Initial investigations funded by the Solid State and Materials Chemistry(SSMC) Program have indicated that the creation of supramolecular liquid crystalline networks produce materials with very interesting properties - simple one-ringed pyridyl systems produce networks that tie the reduction of liquid crystallinity in with statistical correlations of hydrogen bond acceptors. Similarly, more rigid groups allow for higher concentrations of disruptor inclusion. Non-macromolecular systems, created from simple 4-alkoxybenzoic acid groups retain liquid crystallinity at disruptor loadings above 99%. Continuation of funding from SSMC will allow for the development of new systems of varying functionality of the disrupting hydrogen bond acceptor groups (bis, tris and tetrakis), increasing rigidity and size of the hydrogen bond acceptor components (one ring pyridyl groups or longer, stilbazole structures). The study will include introduction of flexibility into all hydrogen bond accepting systems: ethyleneglycoxy chains for distonic, mesogen-forming acceptors (three, four and five) and alkyl chains (2, 4, 6 and 11 carbons) for increasing flexible netpoint creation. These systems will be studied using spectroscopic, thermal and x-ray analytical techniques. Special attention will be paid to the compositions of systems that only just eliminate liquid crystallinity, as these will be used as a probe for mesophase stability. The creation of these new liquid crystalline systems will provide valuable insight into the ability of a mesophase to stabilize in unfavorable, constrained (networked) conditions, providing insight into the nature of the formation of a mesophase, and a comparison of the quantity and strength of supramolecular forces involved in the formation of liquid crystals. The results from this work will have a broad impact on the field of supramolecular liquid crystals. The applications of hydrogen bonded mesogens are limited by the fragility of the associative chain structure. Imparting new characteristics to supramolecular liquid crystalline systems would provide new materials, combining the stabilities of covalent species with the lability and healing capabilities of hydrogen bonded associative chain structures.
NON TECHNICAL SUMMARY
This supported work will study the effects of reversible bonding on liquid crystalline polymers and networks. These materials will aid in understanding the effects of non-permanent linkages on the formation of materials important to the optical display industry. New visualization devices could be designed from the results of this work. Beyond the scientific impact of this project, activities will be used to enhance research infrastructure and give undergraduate students opportunities to carry out potentially industrially significant work. Over half of the student body at the University of Wisconsin- Eau Claire is low-income (11%) or first generation (41%) and about 60% are female, all of which are underrepresented in the scientific communities. According to the American Chemical Society UW-Eau Claire was recently ranked third nationally in the number of chemistry graduates -the highest of any Wisconsin college or university. Also, almost half of all UW- Eau Claire Chemistry undergraduates matriculate into graduate or professional programs. The research activities described will greatly enhance student training and intellectual development through hands-on experience with sophisticated techniques, equipment and the opportunities to develop their work for publication in professional journals and to present their findings at international meetings to an audience of the experts in the field.
