469888 Theoretical and Experimental Investigation of Microphase Separation in Mixed Thiol Monolayers on Silver Nanoparticles

Wednesday, November 16, 2016: 3:33 PM
Golden Gate 7 (Hilton San Francisco Union Square)
Steven Merz1, Zachary Farrell1, Sergei A. Egorov2 and David Green1, (1)Chemical Engineering, University of Virginia, Charlottesville, VA, (2)Department of Chemistry, University of Virginia, Charlotteville, VA

Controlling spatial patterning in nanoparticle monolayers is key to tuning nanoparticle interfacial properties. One method of inducing phase separation in nanoparticle monolayers is using ligands with chain length differences in the monolayer. This chain length mismatch is thought to create an entropic driving force for phase separation into stripy monolayers which maximize free volume for the longer ligand. Our work focuses on quantifying this effect using a combination of experimental and computational techniques. To do this we look at phase separation in alkanethiol monolayers on silver nanoparticles. The monolayers consist of two different alkanethiol ligands, one long ligand, dodecanethiol, and a shorter alkanethiol ligand, undecanethiol to butanethiol. In our work we use a MALDI-TOF technique, developed in a previous paper[1], which quantifies degree of phase separation in the nanoparticle monolayer experimentally. Additionally, we run Self-Consistent Field Theory (SCFT) and Monte Carlo atomistic simulations for each alkanethiol pairing to determine the exact spatial patterning that we expect to see with each system. We then calculate a predicted MALDI-MS spectrum from each simulation using a technique established in our previous paper[1]. This allows us to directly compare the experimental and computational results both quantitatively and qualitatively. With this comparison we get greater assurance that the simulation results accurately reflect the experimental system.

References

[1] Farrell, Z.; Merz, S.; Seager, J.; Dunn, C.; Egorov, S.; Green, D. L. Angew. Chemie Int. Ed. 2015, 54, 6479–6482.


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