(360d) Design of New Liquid Crystal-Based Systems with Improved Chemo-Responsiveness Towards the Detection of Nerve Gases

Authors: 
Szilvási, T., University of Wisconsin-Madison
Bao, N., University of Wisconsin-Madison
Abbott, N. L., University of Wisconsin-Madison
Mavrikakis, M., University of Wisconsin-Madison
Surface anchored nematic liquid crystals can respond to external chemical stimuli by changing their bulk orientation.1 This orientation change is the foundation for detecting chemical analytes by measuring the orientational response of the liquid crystal. Several analytes have already been identified that can be detected by liquid crystals but organophosphates, especially dimethyl-methylphosphonate (DMMP), a simulant of sarin nerve gas, has become the most important test subject.2,3 One of the most important efforts in this area is to increase the chemo-responsiveness of liquid crystal-based systems to detect analytes such as DMMP as fast as possible. We have recently developed computational models, based on quantum mechanics, to describe and predict the orientational transition of liquid crystal-based systems.4 We have also adopted a combined approach using theory and experiments together to test theoretical models against experimental results and verify predictions by synthesis and characterization.5

In this presentation, we will show improved models and simple descriptors, which can predict anchoring behavior and orientational transition of nematic liquid crystals in good agreement with experimental results. Exploiting the simple descriptors we have executed a high throughput screening to find liquid crystal-based systems with improved chemo-responsiveness. We show that the modeled parameters of the liquid crystal-based systems are strongly correlated with each other. Therefore it is difficult to predict new and better systems based on limited number of experiments and wide-range, extensive screening is needed for that which can only be realized efficiently using theory. We have evaluated several surprising, non-intuitive theoretical predictions, which were subsequently verified by experiments. We present liquid crystal-based systems with even an order of magnitude better chemo-responsiveness than current state-of-the-art systems. These results prove that the close integration between theory and experiments is a very promising path for expediting the design of new liquid crystal-based chemo-responsive systems.

1. Shah, R. R.; Abbott, N. L., Science, 2001, 293, 1296.
2. Hunter, J.T.; Abbott, N.L., Applied Materials and Interfaces, 2013, 6, 2362
3. Yang, K. L.; Cadwell, K.; Abbott, N. L., Journal of Physical Chemistry B, 2004, 108, 20180.

4. Roling L. T.; Scaranto, J.; Herron, J. A.; Yu, H.; Choi, S.; Abbott, N. L.; Mavrikakis, M., Nature Communication, 2016, 7, 13338.

5. Szilvási, T.; Roling, L. T.; Yu, H.; Rai, P.; Choi, S.; Twieg, R. J.; Mavrikakis, M.; Abbott, N. L., Chemistry of Materials, 2017, accepted.