Ionic liquid (IL), [BMIM]Cl-water was applied in cellulose pretreatment process and the pretreated cellulose was used in subsequent polyethylene glycol liquefaction process as a new application method. Cellulose recovery rate and molecular weight value of pretreated cellulose were investigated to understand the influence of IL-water mixtures by adding the different amount of catalysis on cellulose crystalline structure. Gel permeation chromatograph, X-ray diffraction, Fourier transform infrared spectrometer and thermo gravimetric/differential thermal analysis were used to clarify the changes of pretreated cellulose. The results showed that the pretreated cellulose was improved in crystalline structure, molecular weight distribution and thermal stability. The liquefied residues from untreated cellulose and pretreated cellulose were considered as a significant index to determine the effect of IL-water mixture on cellulose. It suggested that the lower molecular weight of cellulose was obtained, the crystalline structure was disrupted and less order was formed. The liquefied residues result suggested that the lower residues at the latter stages of the reaction from the pretreated cellulose were observed.
 H. Pan, “Synthesis of Polymers from Organic Solvent Liquefied Biomass: A Review,” Renewable & Sustainable Energy Reviews, Vol. 15, No. 7, 2011, pp. 3454-3463. http://dx.doi.org/10.1016/j.rser.2011.05.002
 Y. Kurimoto, M. Takeda, S. Doi, Y. Tamura and H. Ono, “Network Structures and Thermal Properties of Polyurethane Films Prepared from Liquefied Wood,” Bioresource Technology, Vol. 77, No. 1, 2001, pp. 33-40.
 H. Wang and H. Z. Chen, “A Novel Method of Utilizing the Biomass Resource: Rapid Liquefaction of Wheat Straw and Preparation of Biodegradable Polyurethane Foam (PUF),” Journal of the Chinese Institute of Chemical Engineers, Vol. 38, No. 2, 2007, pp. 95-102.
 M. Niu, G. Zhao and M. H. Alma, “Polycondensation Reaction and Its Mechanism during Lignocellulosic Liquefaction by an Acid Catalyst,” Forestry Studies in China, Vol. 13, No. 1, 2011, pp. 71-79.
 J. Yip, M. Chen, Y. S. Szeto and S. Yan, “Comparative Study of Liquefaction Process and Liquefied Products from Bamboo Using Different Organic Solvents,” Bioresource Technology, Vol. 100, No. 12, 2009, pp. 6674-6678. http://dx.doi.org/10.1016/j.biortech.2009.07.045
 M. Kobayashi, T. Asano, M. Kajiyama and B. Tomita, “Effect of Ozone Treatment of Wood on Its Liquefaction,” Journal of Wood Science, Vol. 51, No. 4, 2005, pp. 348-356. http://dx.doi.org/10.1007/s10086-004-0664-9
 S. H. Lee, T. V. Doherty, R. J. Linhardt and J. S. Dordick, “Ionic Liquid-Mediated Selective Extraction of Lignin from Wood Leading to Enhanced Enzymatic Cellulose Hydrolysis,” Biotechnology and Bioengineering, Vol. 102, No. 5, 2009, pp. 1368-1376.
 S. H. Ha, N. L. Mai, G. An and Y. M. Koo, “Microwave-Assisted Pretreatment of Cellulose in Ionic Liquid for Accelerated Enzymatic Hydrolysis,” Bioresource Technology, Vol. 102, No. 2, 2011, pp. 1214-1219.
 M. Mazza, D. A. Catana, C. Vaca-Garcia and C. Cecutti, “Influence of Water on the Dissolution of Cellulose in Selected Ionic Liquids,” Cellulose, Vol. 16, No. 2, 2009, pp. 207-215.
 Z. Y. Zhang, I. M. O’Haraab and W. O. S. Doherty, “Effects of pH on Pretreatment of Sugarcane Bagasse Using Aqueous Imidazolium Ionic Liquids,” Green Chemistry, Vol. 15, 2013, pp. 431-438.
 R. P. Swatloski, S. K. Spear, J. D. Holbery and R. D. Rogers, “Dissolution of Cellulose with Ionic Liquids,” Journal of the American Chemical Society, Vol. 124, No. 18, 2002, pp. 4974-4975.
 A. A. Dwiatmoko, J. W. Choi, D. J. Suh, Y. W. Suh and H. H. Kung, “Understanding the Role of Halogen-Containing Ionic Liquids in the Hydrolysis of Cellobiose Catalyzed by Acid Resins,” Applied Catalysis A: General, Vol. 387, No. 1-2, 2010, pp. 209-214.
 M. M. Zhang, S. C.Wu, W. Zhou and B. Q. Xu, “Imaging and Measuring Single-Molecule Interaction between a Carbohydrate-Binding Module and Natural Plant Cell Wall Cellulose,” Journal of Physical Chemistry B, Vol. 116, No. 33, 2012, pp. 10049-10054.
 J. J. Cael, K. H. Gardner, J. L. Koenig and J. Blackwell, “Infrared and Raman Spectroscopy of Carbohydrates. Paper V. Normal Coordinate Analysis of Cellulose I,” Journal of the Chemical Society, Vol. 62, 1975, pp. 1145-1153. http://dx.doi.org/10.1063/1.430558
 X. Colom and F. Carrillo, “Crystallinity Changes in Lyocell and Viscose-Type Fibres by Caustic Treatment,” European Polymer Journal, Vol. 38, No. 11, 2002, pp. 2225-2230.
 M. Kacuráková, A. C. Smith, M. J. Gidley and R. H. Wilson, “Molecular Interactions in Bacterial Cellulose Composites Studied by 1D FT-IR and Dynamic 2D FT-IR Spectroscopy,” Carbohydrate Research, Vol. 337, No. 12, 2002, pp. 1145-1153.
 D. Ruan, L. Zhang, Y. Mao, M. Zheng and X. Li, “Microporous Membranes Prepared from Cellulose in NaOH/ Thiourea Aqueous Solution,” Journal of Membrane Science, Vol. 241, No. 2, 2004, pp. 265-274.
 K. Das, D. Ray, N. R. Bandyopadhyay and S. Sengupta, “Study of the Properties of Microcrystalline Cellulose Particles from Different Renewable Resources by XRD, FTIR, Nanoindentation, TGA and SEM,” Journal of Polymers and the Environment, Vol. 18, No. 4, 2010, pp. 532-538. http://dx.doi.org/10.1007/s10924-010-0167-2
 M. Poletto, V. Pistor, M. Zeni and A. J. Zattera, “Crystalline Properties and Decomposition Kinetics of Cellulose Fibers in Wood Pulp Obtained by Two Pulping Processes,” Polymer Degradation and Stability, Vol. 96, 2010, pp. 679-685.
 Y. C. Zhang, A. Ikeda, N. Hori, A. Takemura, H. Ono and T. Tamada, “Characterization of Liquefied Product from Cellulose with Phenol in the Presence of Sulfuric Acid,” Bioresource Technology, Vol. 97, No. 2, 2006, pp. 313-321. http://dx.doi.org/10.1016/j.biortech.2005.02.019