Determining Factors of Interparticle Spacing in 2-d Arrays of Covalently-Crosslinked, Thiol-Capped Gold Nanoparticle Films

Brianna Check, Muriel Metko, Zachary Walbrun, and Dr. Jennifer A. Dahl, Department of Chemistry, University of Wisconsin - Eau Claire, 105 Garfield Ave, Eau Claire, WI 54701

Alkanethiol-capped gold nanoparticles with variable ligand shell thicknesses were compressed into 2-d arrays using a Langmuir trough, and covalently crosslinked using various solutions of dithiols to yield flexible films of nanoparticles. The nanoparticles were prepared via the Brust route and differed only in the length (L) of the alkyl chain of the thiol. Nanoparticle 2-d arrays were transferred to a substrate by Langmuir-Blodgett deposition and imaged using Transmission Electron Microscopy to analyze interparticle spacing. It was found that for films of nanoparticles with softer, liquid-like native ligand shells, the interparticle spacing in the finished array was dictated by the length of the incoming crosslinking agent.  Conversely, nanoparticles with rigid, semi-crystalline native ligand shells maintained predictable interparticle spacing of 2L, in accord with the thickness of the ligand shell. Crosslinking attempts with 1,6-hexanedithiol were deemed unsuccessful, as the molecule was too small to effectively function as a crosslinker. Dithiols of intermediate lengths proved to be the most effective at forming crosslinked arrays. Surprisingly, the largest molecule utilized, 1,6-hexane bis(11-mercaptoundecanoate), did not effectively function as a crosslinker. To better understand the relative effectiveness of the crosslinking molecules, computational modeling of the molecules in solution was performed using Gaussian View and the Blugold Supercomputing Cluster. These efforts revealed that 1,6-hexane bis(11-mercaptoundecanoate) maintains a semi-cyclic structure in chloroform solution, inhibiting its capacity to perform the crosslinking reaction, while the most effective crosslinkers maintained a nearly linear conformation in solution. This study highlights the importance of utilizing computational modeling to inform the design and reaction dynamics of nanoscale composite materials.

Additional Abstract Information

Presenter: Brianna Check

Institution: University of Wisconsin - Eau Claire

Type: Poster

Subject: Chemistry

Status: Approved

Time and Location

Session: Poster 4
Date/Time: Tue 11:00am-12:00pm
Session Number: 3621