Matching Items (3)
Filtering by
- All Subjects: Mechanophores
- Creators: Dai, Lenore
- Creators: Ngan, Miranda L
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
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
This study aims to determine the feasibility of producing mechanophore-incorporated epoxy that can be healed. This was accomplished by grafting a synthesized mechanophore into tris(2-aminoethyl)amine to create a new epoxy hardener. Then this branched hardener was combined with a second hardener, diethylenetriamine (DETA). A proper ratio of the branched hardener to the DETA will ensure that the created epoxy will retain the force responsive characteristics without a noticeable decline in both the physical and thermal properties. Furthermore, it was desired that the natural structure of the epoxy would be left in place, and there would only be enough branched hardener present to elicit a force response and provide the possibility for healing. The two hardeners would then be added to Diglycidyl Ether of Bisphenol F (DGEBPF), which is the epoxy resin. The mechanophore-incorporated epoxy was compared to a standard epoxy—just DETA and DGEBPF—and it was determined that the incorporation of the mechanophore led to an 8.2 degrees Celsius increase in glass transition temperature, and a 33.0% increase in cross link density. This justified the mechanophore-incorporated epoxy as a feasible alternative to the standard, as its primary thermal and physical properties were not only equal, but superior. Then samples of the mechanophore-incorporated epoxy were damaged with a 3% tensile strain. This would cause a cycloreversion in the central cyclobutane inside of the mechanophore. Then they were healed with UV light, which would redimerize the severed hardener moieties. The healed samples saw a 4.69% increase in cross-link density, demonstrating that healing was occurring.
ContributorsPauley, Bradley (Author) / Dai, Lenore (Thesis director) / Gunckel, Ryan (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
The problem of catastrophic damage purveys in any material application, and minimizing its occurrence is paramount for general health and safety. We have successfully synthesized, characterized, and applied dimeric 9-anthracene carboxylic acid (Di-AC)-based mechanophores particles to form stress sensing epoxy matrix composites. As Di-AC had never been previously applied as a mechanophore and thermosets are rarely studied in mechanochemistry, this created an alternative avenue for study in the field. Under an applied stress, the cyclooctane-rings in the Di-AC particles reverted back to their fluorescent anthracene form, which linearly enhanced the overall fluorescence of the composite in response to the applied strain. The fluorescent signal further allowed for stress sensing in the elastic region of the stress\u2014strain curve, which is considered to be a form of damage precursor detection. Overall, the incorporation of Di-AC to the epoxy matrix added much desired stress sensing and damage precursor detection capabilities with good retention of the material properties.
ContributorsWickham, Jason Alexander (Co-author) / Nofen, Elizabeth (Co-author, Committee member) / Koo, Bonsung (Co-author) / Chattopadhyay, Aditi (Co-author) / Dai, Lenore (Co-author, Thesis director) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05