The influence of ionic liquid concentration on microcrystalline cellulose modification
Eduardo Fischer Kerche, Roberta Motta Neves, Heitor Luiz Ornaghi, Ademir J. Zattera, Henri Stephan Schrekker
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.