Analyzing the Solubility of Cellulose in Ionic Liquids by Time-Dissolution-Concentration Superposition

Presenter: 

Crystal E. Owens

Authors: 

Crystal E. Owens, A. John Hart, Gareth H. McKinley

Author Affiliation: 

Department of Mechanical Engineering, Massachusetts Institute of Technology

Abstract: 

Textiles are a ubiquitous class of manmade material, and cellulose, which is a main ingredient of natural fibers, is the most abundant organic polymer on Earth. However, due to strong interchain hydrogen-bonding interactions, cellulose does not dissolve readily in common solvents, making it difficult to process and recycle cellulosic materials. Ionic liquids have been shown to disrupt these hydrogen bonds and thus solvate cellulose so that cellulose-based solutions can be processed like other common polymers. We monitor the dissolution of cotton-based textiles in 1-ethyl-3-methyl-imidazolium acetate [EMIM][OAc] over time using dynamic rheometry. We outline a new “time-dissolution-concentration superposition” principle, analogous to time-temperature superposition, to understand and predict the time scales and mixing strength required to dissolve and process cellulose over a range of weight concentrations (0.5 ≤ c ≤ 5%). We further characterize the extensional viscosity and relaxation time of this liquid over the same concentrations using a Capillary Breakup Extensional Rheometer (CaBER) to evaluate the spinnability of the solutions into new cellulosic fibers. Together, this information is useful to guide the processing of cellulose into new synthetic fibers, and the formation and recycling of cellulose-based materials overall.