Characterization and Control of Nanoparticle Structure and Dispersion

Phillip M. Duxbury

Department of Physics and Astronomy

Michigan State University

East Lansing, MI 48824

Characterization of atomic structure is essential to progress in design of functional nanomaterials. We have demonstrated that x-ray and/or neutron pair distribution functions may be used to carry out ab-initio determination of solid state nanostructures [1], even when crystallography fails. We use methods based on interatomic distances extracted from scattering data, instead of the Bragg peaks which are usually used in structural characterization. Using this approach it may be possible to find accurate local atomic structure for non-crystalline materials with irregularly repeated nanostructural motifs.

Dispersion of small particles in polymers is often limited due to the depletion attraction, however we have found certain regimes in which nanoparticles have a greater propensity to disperse [2]. With this understanding, we can control the entropic and enthalpic contributions to the free energy enabling control of the self-assembly of nanoparticles in thin polymer films, facilitating a variety of applications. An important next step is the design of soft nanoparticles prior to self-assembly. Molecular dynamics simulations demonstrating the feasibility of nanoparticle design using irreversible folding will be presented [3].

[1] P. Juhas, D.M. Cherba, P.M. Duxbury, W.F. Punch, S.J.L. Billinge, Nature 440, 655 (2006).

[2] M. Mackay, A. Tuteja, P.M. Duxbury, C.J. Hawker, C. Van Horn, Z. Guan, G. Chen, R.S. Krishnan, Science 311, 1740 (2006).

[3] J. W. Liu, M.E. Mackay and P.M. Duxbury, preprint (2006).