium chloride (C4MImCl) concentrations were used to modify the surface of commercial microcrystalline cellulose (MCC). The chosen ratios were: 4, 8, 16, and 32 wt.% of IL, in relation to the MCC mass. These treatments with IL did not affect the MCC morphology. FTIR analysis showed the characteristic bands of C4MImCl when the IL concentration was higher than 4 wt.%. XRD diffractograms show that the crystals may have been disrupted for IL concentrations above 4 wt.%. 1H NMR confirmed the formation of strong hydrogen bonds between C4MImCl and MCC, especially for MCC treated with 4 wt.% of IL. The functionalization using IL, regardless of the content, showed two DTG peaks, without altering the MCC Arrhenius’ parameters and degradation mechanisms. 4 wt.% of C4MImCl proved to be suitable for the MCC surface modification, improving thermal stability without detrimental effects on MCC morphology.