Study on the regularity of cellulose degradation in ionic liquids

Ionic liquids (ILs) show the superiority in dissolving and spinning of cellulose. In this work, wood pulp and microcrystalline cellulose were dissolved respectively in two ILs, 1-allyl-3-methylimidazolium chloride ([Amim] Cl) and 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP), to investigate the regularity of cellulose degradation in ILs. A novelmethod for determining degree of polymerization of cellulose employed ILs was proposed and its accuracy was compared with the traditional method. The results indicated that cellulose depolymerized seriouslywith the increase of time and temperature in [Amim]Cl than in [Emim]DEP. In addition, after cellulose dissolving for 72 h, none of the reducing sugar remained in the recycled [Emim]DEP, however, more than 2% reducing sugar can be measured in the recycled [Amim]Cl. These results are consistent with FTIR investigation, i.e., [Amim]Cl shows greater dissolution capability for cellulose than [Emim]DEP. Therefore, [Emim]DEP shows great prospects in the continuous industrial spinning process under the determined temperature of 90-100 degrees C. (C) 2020 Elsevier B.V. All rights reserved.