0804197_Lodge

1. Unusual Phase Behavior of PEO/PEG in Ionic LiquidsTimothy P. Lodge, University of Minnesota-Twin Cities, DMR 0804197 Ionic liquids (Ils) are promising ingredients in energy storage devices such as lithium ion batteries, fuel cells, and supercapacitors, because they are chemically and thermally robust, and have high ionic conductivity. However, they need to be solidified within polymer matrices, of which polyethylene oxide (PEO) is very promising. We have shown that PEO can phase separate from certain ILs upon heating, which is interestingly similar to the behavior of PEO in water. Hydrogen bonding between polymer and solvent plays a key role, as illustrated in the figure; simply changing the end groups on the polymer can shift the phase boundary by 50 degrees. More unusual is the fact that the critical composition is shifted to high polymer concentrations, an effect that we are now exploring with the Lipson group at Dartmouth. Lower critical solution temperature phase diagrams for PEO (M = 2,000) with either two hydroxy, two methoxy, or one hydroxy, one methoxy end groups in the common ionic liquid [EMIM][BF4] H.-N. Lee, N. Newell, Z. Bai, and T. P. Lodge, Macromolecules, 45, 3627-3633 (2012).http://dx.doi.org/10.1021/ma300335p

2. Polymer Day: You Make It, You Break ItTimothy P. Lodge, University of Minnesota-Twin Cities, DMR 0804197 In collaboration with colleagues Marc Hillmyer, Chris Macosko, Theresa Reineke and Frank Bates, we conduct an annual hands-on lab for high school girls. Under the heading “You Make It, You Break it”, 24 students participate in a morning of polymer synthesis (left picture) and an afternoon of testing physical properties (right). Ten graduate students from our research groups also participate in guiding the experiments. This program is part of a summer camp entitled “Exploring Careers in Engineering & Physical Science”, sponsored by the College of Science and Engineering.