NIRT: Nanometer Stoichiometric Particle Compound Solutions and Control of their Self-Assembly into the Condensed Phase

Chris Sorensen, C. Aakeröy, A. Chakrabarti, K. Klabunde and B. LawDepartments of Physics and Chemistry, Kansas State University

Goals

•Synthesize a library of monodisperse functional nanoparticles (NP).•Study NP solution phase behavior and nucleation.•Controlled assembly of NP into 2d and 3d superlattices and gels.•Study NP solution surface and interfacial properties.

1. Synthesis

NPs of Au, Ag, CdSe, In. Dia. ~ 4 to 10nmLigands. Nonfunctionalized: CnSH, CnNH2, P(C8)3

Functionalized: HSCnCOOH, HSCnOH, HSCn polyols

Solvents: toluene, t-butyltoluene, 2-butanone, CH3OH, water, DMSO.

Solvated Metal Atom Dispersion Reactor

bis(8-imidazol-1-yloctyl)disulfide

2. Solution Phase and Nucleation

Fat Fractals

Solution of Au/SHC11COOH in DMSO yields fractal/superlattice hybrid, with hydrogen bonds when quenched.

Au/C12SH NP (5.5nm) colloidal solution at different temperatures, solvent: t-butyltoluene + 2-butanone.

The phase transition is reversible!

Static and dynamic light scattering to observe cluster formation via nucleation as quench NP solution from one phase to two.

One phase; individual,dissolved 5.5nm NPs.

Two phase; clusters of NPs.

Deep quench yields lots of small clusters, shallow quench a few big clusters.

3. NP-NP Interactions

4. Surface Interactions

• Core-core• Core-ligand• Ligand-ligand

All mediated by the solvent

Droplets of Au/3-mercapto-1, 2-propanediol NP in H2O on glass. Left no NP, contact angle = 7o; right with NP, contact angle = 23o.

x = 1.3 is found in Au/C12SH NP superlattices.

NPs affect wetting.