Paper Number
SM40
Session
Polymers Solutions, Melts, and Blends
Title
Associating polymer features of native cellulose in ionic liquid solutions
Presentation Date and Time
October 13, 2021 (Wednesday) 4:35
Track / Room
Track 1 / Ballroom 5
Authors
- Parisi, Daniele (FORTH, IESL)
- Bostwick, Joshua (Pennsylvania State University)
- Utomo, Nyalaliska W. (Pennsylvania State University)
- Wattana, Ravisara (Pennsylvania State University)
- Nazari, Behzad (Pennsylvania State University)
- Colby, Ralph H. (The Pennsylvania State University, Material Science and Engineering)
Author and Affiliation Lines
Daniele Parisi, Joshua Bostwick, Nyalaliska W. Utomo, Ravisara Wattana, Behzad Nazari and Ralph H. Colby
Material Science and Engineering, The Pennsylvania State University, University Park, PA 16802
Speaker / Presenter
Colby, Ralph H.
Keywords
polymer solutions
Text of Abstract
Cellulose is the most abundant bio-based polymer natural resource on Earth today. Certain ionic liquids (IL) have been discovered to be the best solvents to dissolve cellulose at the molecular level. Despite the promising role that natural polymers may undertake in the near future in replacing synthetic polymers, still many challenges exist. In the past few years, we demonstrated that cellulose in ionic liquid solutions are very sensitive to humidity, with significant increase of the elastic properties with increasing water content. It has been also observed that cellulose chains adsorb at the solution/gas interface, yielding a total rheological response which is the sum of bulk and interfacial contributions, studied using a double wall ring interfacial measurement and a cone partitioned plate bulk solution measurement. Here we address the associating polymer features exhibited by native cellulose in solutions with varying IL, in both linear and nonlinear viscoelastic regimes. We observed three aspects attributed to associations between cellulose chains: i) For a given cellulose sample, the viscoelasticity is very different in the three ionic liquids we study. ii) The concentration (c) dependence of the terminal time (t) is much stronger (t ~ c^7) than that of neutral polymers in good solvent (t ~ c^4). iii) The shear stress growth coefficient in steady-shear flow overcomes the complex viscosity, violating the empirical Cox-Merz relationship. We attribute the unusual positive divergence to chain-chain associations promoted by the shear flow, occurring when chains are significantly stretched in the flow direction. The effect of various IL on the association properties was investigated as well.