scholarly journals Rheology of Concentrated Polymer/Ionic Liquid Solutions: An Anomalous Plasticizing Effect and a Universality in Nonlinear Shear Rheology

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 877 ◽  
Author(s):  
Zhonghua Liu ◽  
Wei Wang ◽  
Florian J. Stadler ◽  
Zhi-Chao Yan
Keyword(s):  
Ionic Liquid ◽  
Polymer Chains ◽  
Fractional Free Volume ◽  
Segmental Dynamics ◽  
Start Up ◽  
Nonlinear Stress ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Nonlinear Shear ◽  
Complex Polymer

An anomalous plasticizing effect was observed in polymer/ionic liquid (IL) solutions by applying broad range of rheological techniques. Poly(ethylene oxide)(PEO)/IL solutions exhibit stronger dynamic temperature dependence than pure PEO, which is in conflict with the knowledge that lower-Tg solvent increases the fractional free volume. For poly(methy methacrylate)(PMMA)/IL solutions, the subtle anomaly was detected from the fact that the effective glass transition temperature Tg,eff of PMMA in IL is higher than the prediction of the self-concentration model, while in conventional polymer solutions, Tg,eff follows the original Fox equation. Observations in both solutions reveal retarded segmental dynamics, consistent with a recent simulation result (Macromolecules, 2018, 51, 5336) that polymer chains wrap the IL cations by hydrogen bonding interactions and the segmental unwrapping delays their relaxation. Start-up shear and nonlinear stress relaxation tests of polymer/IL solutions follow a universal nonlinear rheological behavior as polymer melts and solutions, indicating that the segment-cation interaction is not strong enough to influence the nonlinear chain orientation and stretch. The present work may arouse the further theoretical, experimental, and simulation interests in interpreting the effect of complex polymer-IL interaction on the dynamics of polymer/IL solutions.

Cluster–Micelle Transition of a Thermo- and Photoresponsive ABC Triblock Copolymer in an Ionic Liquid

2019 ◽  
Vol 72 (2) ◽  
pp. 155
Author(s):  
Aya Saruwatari ◽  
Kei Hashimoto ◽  
Ryota Tamate ◽  
Ryoji Usui ◽  
Hisashi Kokubo ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Transition Temperature ◽  
Ethylene Oxide ◽  
Uv Irradiation ◽  
Low Temperatures ◽  
Triblock Copolymer ◽  
Abc Triblock Copolymer ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Azobenzene Groups

We report the photocontrollable micelle–cluster transition of an ABC-type triblock copolymer in an ionic liquid (IL). Polystyrene-b-poly(ethylene oxide)-b-poly(4-phenylazobenzyl acrylamide-r-N-isopropylacrylamide) (PSt-b-PEO-b-P(AzoBnAm-r-NIPAm)) was synthesised, where PSt is IL-phobic, PEO is IL-philic, and P(AzoBnAm-r-NIPAm) is photo- and thermoresponsive in the IL. At high temperatures, the triblock copolymer forms micelles with PSt cores; furthermore, at low temperatures, micelles self-assemble into clusters induced by the aggregation of P(AzoBnAm-r-NIPAm). Under UV irradiation, the micelles form clusters at lower temperatures than that in the dark because of the change in the solubility of P(AzoBnAm-r-NIPAm) induced by photoisomerisation of the azobenzene groups, indicating that this triblock copolymer has a photocontrollable micelle–cluster transition temperature.

Effect of halides on the solvation of poly(ethylene oxide) in the ionic liquid propylammonium nitrate

2019 ◽  
Vol 534 ◽  
pp. 649-654 ◽  
Author(s):  
Ryan Stefanovic ◽  
Zhengfei Chen ◽  
Paul A. FitzGerald ◽  
Gregory G. Warr ◽  
Rob Atkin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ethylene Oxide ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Evidence of re-entrant behavior in laponite-PEO systems

2005 ◽  
Vol 899 ◽  
Author(s):  
Hossein Baghdadi ◽  
Surita R. Bhatia ◽  
Elizabeth E. C. Jensen ◽  
Nalini Easwar
Keyword(s):  
Molecular Weight ◽  
Viscosity Solution ◽  
High Viscosity ◽  
Polymer Chains ◽  
Low Viscosity ◽  
End Distance ◽  
Depletion Force ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Electrostatic Repulsions

AbstractRheology and dynamic light scattering capture re-entrant behavior of laponite-polymer systems. Neat laponite under basics conditions and concentrations of 2wt% or greater forms a viscoelastic soft glass due to electrostatic repulsions. We show that that addition of low molecular weight poly(ethylene oxide) (PEO) melts the glass due to a depletion force. The depletion force speeds up dynamics in the system resulting in a low viscosity solution. A re-entrant viscoelastic solid is formed with the addition of high molecular weight PEO due to the polymer chains bridging between laponite particles. As expected the transition from a low to high viscosity solution scales with the polymer mean square end-to-end distance and gap between laponite particles.

Sign in / Sign up

Export Citation Format

Share Document