Fibers and Polymers 2012, Vol.13, No.3, 289-294 289 Influence of Residual Ionic Liquid on the Thermal Stability and Electromechanical Behavior of Cellulose Regenerated from 1-Ethyl-3-Methylimidazolium Acetate Suresha K. Mahadeva and Jaehwan Kim* Creative Research Center for EAPap Actuator, Department of Mechanical Engineering, Inha University, Incheon 402-751, Korea (Received June 20, 2011; Revised September 29, 2011; Accepted September 20, 2011) Abstract: The regenerated cellulose films were prepared by dissolving cotton cellulose pulp directly in room temperature ionic liquid namely, 1-ethyl-3-methylimidazolium acetate at 80 o C, followed by washing/curing in different coagulants namely, methanol, deionized water, methanol- deionized water, and isopropyl alcohol- deionized water. It was found that the type of coagulants employed for curing the cellulose films has a significant influence on the amount of residual ionic liquid entrapped in the films. The amount of residual ionic liquids was 2.68, 1.01, 0.84, and 0.75 wt.% for the films cured with deionized water, isopropyl alcohol- deionized water, methanol, and methanol- deionized water, respectively. The DTG peaks of regenerated cellulose films showed two decomposition temperatures at 280 o C and 320 o C. Among all the cases studied, deionized water curing case showed the lowest decomposition temperature, attributed to entrapment of large residual ionic liquid in it. Electromechanical characteristic of the regenerated cellulose films was also investigated. Keywords: Cellulose, 1-Ethyl-3-Methylimidazolium Acetate, Thermal stability, Regeneration, Curing Introduction Cellulose is one of the most naturally abundant biopolymers. Due to its biocompatible and biodegradable characteristics, cellulose finds wide range of applications from textile to immobilization of proteins, antibodies and pharmaceuticals [1]. Recently, cellulose has been re-discovered as a smart material, which undergoes mechanical deformation under the action of electric filed and is termed as electroactive paper (EAPap). This material has advantages in terms of biocompatibility, easy modification, eco-friendly and low price [2,3]. Cellulose EAPap is made by dissolving cellulose fibers, forming film, followed by electrode deposition on both sides of it. In order to utilize this newly developed material as biomimetic actuators, sensors, micro-electro- mechanical devices, electronic display and so forth, it is necessary to remove the solvents from the cellulose EAPap completely. Since 1970s, many solvent systems have been investigated for cellulose dissolution and regeneration which includes, lithium chloride/N,N-dimethylacetamide (LiCl/DMAc), LiCl/ N-methylpyrrolidine, LiCl/1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide (DMSO)/paraformaldehyde, N-methyl- morpholine-N-oxide, sodium hydroxide/urea, and aqueous solutions of metal complexes [4-9]. Each of these solvent systems has their own pros and cons. Ionic liquids (ILs) have been spotlighted and considered as green solvents with many combinations that provide an unprecedented diversity. They also have been used as reaction solvents, extraction solvents, and electrolyte materials due to their negligibly small vapor pressure, high thermal stability, and high ionic conductivity. Recently, ILs have been reported as a solvent for dissolution and regeneration of cellulose due to their ability to break the hydrogen bonds. Also it is reported that these solvents can be recovered upon dissolution and regeneration of cellulose, yielding high quality regenerated cellulose film [10-12]. In this context, the present investigation aims to study the influence of entrapped residual ionic liquid in the cellulose matrix on its thermal stability and electromechanical behavior upon their regeneration from 1-ethyl-3-methylimidazolium acetate. We processed regenerated cellulose films contained different amount of entrapped ionic liquid, by dissolving cotton cellulose pulp in 1-ethyl-3-methylimidazolium acetate (EMIMAc) and regenerated by washing them in different coagulants namely; methanol (MeOH), deionized water (DW), MeOH/DW (30:70), and isopropyl alcohol (IPA)/ DW. Consequences of the entrapped residual EMIMAc on the thermal stability and electromechanical behavior of the regenerated cellulose films were investigated by employing a field effect scanning electron microscope (FESEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractogram (XRD), thermogravimmetric analysis (TGA) and electro- mechanical behavior. Experimental Materials Cotton cellulose (MVE, DPW 4580) was purchased from Buckeye Technologies Co., USA. 1-Ethyl-3-methylimidazolium acetate (EMIMAc) with 98 % (w/w) purity was purchased from C-Tri, Korea. Methanol (98 %) and isopropyl alcohol (IPA, 98 %) were purchased from Sigma Aldrich, USA. All the chemicals were used without further purification. *Corresponding author: jaehwan@inha.ac.kr DOI 10.1007/s12221-012-0289-3