Matching Items (2)
Filtering by
- All Subjects: Early Stress Detection
- All Subjects: Iodide-based Ionic Liquids
- All Subjects: Water-ionic Liquid Mixtures
- Creators: Nofen, Elizabeth
- Resource Type: Text
Description
Iodide-based ionic liquids have been widely employed as sources of iodide in electrolytes for applications utilizing the triiodide/iodide redox couple. While adding a low-viscosity solvent such as water to ionic liquids can greatly enhance their usefulness, mixtures of highly viscous iodide-containing ILs with water have never been studied. Thus, this paper investigates, for the first time, mixtures of water and the ionic liquid 1-butyl-3-methylimidazolium iodide ([BMIM][I]) through a combined experimental and molecular dynamics study. The density, melting point, viscosity and conductivity of these mixtures were measured experimentally. The composition region below 50% water by mole was found to be dramatically different from the region above 50% water, with trends in density and melting point differing before and after that point. Water was found to have a profound effect on viscosity and conductivity of the IL, and the effect of hydrogen bonding was discussed. Molecular dynamics simulations representing the same mixture compositions were performed. Molecular ordering was observed, as were changes in this ordering corresponding to water content. Molecular ordering was related to the experimentally measured mixture properties, providing a possible explanation for the two distinct composition regions identified by experiment.
ContributorsNgan, Miranda L (Author) / Dai, Lenore (Thesis director) / Nofen, Elizabeth (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
The ability to sense applied damage and correlate it with a measurable signal is extremely desirable in any material application to prevent catastrophic failure and the possible loss of use of the material or human injury. Mechanochemistry, in which mechanical forces induce chemical changes, can allow for targeted damage detection by way of embedded mechanophore units, with certain mechanophore chemistries emitting a fluorescent signal in response an applied force. In this work, we successfully employed microparticles of the mechanophore dimeric 9-anthracene carboxylic acid (Di-AC) in a thermoset polyurethane matrix to study their application as universal stress-sensing fillers in network polymer matrix composites. Under a compressive force, there is bond breakage in the mechanically weak cyclooctane photodimers of Di-AC, such that there is reversion to the fluorescent anthracene-type monomers. This fluorescent emission was then correlated to the applied strain, and the precursors to damage were detected with a noticeable fluorescent signal change at an applied strain of only 2%. This early damage detection was additionally possible at very low particle loadings of 2.5 and 5 wt%, with the 5 wt% loading showing enhanced material properties compared to the 2.5 wt%, due to particle reinforcement in the composite. Overall, the synthesis of Di-AC as a stress-sensitive particle filler allows for facile addition of advanced functionality to these ubiquitous thermoset composites.
ContributorsDasgupta, Avi Ryan (Author) / Dai, Lenore (Thesis director) / Nofen, Elizabeth (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05