Chemical Engineering Journal 147 (2009) 13–21 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Room temperature ionic liquids (RTILs): A new and versatile platform for cellulose processing and derivatization Yan Cao a , Jin Wu b , Jun Zhang b,∗ , Huiquan Li a,∗∗ , Yi Zhang a , Jiasong He b a Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China b Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Engineering Plastics (KLEP), Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China article info Keywords: Cellulose Room temperature ionic liquids (RTILs) Dissolution Regeneration Derivatization abstract Recent studies on the application of room temperature ionic liquids (RTILs) in cellulose chemistry have made great progresses. This has been providing a new and versatile platform for the wide utilization of cellulose resources and creation of novel functional materials. In this paper, the research progress in the field of dissolution, regeneration and derivatization of cellulose with RTILs are reviewed. And the perspective of RTIL application in cellulose industry is also discussed. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Cellulose is the most common organic polymer on the Earth, with an estimated annual natural production of 1.5 × 10 12 tons, and is considered as an almost inexhaustible source of raw materials [1]. Hence, effective utilization of cellulose not only reduces the consumption of our limited fossil resources but also protects the environment of the Earth. Starting with dissolving pulp as a puri- fied raw material, cellulose is converted by large-scale industrial processing into regenerated materials (fibers, films, food casings, membranes, sponges, and among others) and cellulose derivatives (ethers and esters). However, processing and derivatization of cellu- lose are difficult in general, because this natural polymer is neither meltable nor soluble in conventional solvents due to its hydro- gen bonded and partially crystalline structure. Therefore, present industrial production of regenerated cellulose and cellulose deriva- tives are in long time dominated by polluting viscose process and heterogeneous processes, respectively [2]. With increasing govern- mental regulations in industries, the need to implement “green” processes for cellulose processing and to explore alternative routes for the functionalization of cellulose with simpler reagents and less steps is getting increasingly important. Abbreviations: AdmimBr, 1-N-allyl-2,3-dimethylimidazolium bromide; AmimCl, 1-N-allyl-3-methylimidazolium chloride; BmimCl, 1-N-butyl-3-methylimidazolium chloride; BmimBr, 1-N-butyl-3-methylimidazolium bromide; BmimSCN, 1-N-butyl- 3-methylimidazolium sulfocyanate; BmimAc, 1-N-Butyl-3-methylimidazolium acetate; BdmimCl, 1-N-butyl-2,3-dimethylimidazolium chloride; EmimAc, 1- N-ethyl-3-methylimidazolium acetate; EmimCl, 1-N-ethyl-3-methylimidazolium chloride. ∗ Corresponding author. Tel.: +86 1062 621355; fax: +86 1062 561822. ∗∗ Corresponding author. E-mail addresses: jzhang@iccas.ac.cn (J. Zhang), hqli@home.ipe.ac.cn (H. Li). Over the past decades, several solvent systems have been devel- oped for manufacturing regenerated cellulose materials and cellu- lose derivatives. Typical examples of these solvents include lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc), LiCl/N-methyl-2- pyrrolidine (NMP), LiCl/1,3-dimethyl-2-imidazolidinone (DMI), dimethyl sulfoxide (DMSO)/tetrabuthlammonium fluoride trihy- drate (TBAF), DMSO/paraformaldehyde, N-methyl-morpholine-N- oxide (NMMO), aqueous solutions of NaOH, some molten salt hydrates, such as LiClO 4 ·3H 2 O, and LiSCN·2H 2 O, and some aque- ous solutions of metal complexes [3]. However, the above solvent systems are limited to their dissolving capability, toxicity, high cost, solvents recovery, uncontrollable side reaction, and instability dur- ing cellulose processing and/or derivatization. Current interests in room temperature ionic liquids (RTILs) stem primarily from the heightened awareness of their potential appli- cations in “Green Chemistry” and the associated emphasis on clean manufacturing processes. Due to their unique properties such as chemical and thermal stability, non-flammability and immeasur- able low vapor pressure, RTILs seem to be an attractive alternative to conventional volatile organic solvents. RTILs show promises for a variety of applications in chemical industry including chemical synthesis, catalysis, separation, and preparation of materials. There- fore, RTILs have attracted considerable attentions from both the academic and industrial communities in recent years [4]. Since Swatloski et al. [5] reported the dissolution of cellulose in alkyl substituted imidazolium RTILs, it has attracted consider- able attention in this area [6,7]. Recent studies on the application of RTILs in cellulose chemistry have made great progresses. Some new advances in this field include dissolution of cellulose in some new RTILs, the mechanism of cellulose dissolution in RTILs, prepa- ration of some new functional cellulose materials by using RTIL, syntheses of more kinds of cellulose derivatives in RTILs, regener- ated cellulose fibers with outstanding mechanical properties spun 1385-8947/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.cej.2008.11.011